| 1. |
- Abelius, Martina, 1980-
(författare)
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Immunological interactions between mother and child during pregnancy in relation to the development of allergic diseases in the offspring
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background: Pregnancy and allergic disease have both been postulated as T-helper 2 (Th2) phenomena. Thus, the increased propensity of allergic mothers to mount Th2-responses might generate favourable effects on the maintenance of pregnancy, but might also be unfavorable, as fetal exposure to a strong Th2 environment could influence the immune development in the offspring to a Th2-like phenotype, favouring IgE production and possibly allergy development later in life. The influence of the intrauterine environment on the immunity and allergy development in the offspring needs to be further investigated.Aim: The aim of this thesis was to explore the Th1/Th2 balance in allergic and non-allergic women during pregnancy and its influence on the shaping of the Th1/Th2 profile in the neonate and the development of allergic diseases in the offspring.Material and methods: The study group included 20 women with and 36 women without allergic symptoms followed during pregnancy (gestational week 10-12, 15-16, 25, 35, 39) and 2 and 12 months postpartum, and their children followed from birth to 6 years of age. The circulating Th1-like chemokines CXCL9, CXCL10, CXCL11, Th2-like chemokines CCL17, CCL18 and CCL22, and the allergen-induced secretion of interleukin-4 (IL-4), IL-5, IL-10, IL-13, Interferon-γ (IFN-γ), CXCL10 and CCL17 were measured by Luminex and ELISA. The allergen-specific and total IgE levels were quantified using ImmunoCAP Technology. mRNA expression of Th1-, Th2-, Treg- and Th17-associated genes were measured by PCR arrays and real-time PCR.Results: We found that sensitised women with allergic symptoms had increased total IgE levels and birch- and cat-induced IL-5, IL-13 and CCL17 responses during pregnancy as compared with postpartum. The non-sensitised women without allergic symptoms had elevated cat-induced IL-5 and IL-13 responses and lower birch- and cat-induced IFN-γ during pregnancy, but similar IgE levels as compared with postpartum.Maternal total IgE levels during and after pregnancy correlated with cord blood (CB) IgE and CCL22 levels (regardless of maternal allergy status). Circulating CXCL11, CCL18 and CCL22 levels during pregnancy and postpartum correlated with the corresponding chemokine levels in the offspring at various time points during childhood. Maternal IL-5 expression in peripheral blood mononuclear cells (PBMC) was associated with neonatal Galectin-1, and placental p35 expression was negatively associated with neonatal Tbx21 expression. Increased mRNA expression of CCL22 in cord blood mononuclear cells (CBMC), and increased CCL17 and CCL22 levels in CB were observed in children later developing allergic symptoms and sensitisation as compared with children who did not. Development of allergic symptoms and sensitisation were associated with increased total IgE, CCL17, CCL18 and CCL22 levels during childhood.Conclusions: Maternal allergy was associated with a pronounced Th2 deviation during pregnancy, shown as increased total IgE levels and birch- and cat-induced IL-5, IL-13 and CCL17 responses during pregnancy, possibly exposing their fetuses to a particular strong Th2 environment during gestation.Correlations were shown between the maternal immunity during pregnancy and the offspring’s immunity at birth and later during childhood, indicating an interplay between the maternal and fetal immunity.Allergy development during the first 6 years of life was associated with a marked Th2 deviation at birth and a delayed down-regulation of this Th2-skewed immunity during childhood.
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| 2. |
- Alkadarou, Tayseer, et al.
(författare)
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Immunological characteristics of hyperreactive malarial splenomegaly syndrome in sudanese patients
- 2013
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Ingår i: Journal of Tropical Medicine. - : Hindawi Limited. - 1687-9686 .- 1687-9694. ; 2013, s. 961051-
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Tidskriftsartikel (refereegranskat)abstract
- Hyperreactive Malarial Splenomegaly (HMS) is defined as a massive enlargement of the spleen resulting from abnormal immune responses after repeated exposure to the malaria parasites. This study was carried out in Khartoum, Sudan. Sudan is considered to be one of the countries where HMS is quite prevalent. The objective of the study was to determine the incidence of HMS in patients who reported to the Omdurman Tropical Diseases Hospital (OMTDH) in Sudan and to investigate the basic laboratory and immunological characteristics of this condition in these patients. A cross-sectional study was carried out in OMTDH, and all patients with enlarged spleens were included in the study. Thirty-one out of 335 (9.3%) patients were diagnosed as having the HMS condition using international criteria for HMS diagnosis. The mean serum immunoglobulin M (IgM) levels in HMS patient groups were 14.3 ± 5 g/L, and this was significantly higher compared with geographically matched controls (P < 0.001). Immunoglobulin G (IgG) C anticircumsporozoite (CSP) antibody levels were higher in the HMS patients although the difference was not statistically significant, when compared with a group of patients with mild malaria. In comparison with naïve European controls, both the HMS and the mild malaria groups had significantly higher antimalarial antibody levels P < 0.001 and P < 0.01, respectively. Plasma levels of interleukin 10 (IL10) and interferon gamma (IFN γ ) were significantly increased in the HMS patients compared with the healthy control donors (P < 0.05 and P < 0.01) for IL10 and IFN γ , respectively. The findings of this study suggest that HMS is one of the significant causes of tropical splenomegaly in Sudan. HMS is associated with significant elevations of circulating IgM and antimalarial IgG antibodies as well as IL10 and IFN γ .
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| 3. |
- Amoako-Sakyi, Daniel, et al.
(författare)
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A STAT6 Intronic Single-Nucleotide Polymorphism is Associated with Clinical Malaria in Ghanaian Children
- 2016
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Ingår i: Genetics and Epigenetics. - 1179-237X. ; 8, s. 7-14
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Tidskriftsartikel (refereegranskat)abstract
- Malaria pathogenesis may be influenced by IgE responses and cytokine cross-regulation. Several mutations in the IL-4/STAT6 signaling pathway can alter cytokine cross-regulation and IgE responses during a Plasmodium falciparum malarial infection. This study investigated the relationship between a STAT6 intronic single-nucleotide polymorphism (rs3024974), total IgE, cytokines, and malaria severity in 238 Ghanaian children aged between 0.5 and 13 years. Total IgE and cytokine levels were measured by ELISA, while genotyping was done by polymerase chain reaction-restriction fragment length polymorphism (RFLP). Compared with healthy controls, heterozygosity protected against clinical malaria: uncomplicated malaria (odds ratios [OR] = 0.13, P < 0.001), severe malarial anemia (OR = 0.18, P, 0.001), and cerebral malaria (OR = 0.39, P = 0.022). Levels of total IgE significantly differed among malaria phenotypes (P = 0.044) and rs3024974 genotypes (P = 0.037). Neither cytokine levels nor IL-6/IL-10 ratios were associated with malaria phenotypes or rs3024974 genotypes. This study suggests a role for rs3024974 in malaria pathogenesis and offers further insights into an IL-4/STAT6 pathway mutation in malaria pathogenesis.
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| 4. |
- Amodu, O. K., et al.
(författare)
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Association of the sickle cell trait and the ABO blood group with clinical severity of malaria in southwest Nigeria
- 2012
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Ingår i: Acta Tropica. - : Elsevier BV. - 0001-706X .- 1873-6254. ; 123:2, s. 72-77
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Tidskriftsartikel (refereegranskat)abstract
- In regions of high Plasmodium falciparum malaria endemicity, certain erythrocyte polymorphisms confer resistance to severe disease. In this study, we evaluate the role of the sickle cell trait (HbS) and ABO blood groups in the clinical manifestations of childhood malaria in Southwest Nigeria. The subjects comprised 3100 children (53% males, median age 39 months), including 1400 children with uncomplicated malaria, 1000 children with asymptomatic malaria and 700 with severe malaria. Haemoglobin (Hb) types were determined using electrophoresis and serum agglutination techniques were used to determine ABO blood groups. Blood group O was the commonest ABO blood group (47.7%) in the study population, the others were A (22.5%), B (25.2%) and AB (4.6%). The frequencies of the HbAS and HbAC were 14.4% and 5.8%, respectively. In regression models adjusting for age, gender, parasite density and blood group, HbAS was associated with a reduced risk of severe malaria OR=0.46 (CI95%: 0.273-0.773). Among severe malaria subjects, HbAS was associated with significantly lower parasite densities. The protective effect of blood group 0 was demonstrated with a decreased risk of severe malaria OR=0.743 (CI95%: 0.566-0.976) after adjusting for age, gender and parasite density and Hb genotype. Blood group B was associated with increased risk of severe malaria OR=1.638 (CI95%: 1.128-2.380) after adjusting for age, gender, packed cell volume, parasite density and Hb genotype. We have confirmed from this large study of Nigerian children the major protective effective of the sickle cell heterozygous state against both cerebral malaria and severe malarial anaemia. We also show that the B blood group is associated with an increased risk of severe malaria. In conclusion, the sickle cell haemoglobin type and ABO groups modulate the risk of severe malaria in Nigerian children.
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| 5. |
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| 6. |
- Anchang-Kimbi, Judith K., et al.
(författare)
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Antenatal care visit attendance, intermittent preventive treatment during pregnancy (IPTp) and malaria parasitaemia at delivery
- 2014
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Ingår i: Malaria Journal. - : Springer Science and Business Media LLC. - 1475-2875. ; 13, s. 162-
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Tidskriftsartikel (refereegranskat)abstract
- Background: The determinants and barriers for delivery and uptake of IPTp vary with different regions in sub-Saharan Africa. This study evaluated the determinants of ANC clinic attendance and IPTp-SP uptake among parturient women from Mount Cameroon Area and hypothesized that time of first ANC clinic attendance could influence uptake of IPTp-SP/dosage and consequently malaria parasite infection status at delivery. Methods: Two cross sectional surveys were carried out at the Government Medical Centre in the Mutengene Health Area, Mt Cameroon Area from March to October 2007 and June 2008 to April 2009. Consented parturient women were consecutively enrolled in both surveys. In 2007, socio-demographic data, ANC clinic attendance, gestational age, fever history and reported use/dosage of IPTp-SP were documented using a structured questionnaire. In the second survey only IPT-SP usage/dosage was recorded. Malaria parasitaemia at delivery was determined by blood smear microscopy and placental histology. Results and discussion: In 2007, among the 287 women interviewed, 2.2%, 59.7%, and 38.1% enrolled in the first, second and third trimester respectively. About 90% of women received at least one dose SP but only 53% received the two doses in 2007 and by 2009 IPTp-two doses coverage increased to 64%. Early clinic attendance was associated (P = 0.016) with fever history while being unmarried (OR = 2.2; 95% CI: 1.3-3.8) was significantly associated with fewer clinic visits (<4visits). Women who received one SP dose (OR = 3.7; 95% CI: 2.0-6.8) were more likely not to have attended >= 4visits. A higher proportion (P < 0.001) of women with first visit during the third trimester received only one dose, meanwhile, those who had an early first ANC attendance were more likely (OR = 0.4; 95% CI = 0.2 - 0.7) to receive two or more doses. Microscopic parasitaemia at delivery was frequent (P = 0.007) among women who enrolled in the third trimester and had received only one SP dose than in those with two doses. Conclusion: In the study area, late first ANC clinic enrolment and fewer clinic visits may prevent the uptake of two SP doses and education on early and regular ANC clinic visits can increase IPTp coverage.
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| 7. |
- Anchang-Kimbi, Judith K, et al.
(författare)
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Diagnostic comparison of malaria infection in peripheral blood, placental blood and placental biopsies in Cameroonian parturient women.
- 2009
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Ingår i: Malaria Journal. - : Springer Science and Business Media LLC. - 1475-2875. ; 8, s. 126-
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: In sub-Saharan Africa, Plasmodium falciparum malaria in pregnancy presents an enormous diagnostic challenge. The epidemiological and clinical relevance of the different types of malaria diagnosis as well as risk factors associated with malaria infection at delivery were investigated. METHOD: In a cross-sectional survey, 306 women reporting for delivery in the Mutenegene maternity clinic, Fako division, South West province, Cameroon were screened for P. falciparum in peripheral blood, placental blood and placental tissue sections by microscopy. Information relating to the use of intermittent preventive treatment in pregnancy with sulphadoxine/pyrimethamine, history of fever attack, infant birth weights and maternal anaemia were recorded. RESULTS: Among these women, P. falciparum infection was detected in 5.6%, 25.5% and 60.5% of the cases in peripheral blood, placental blood and placental histological sections respectively. Placental histology was more sensitive (97.4%) than placental blood film (41.5%) and peripheral blood (8.0%) microscopy. In multivariate analysis, age (< or = 20 years old) (OR = 4.61, 95% CI = 1.47 - 14.70), history of fever attack (OR = 2.98, 95% CI = 1.58 - 5.73) were significant risk factors associated with microscopically detected parasitaemia. The use of > or = 2 SP doses (OR = 0.18, 95% CI = 0.06 - 0.52) was associated with a significant reduction in the prevalence of microscopic parasitaemia at delivery. Age (>20 years) (OR = 0.34, 95% CI = 0.15 - 0.75) was the only significant risk factor associated with parasitaemia diagnosed by histology only in univariate analysis. Microscopic parasitaemia (OR = 2.74, 95% CI = 1.33-5.62) was a significant risk factor for maternal anaemia at delivery, but neither infection detected by histology only, nor past infection were associated with increased risk of anaemia. CONCLUSION: Placenta histological examination was the most sensitive indicator of malaria infection at delivery. Microscopically detected parasitaemia was associated with increased risk of maternal anaemia at delivery, but not low-grade parasitaemia detected by placental histology only.
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| 8. |
- Anchang-Kimbi, Judith K., et al.
(författare)
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IgG isotypic antibodies to crude Plasmodium falciparum blood-stage antigen associated with placental malaria infection in parturient Cameroonian women
- 2016
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Ingår i: African Health Sciences. - : African Journals Online (AJOL). - 1680-6905 .- 1729-0503. ; 16:4, s. 1007-1017
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Tidskriftsartikel (refereegranskat)abstract
- Background: Few studies have reported an association between placental malaria (PM) infection and levels of isotypic antibodies against non-pregnancy associated antigens. Objective: To determine and evaluate IgG isotypic antibody levels to crude P. falciparum blood stage in women with and without PM infection. Methods: Levels of IgG (IgG1-IgG4) and IgM to crude P. falciparum blood stage antigen were measured by ELISA in 271 parturient women. Placental malaria infection was determined by placental blood microscopy and placental histology. Age, parity and intermittent preventive treatment during pregnancy with sulphadoxine-pyrimethamine (IPTp-SP) usage were considered during analysis. Results: P. falciparum-specific IgG1 (96.5%) and IgG3 (96.7%) antibodies were predominant compared with IgG2 (64.6%) and IgG4 (49.1%). Active PM infection was associated with significant increased levels of IgG1, IgG4 and IgM while lower levels of these antibodies were associated with uptake of two or more IPTp-SP doses. PM infection was the only independent factor associated with IgG4 levels. Mean IgG1 + IgG3/IgG2 + IgG4 and IgG1 + IgG2 + IgG3/IgG4 ratios were higher among the PM-uninfected group while IgG4/IgG2 ratio prevailed in the infected group. Conclusion: PM infection and IPTp-SP dosage influenced P. falciparum-specific isotypic antibody responses to blood stage antigens. An increase in IgG4 levels in response to PM infection is of particular interest.
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| 9. |
- Arama, Charles, et al.
(författare)
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A recombinant Bacille Calmette-Guerin construct expressing the Plasmodium falciparum circumsporozoite protein enhances dendritic cell activation and primes for circumsporozoite-specific memory cells in BALB/c mice
- 2012
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Ingår i: Vaccine. - : Elsevier. - 0264-410X .- 1873-2518. ; 30:37, s. 5578-5584
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Tidskriftsartikel (refereegranskat)abstract
- A protective malaria vaccine may induce both high levels of neutralising antibodies and strong T-cell responses. The Plasmodium falciparum circumsporozoite protein (CSp) is a leading pre-erythrocytic vaccine candidate. CSp is a week immunogen per se, but Mycobacterium bovis Bacille Calmette-Guérin (BCG) has excellent adjuvant activity and has been utilized as a vector to deliver heterologous vaccine candidate antigens. It is safe in immunocompetent individuals and inexpensive to produce. We assessed in vitro and in vivo a recombinant BCG-expressing CSp (BCG-CS) as malaria vaccine candidate. Immunisation of BALB/c mice with BCG-CS augmented numbers of dendritic cells (DCs) in draining lymph nodes and in the spleen. The activation markers MHC-class-II, CD40, CD80 and CD86 on DCs were significantly upregulated by BCG-CS as compared to wild-type BCG (wt-BCG). In vitro stimulation of bone marrow-derived DCs and macrophages with BCG-CS induced IL-12 and TNF-α production. BCG-CS induced higher phagocytic activity in macrophages as compared to wt-BCG. Immunogenicity studies show that BCG-CS induced CS-specific antibodies and IFN-γ-producing memory cells. In conclusion, BCG-CS is highly efficient in activating antigen-presenting cells (APCs) for priming of adaptive immunity. Implications for the rational design of novel vaccines against malaria and TB, the two major devastating poverty-related diseases, are discussed.
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| 10. |
- Arama, Charles, et al.
(författare)
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Epigenetics and Malaria Susceptibility/Protection : A Missing Piece of the Puzzle
- 2018
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Ingår i: Frontiers in Immunology. - : Frontiers Media SA. - 1664-3224. ; 9
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Forskningsöversikt (refereegranskat)abstract
- A better understanding of stable changes in regulation of gene expression that result from epigenetic events is of great relevance in the development of strategies to prevent and treat infectious diseases. Histone modification and DNA methylation are key epigenetic mechanisms that can be regarded as marks, which ensure an accurate transmission of the chromatin states and gene expression profiles over generations of cells. There is an increasing list of these modifications, and the complexity of their action is just beginning to be understood. It is clear that the epigenetic landscape plays a fundamental role in most biological processes that involve the manipulation and expression of DNA. Although the molecular mechanism of gene regulation is relatively well understood, the hierarchical order of events and dependencies that lead to protection against infection remain largely unknown. In this review, we propose that host epigenetics is an essential, though relatively under studied, factor in the protection or susceptibility to malaria.
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| 11. |
- Arama, Charles, et al.
(författare)
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Ethnic differences in susceptibility to malaria : What have we learned from immuno-epidemiological studies in West Africa?
- 2015
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Ingår i: Acta Tropica. - : Elsevier BV. - 0001-706X .- 1873-6254. ; 146, s. 152-156
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Forskningsöversikt (refereegranskat)abstract
- There are many fundamental aspects of the immunobiology of Plasmodium falciparum infections that are not fully understood, therefore limiting our comprehension of how people become immune to malaria and why some ethnic groups living in malaria endemic areas are less susceptible than others. The complexity of parasite-host interactions and the genetic diversity of the parasites as well as the human host complicate our strategy to address this issue. In this mini-review we discuss and summarize what we have learned about African ethnic differences in susceptibility to malaria from immuno-epidemiological studies. Additionally, we suggest research topics that might be of great value for dissecting the mechanisms of protection by providing new insights into molecular interactions between the parasite and the host.
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| 12. |
- Arama, Charles, et al.
(författare)
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Genetic Resistance to Malaria Is Associated With Greater Enhancement of Immunoglobulin (Ig)M Than IgG Responses to a Broad Array of Plasmodium falciparum Antigens
- 2015
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Ingår i: Open forum infectious diseases. - : Oxford University Press (OUP). - 2328-8957. ; 2:3
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Tidskriftsartikel (refereegranskat)abstract
- Background. People of the Fulani ethnic group are more resistant to malaria compared with genetically distinct ethnic groups, such as the Dogon people, in West Africa, and studies suggest that this resistance is mediated by enhanced antibody responses to Plasmodium falciparum antigens. However, prior studies measured antibody responses to < 0.1% of P falciparum proteins, so whether the Fulani mount an enhanced and broadly reactive immunoglobulin (Ig) M and IgG response to P falciparum remains unknown. In general, little is known about the extent to which host genetics influence the overall antigen specificity of IgM and IgG responses to natural infections. Methods. In a cross-sectional study in Mali, we collected plasma from asymptomatic, age-matched Fulani (n = 24) and Dogon (n = 22) adults with or without concurrent P falciparum infection. We probed plasma against a protein microarray containing 1087 P falciparum antigens and compared IgM and IgG profiles by ethnicity. Results. We found that the breadth and magnitude of P falciparum-specific IgM and IgG responses were significantly higher in the malaria-resistant Fulani versus the malaria-susceptible Dogon, and, unexpectedly, P falciparum-specific IgM responses more strongly distinguished the 2 ethnic groups. Conclusions. These findings point to an underappreciated role for IgM in protection from malaria, and they suggest that host genetics may influence the antigen specificity of IgM and IgG responses to infection.
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| 13. |
- Arama, Charles, et al.
(författare)
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Heterologous prime-boost regimen adenovector 35-circumsporozoite protein vaccine/recombinant Bacillus Calmette-Guerin expressing the Plasmodium falciparum circumsporozoite induces enhanced long-term memory immunity in BALB/c mice
- 2012
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Ingår i: Vaccine. - : Elsevier BV. - 0264-410X .- 1873-2518. ; 30:27, s. 4040-4045
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Tidskriftsartikel (refereegranskat)abstract
- Background: Sustained antibody levels are a hallmark of immunity against many pathogens, and induction of long-term durable antibody titers is an essential feature of effective vaccines. Heterologous prime-boost approaches with vectors are optimal strategies to improve a broad and prolonged immunogenicity of malaria vaccines. Results: In this study, we demonstrate that the heterologous prime-boost regimen Ad35-CS/BCG-CS induces stronger immune responses by enhancing type 1 cellular producing-cells with high levels of CSp-specific IFN-gamma and cytophilic IgG2a antibodies as compared to a homologous BCG-CS and a heterologous BCG-CS/CSp prime-boost regimen. Moreover, the heterologous prime-boost regimen elicits the highest level of LLPC-mediated immune responses. Conclusion: The increased IFN-gamma-producing cell responses induced by the combination of Ad35-CS/BCG-CS and sustained type 1 antibody profile together with high levels of LLPCs may be essential for the development of long-term protective immunity against liver-stage parasites.
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| 14. |
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| 15. |
- Arama, Charles, 1975-, et al.
(författare)
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Interethnic Differences in Antigen-Presenting Cell Activation and TLR Responses in Malian Children during Plasmodium falciparum Malaria
- 2011
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 6:3, s. e18319-
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Tidskriftsartikel (refereegranskat)abstract
- The Fulani ethnic group from West Africa is relatively better protected against Plasmodium falciparum malaria as compared to other sympatric ethnic groups, such as the Dogon. However, the mechanisms behind this lower susceptibility to malaria are largely unknown, particularly those concerning innate immunity. Antigen-presenting cells (APCs), and in particular dendritic cells (DCs) are important components of the innate and adaptive immune systems. Therefore, in this study we investigated whether APCs obtained from Fulani and Dogon children exhibited differences in terms of activation status and toll-like receptor (TLR) responses during malaria infection. Lower frequency and increased activation was observed in circulating plasmacytoid DCs and BDCA-3+ myeloid DCs of infected Fulani as compared to their uninfected counterparts. Conversely, a higher frequency and reduced activation was observed in the same DC subsets obtained from peripheral blood of P. falciparum-infected Dogon children as compared to their uninfected peers. Moreover, infected individuals of both ethnic groups exhibited higher percentages of both classical and inflammatory monocytes that were less activated as compared to their non-infected counterparts. In line with APC impairment during malaria infection, TLR4, TLR7 and TLR9 responses were strongly inhibited by P. falciparum infection in Dogon children, while no such TLR inhibition was observed in the Fulani children. Strikingly, the TLR-induced IFN-γ release was completely abolished in the Dogon undergoing infection while no difference was seen within infected and non-infected Fulani. Thus, P. falciparum infection is associated with altered activation status of important APC subsets and strongly inhibited TLR responses in peripheral blood of Dogon children. In contrast, P. falciparum induces DC activation and does not affect the innate response to specific TLR ligands in Fulani children. These findings suggest that DCs and TLR signalling may be of importance for the protective immunity against malaria observed in the Fulani.
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| 16. |
- Arama, Charles, 1975-
(författare)
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Novel immunization strategies and interethnic differences in response to malaria infection
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A better understanding of the role of antigen-presenting cells (APCs) in host resistance to malaria is essential to unravel the complex interactions between the host and the parasite. This would improve the design of malaria vaccines. Mycobacterium bovis Bacillus Calmette-Guérin (BCG) has been utilized as a vector to deliver vaccine candidate antigens. We assessed the immunogenicity of a recombinant BCG-expressing (BCG-CS) circumsporozoite protein (CSp) as a malaria vaccine candidate. Immunization of BALB/c mice with BCG-CS augmented the numbers of dendritic cells (DCs) in draining lymph nodes and in the spleen. The activation markers MHC-class-II, CD40, CD80, and CD86 on DCs were significantly upregulated by BCG-CS as compared to wild-type BCG (wt-BCG). In vitro stimulation of bone marrow-derived DCs and macrophages with BCG-CS induced IL-12 and TNF-α production. BCG-CS induced higher phagocytic activity in macrophages as compared to wt-BCG. Finally, BCG-CS induced CSp-specific antibodies and IFN-γ-producing memory cells. Taken together, we found that BCG-CS is highly efficient in activating innate immune responses and could effectively prime the adaptive immune system. Heterologous prime–boost approaches using vectors are optimal strategies to improve a broad and prolonged immunogenicity of malaria vaccines. We have demonstrated in BALB/c mice that priming with a replication-defective human adenovirus serotype 35 (Ad35) vector encoding CSp (Ad35-CS), followed by boosting with BCG-CS, maintained antibody responses and significantly increased levels of long-lived plasma cells (LLPC) and IFN-g-producing cells in response to CSp peptides. The increased number of IFN-g-producing cells induced by the combination of Ad35-CS/BCG-CS and the sustained type 1 antibody profile, together with high levels of LLPCs, may be essential for the development of long-term protective immunity against liver-stage parasites. Fulani and Dogon, two sympatric ethnic groups living in northeastern Mali, are characterized by a marked difference in the susceptibility to P. falciparum malaria. We investigated whether APCs obtained from Fulani and Dogon children exhibited differences in terms of activation status and toll-like receptor (TLR) responses during malaria infection. We observed decreased activation of APCs and markedly suppressed TLR responses in Dogon children as compared to Fulani. These findings suggest that APCs and TLR signaling may be of importance for the protective immunity against malaria observed in the Fulani. In conclusion, this thesis provides new insights that could facilitate a rational design of novel vaccines against malaria. Furthermore, the results elicit some immunological bases of the APC activation underlying the differences in host susceptibility to malaria infections.
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| 17. |
- Arama, Charles, et al.
(författare)
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The path of malaria vaccine development : challenges and perspectives
- 2014
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Ingår i: Journal of Internal Medicine. - : Wiley. - 0954-6820 .- 1365-2796. ; 275:5, s. 456-466
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Forskningsöversikt (refereegranskat)abstract
- Malaria is a life-threatening disease caused by parasites of the Plasmodium genus. In many parts of the world, the parasites have developed resistance to a number of antimalarial agents. Key interventions to control malaria include prompt and effective treatment with artemisinin-based combination therapies, use of insecticidal nets by individuals at risk and active research into malaria vaccines. Protection against malaria through vaccination was demonstrated more than 30years ago when individuals were vaccinated via repeated bites by Plasmodium falciparum-infected and irradiated but still metabolically active mosquitoes. However, vaccination with high doses of irradiated sporozoites injected into humans has long been considered impractical. Yet, following recent success using whole-organism vaccines, the approach has received renewed interest; it was recently reported that repeated injections of irradiated sporozoites increased protection in 80 vaccinated individuals. Other approaches include subunit malaria vaccines, such as the current leading candidate RTS,S (consisting of fusion between a portion of the P.falciparum-derived circumsporozoite protein and the hepatitis B surface antigen), which has been demonstrated to induce reasonably good protection. Although results have been encouraging, the level of protection is generally considered to be too low to achieve eradication of malaria. There is great interest in developing new and better formulations and stable delivery systems to improve immunogenicity. In this review, we will discuss recent strategies to develop efficient malaria vaccines.
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| 18. |
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| 19. |
- Arkestål, Kurt, et al.
(författare)
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Impaired allergy diagnostics among parasite-infected patients caused by IgE antibodies to the carbohydrate epitope galactose-alpha 1,3-galactose
- 2011
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Ingår i: Journal of Allergy and Clinical Immunology. - : Elsevier BV. - 0091-6749 .- 1097-6825. ; 127:4, s. 1024-1028
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Tidskriftsartikel (refereegranskat)abstract
- Background: The carbohydrate epitope galactose-alpha 1,3galactose (a-Gal) is abundantly expressed on nonprimate mammalian proteins. We have recently shown that alpha-Gal is responsible for the IgE binding to cat IgA, a newly identified cat allergen (Fel d 5). Objective: We sought to investigate the diagnostic relevance of IgE antibodies to Fel d 5 and a-Gal among parasite-infected patients from central Africa without cat allergy compared with patients with cat allergy from the same region. Methods: Sera from 47 parasite-infected patients and 31 patients with cat allergy were analyzed for total IgE and IgE antibodies against cat dander extract (CDE) by using the ImmunoCAP system. Inhibition assay was performed with a-Gal on solid phase-bound CDE. The presence of IgE specific for the major cat allergen Fel d 1, Fel d 5, and alpha-Gal was analyzed by means of ELISA. Results: Among the 47 parasite-infected patients, 85% had IgE antibodies against alpha-Gal (OD; median, 0.175; range, 0.1021.466) and 66% against Fel d 5 (OD; median, 0.13; range, 0.1031.285). Twenty-four of the parasite-infected patients were sensitized to CDE, and 21 of them had IgE antibodies to Fel d 5 and a-Gal. There was no correlation between IgE levels to CDE and rFel d 1 among the parasite-infected patients but a strong correlation between CDE and Fel d 5 and alpha-Gal (P <. 001). Among the group with cat allergy, only 5 patients had IgE to alpha-Gal, and nearly 75% (n 5 23) had IgE to rFel d 1 (median, 7.07 kU(A)/L; range, 0.51-148.5 kUA/ L). In contrast, among the patients with cat allergy, there was a correlation between IgE levels to CDE and rFel d 1 (P <.05) but no correlation between CDE and Fel d 5 and alpha-Gal. Conclusion: IgE to alpha-Gal causes impaired allergy diagnostics in parasite-infected patients. Screening for IgE to rFel d 1 and other allergens without carbohydrates might identify patients with true cat sensitization/ allergy in parasite-infested areas.
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| 20. |
- Awah, Nancy, 1976-, et al.
(författare)
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Antibodies to the Plasmodium falciparum rhoptry protein RAP-2/RSP-2 in relation to anaemia in Cameroonian children
- 2011
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Ingår i: Parasite immunology (Print). - : Wiley. - 0141-9838 .- 1365-3024. ; 33:2, s. 104-115
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Tidskriftsartikel (refereegranskat)abstract
- Previous studies have implicated reactive antibodies to the low molecular weight rhoptry-associated proteins (RAP-1, RAP-2/RSP-2 and RAP-3) in erythroid cell destruction during Plasmodium falciparum infection. In this pilot study, the frequency, specificity and functional capacity of naturally acquired anti-RAP-2/RSP-2 antibodies were investigated in the sera of anaemic and nonanaemic malaria-infected Cameroonian children. All sera recognized RAP-2/RSP-2 by FACS, irrespective of the clinical status of the subjects. However, the anaemic children showed higher levels of IgG antibodies than the nonanaemic group, while both groups showed similar levels of IgM antibodies. Only few individuals had detectable levels of RAP-2/RSP-2-specific IgG1 and IgG3 subclass antibodies, while no IgG2 and IgG4 subclass antibodies were detected in these subjects. By ELISA, the anaemic group tended to show higher levels of antibodies to RAP-2/RSP-2 regarding all antibody classes tested, except for IgG4 and IgE. Unexpectedly, sera from the nonanaemic group activated complement to a greater extent than those from the anaemic group. These results need to be confirmed in extended studies but indicate that the effector functions of the RAP-2/RSP-2-reactive antibodies may be more important than their amounts. Such antibodies could play a role in both immunity and pathogenesis during P. falciparum infection.
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| 21. |
- Awah, Nancy W., et al.
(författare)
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Mechanisms of malarial anaemia : potential involvement of the Plasmodium falciparum low molecular weight rhoptry-associated proteins.
- 2009
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Ingår i: Acta Tropica. - : Elsevier BV. - 0001-706X .- 1873-6254. ; 112:3, s. 295-302
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Tidskriftsartikel (refereegranskat)abstract
- Plasmodium falciparum malaria is a major cause of morbidity and mortality throughout the tropics. Anaemia is a constant feature of the disease. Pregnant women mostly primigravidae and children below the age of 5 years are the most afflicted. Its pathogenesis is multifactorial and incompletely understood. Among several factors, the destruction of erythrocytes (RBCs) is the most frequently observed cause of severe malarial anaemia and the removal of non-parasitized RBCs (nEs) is thought to be the most important, accounting for approximately 90% of the reduction in haematocrit in acute malaria. Previous studies demonstrated that the tagging of nEs with the parasite antigen RAP-2 (rhoptry-associated protein-2; also designated RSP-2) due to either failed or aborted invasion by merozoites resulted in the destruction of these cells. In this study we further investigated the mechanisms mediating the destruction of nEs in the development of severe malarial anaemia and the possible involvement of RAP-2/RSP-2 and other members of the low molecular weight rhoptry complex (RAP-1: rhoptry-associated protein-1 and RAP-3: rhoptry-associated protein-3). Antibodies to the rhoptry-associated proteins were found to recognise the surface of nEs in a parasitaemia-dependent manner after merozoite release in P. falciparumin vitro cultures. These cells, as well as erythroblasts co-cultured with infected RBCs (IEs), could then be destroyed by either phagocytosis or lysis after complement activation. The ability of anti-rhoptry antibodies to mediate the destruction of RAP-2/RSP-2-tagged erythroblasts in the presence of effector cells was also investigated. Data obtained suggest that mouse monoclonal antibodies to the low molecular weight RAP proteins mediate the death of RAP-2/RSP-2-tagged erythroblasts on interaction with adherent monocytes. The mechanism of cell death is not yet fully known, but seems to involve primarily apoptosis. The above observations suggest that the antibody response against RAP-2/RSP-2 and other members of the complex could trigger the destruction of RAP-2/RSP-2-tagged host cells. Taken together it appears that during severe anaemia a defective bone marrow or dyserythropoiesis possibly due to erythroblast cell death, may overlap with the accelerated destruction of normal erythroid cells, either by opsonisation or complement activation further aggravating the anaemia which may become fatal. These observations could therefore have implications in the design, development and deployment of future therapeutic interventions against malaria.
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| 22. |
- Bolad, Ahmed, et al.
(författare)
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Distinct interethnic differences in IgG class/subclass and IgM antibody responses to malaria antigens but not in IgG responses to non-malarial antigens in sympatric tribes living in West Africa
- 2005
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Ingår i: Scandinavian Journal of Immunology. - : Wiley. - 0300-9475 .- 1365-3083. ; 61:4, s. 380-386
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Tidskriftsartikel (refereegranskat)abstract
- The well-established relative resistance to malaria observed in the Fulani ascompared with other sympatric tribes in West Africa has been attributed totheir higher levels of serum immunoglobulin (Ig) G antibodies to malarialantigens. In this study, we confirm and extend the previous findings by analysesof the levels of IgM, IgG and IgG subclasses of anti-malarial antibodies inasymptomatic individuals of different sympatric tribes in Burkina Faso(Fulani/Mossi) and Mali (Fulani/Dogon). The Fulani showed significantlyhigher median concentrations of anti-malarial IgG and IgM antibodies thanthe sympatric tribes at both locations. Although the overall subclass pattern ofantibodies did not differ between the tribes, with IgG1 and IgG3 as dominant,the Fulani showed consistently significantly higher levels of these subclasses ascompared with those of the non-Fulani individuals. No significant differenceswere seen in the levels of total IgG between the tribes, but the Fulani showedsignificantly higher levels of total IgM than their neighbours in both countries.While the antibody levels to some nonmalarial antigens showed the same patternof differences seen for antibody levels to malaria antigens, no significant suchdifferences were seen with antibodies to other nonmalarial antigens. In conclusion,our results show that the Fulani in two different countries show higherlevels of anti-malarial antibodies than sympatric tribes, and this appears not tobe a reflection of a general hyper-reactivity in the Fulani.
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| 23. |
- Boraschi, Diana, et al.
(författare)
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Immunity against HIV/AIDS, malaria, and tuberculosis during co-infections with neglected infectious diseases: recommendations for the European Union research priorities.
- 2008
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Ingår i: PLoS neglected tropical diseases. - : Public Library of Science (PLoS). - 1935-2735. ; 2:6
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Tidskriftsartikel (refereegranskat)abstract
- Infectious diseases remain a major health and socioeconomic problem in many low-income countries, particularly in sub-Saharan Africa. For many years, the three most devastating diseases, HIV/AIDS, malaria, and tuberculosis (TB) have received most of the world's attention. However, in rural and impoverished urban areas, a number of infectious diseases remain neglected and cause massive suffering. It has been calculated that a group of 13 neglected infectious diseases affects over one billion people, corresponding to a sixth of the world's population. These diseases include infections with different types of worms and parasites, cholera, and sleeping sickness, and can cause significant mortality and severe disabilities in low-income countries. For most of these diseases, vaccines are either not available, poorly effective, or too expensive. Moreover, these neglected diseases often occur in individuals who are also affected by HIV/AIDS, malaria, or TB, making the problem even more serious and indicating that co-infections are the rule rather than the exception in many geographical areas. To address the importance of combating co-infections, scientists from 14 different countries in Africa and Europe met in Addis Ababa, Ethiopia, on September 9-11, 2007. The message coming from these scientists is that the only possibility for winning the fight against infections in low-income countries is by studying, in the most global way possible, the complex interaction between different infections and conditions of malnourishment. The new scientific and technical tools of the post-genomic era can allow us to reach this goal. However, a concomitant effort in improving education and social conditions will be needed to make the scientific findings effective.
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| 24. |
- Boström, Stéphanie, 1985-, et al.
(författare)
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Biomarkers of Plasmodium falciparum infection during pregnancy in women living in Northeastern Tanzania
- 2012
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 7:11, s. e48763-
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Tidskriftsartikel (refereegranskat)abstract
- In pregnant women, Plasmodium falciparum infections are an important cause of maternal morbidity as well as fetal and neonatal mortality. Erythrocytes infected by these malaria-causing parasites accumulate through adhesive interactions in placental intervillous spaces, thus evading detection in peripheral blood smears. Sequestered infected erythrocytes induce inflammation, offering the possibility of detecting inflammatory mediators in peripheral blood that could act as biomarkers of placental infection. In a longitudinal, prospective study in Tanzania, we quantified a range of different cytokines, chemokines and angiogenic factors in peripheral plasma samples, taken on multiple sequential occasions during pregnancy up to and including delivery, from P. falciparum-infected women and matched uninfected controls. The results show that during healthy, uninfected pregnancies the levels of most of the panel of molecules we measured were largely unchanged except at delivery. In women with P. falciparum, however, both comparative and longitudinal assessments consistently showed that the levels of IL-10 and IP-10 increased significantly whilst that of RANTES decreased significantly, regardless of gestational age at the time the infection was detected. ROC curve analysis indicated that a combination of increased IL-10 and IP-10 levels and decreased RANTES levels might be predictive of P. falciparum infections. In conclusion, our data suggest that host biomarkers in peripheral blood may represent useful diagnostic markers of P. falciparum infection during pregnancy, but placental histology results would need to be included to verify these findings.
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| 25. |
- Boström, Stephanie, 1985-, et al.
(författare)
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Changes in the levels of cytokines, chemokines and malaria specific antibodies in response to Plasmodium falciparum infection in children living in sympatry in Mali
- 2012
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Ingår i: Malaria Journal. - : Springer Science and Business Media LLC. - 1475-2875. ; 11, s. 109-
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Tidskriftsartikel (refereegranskat)abstract
- Background: The Fulani are known to be less susceptible to Plasmodium falciparum malaria as reflected by lower parasitaemia and fewer clinical symptoms than other sympatric ethnic groups. So far most studies in these groups have been performed on adults, which is why little is known about these responses in children. This study was designed to provide more information on this gap. Methods: Circulating inflammatory factors and antibody levels in children from the Fulani and Dogon ethnic groups were measured. The inflammatory cytokines; interleukin (IL)-1beta, IL-6, IL-8, IL-10, IL-12p70, tumor necrosis factor (TNF) and the chemokines; regulated on activation normal T cell expressed and secreted (RANTES), monokine-induced by IFN-gamma (MIG), monocyte chemotactic protein (MCP)-1 and IFN-gamma-inducible protein (IP)-10 were measured by cytometric bead arrays. The levels of interferon (IFN)-alpha, IFN-gamma and malaria-specific antibodies; immunoglobulin (Ig) G, IgM and IgG subclasses (IgG1-IgG4) were measured by ELISA. Results: The results revealed that the Fulani children had higher levels of all tested cytokines compared to the Dogon, in particular IFN-gamma, a cytokine known to be involved in parasite clearance. Out of all the tested chemokines, only MCP-1 was increased in the Fulani compared to the Dogon. When dividing the children into infected and uninfected individuals, infected Dogon had significantly lower levels of RANTES compared to their uninfected peers, and significantly higher levels of MIG and IP-10 as well as MCP-1, although the latter did not reach statistical significance. In contrast, such patterns were not seen in the infected Fulani children and their chemokine levels remained unchanged upon infection compared to uninfected counterparts. Furthermore, the Fulani also had higher titres of malaria-specific IgG and IgM as well as IgG1-3 subclasses compared to the Dogon. Conclusions: Taken together, this study demonstrates, in accordance with previous work, that Fulani children mount a stronger inflammatory and antibody response against P. falciparum parasites compared to the Dogon and that these differences are evident already at an early age. The inflammatory responses in the Fulani were not influenced by an active infection which could explain why less clinical symptoms are seen in this group.
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