| 1. |
- Jahnmatz, Peter, et al.
(författare)
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Memory B-Cell Responses Against Merozoite Antigens After Acute Plasmodium falciparum Malaria, Assessed Over One Year Using a Novel Multiplexed FluoroSpot Assay
- 2021
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Ingår i: Frontiers in Immunology. - : Frontiers Media SA. - 1664-3224. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- Memory B cells (MBCs) are believed to be important for the maintenance of immunity to malaria, and these cells need to be explored in the context of different parasite antigens and their breadth and kinetics after natural infections. However, frequencies of antigen-specific MBCs are low in peripheral blood, limiting the number of antigens that can be studied, especially when small blood volumes are available. Here, we developed a multiplexed reversed B-cell FluoroSpot assay capable of simultaneously detecting MBCs specific for the four Plasmodium falciparum blood-stage antigens, MSP-1(19), MSP-2, MSP-3 and AMA-1. We used the assay to study the kinetics of the MBC response after an acute episode of malaria and up to one year following treatment in travelers returning to Sweden from sub-Saharan Africa. We show that the FluoroSpot assay can detect MBCs to all four merozoite antigens in the same well, and that the breadth and kinetics varied between individuals. We further found that individuals experiencing a primary infection could mount and maintain parasite-specific MBCs to a similar extent as previously exposed adults, already after a single infection. We conclude that the multiplexed B-cell FluoroSpot is a powerful tool for assessing antigen-specific MBC responses to several antigens simultaneously, and that the kinetics of MBC responses against merozoite surface antigens differ over the course of one year. These findings contribute to the understanding of acquisition and maintenance of immune responses to malaria.
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| 2. |
- Jahnmatz, Peter, et al.
(författare)
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Multiplex analysis of antigen-specific memory B cells in humans using reversed B-cell FluoroSpot
- 2020
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Ingår i: JIM - Journal of Immunological Methods. - : Elsevier BV. - 0022-1759 .- 1872-7905. ; 478
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Tidskriftsartikel (refereegranskat)abstract
- Analysis of B-cell specificities at the single cell level provides important information on how the B-cell compartment responds when challenged by infection or vaccination. We recently developed a reversed B-cell FluoroSpot assay and showed that it could be used to detect B cells specific for different antigens simultaneously in a mouse model. The aim of this study was to further develop the method to detect and quantify antigen-specific memory B cells (MBCs) in humans where circulating antigen-specific cells are less frequent. We show that MBCs specific for three antigens, tetanus toxoid, hepatitis B surface antigen and cytomegalovirus pp65, could be detected simultaneously in one well. In addition to enumerating antigen-specific MBCs, we also assessed the spot volume to estimate the intensity of the response in individual cells and found this to be a new and sensitive approach to study MBC responses after vaccination. This unique B-cell FluoroSpot approach provides a simple and sensitive multiplex analysis of MBCs and can be adapted to most antigens and host species.
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| 3. |
- Jahnmatz, Peter, et al.
(författare)
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Plasmodium falciparum-Specific Memory B-Cell and Antibody Responses Are Associated With Immunity in Children Living in an Endemic Area of Kenya
- 2022
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Ingår i: Frontiers in Immunology. - : Frontiers Media SA. - 1664-3224. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- Identifying the mechanism of naturally acquired immunity against Plasmodium falciparum malaria could contribute to the design of effective malaria vaccines. Using a recently developed multiplexed FluoroSpot assay, we assessed cross-sectional pre-existing memory B-cells (MBCs) and antibody responses against six well known P. falciparum antigens (MSP-119, MSP-2 (3D7), MSP-2 (FC27), MSP-3, AMA-1 and CSP) and measured their associations with previous infections and time to clinical malaria in the ensuing malaria season in Kenyan children. These children were under active weekly surveillance for malaria as part of a long-term longitudinal malaria immunology cohort study, where they are recruited from birth. After performing Cox regression analysis, we found that children with a breadth of three or more antigen-specific MBC or antibody responses at the baseline had a reduced risk for malaria in the ensuing P. falciparum transmission season. Specifically, MBC responses against AMA-1, MSP-2 (3D7) and MSP-3, as well as antibody responses to MSP-2 (3D7) and MSP-3 were prospectively associated with a reduced risk for malaria. The magnitude or breadth of MBC responses were however not correlated with the cumulative number of malaria episodes since birth. We conclude that increased breadth for merozoite antigen-specific MBC and antibody responses is associated with protection against malaria.
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| 4. |
- Kerkman, Priscilla, et al.
(författare)
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Generation of plasma cells and CD27-IgD- B cells during hantavirus infection is associated with distinct pathological findings
- 2021
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Ingår i: Clinical & Translational Immunology (CTI). - : John Wiley & Sons. - 2050-0068. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Human hantavirus infections can cause haemorrhagic fever with renal syndrome (HFRS). The pathogenic mechanisms arenot fully understood, nor if they affect the humoral immune system. The objective of this study was to investigate humoral immune responses to hantavirus infection and to correlate them to the typical features of HFRS: thrombocytopenia and transient kidney dysfunction.Methods: We performed a comprehensive characterisation of longitudinal antiviral B-cell responses of 26 hantavirus patients and combined this with paired clinical data. In addition, we measured extracellular adenosine triphosphate (ATP)and its breakdown products in circulation and performed in vitro stimulations to address its effect on B cells.Results: We found that thrombocytopenia was correlated to an elevated frequency of plasmablasts in circulation. In contrast, kidney dysfunction was indicative of an accumulation of CD27-IgD- B cells and CD27/low plasmablasts. Finally, we provide evidence that high levels of extracellular ATP and matrix metalloproteinase 8 can contribute to shedding of CD27 during human hantavirus infection.Conclusion: Our findings demonstrate that thrombocytopenia and kidneydysfunction associate with distinctly different effects on the humoral immune system. Moreover, hantavirus-infectedindividuals have significantly elevated levels of extracellular ATP incirculation.
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| 5. |
- Martinez-Murillo, Paola, et al.
(författare)
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CD138 and CD31 Double-Positive Cells Comprise the Functional Antibody-Secreting Plasma Cell Compartment in Primate Bone Marrow
- 2016
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Ingår i: Frontiers in Immunology. - Lausanne, Switzerland : Frontiers Media S.A.. - 1664-3224. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Plasma cells (PCs) are defined as terminally differentiated B cells that secrete large amounts of immunoglobulin (Ig). PCs that reside in the bone marrow (BM) are responsible for maintaining long-term antibody (Ab) responses after infection and vaccination, while PCs present in the blood are generally short-lived. In rhesus macaques, a species frequently used for the evaluation of human vaccines, B cells resemble those found in humans. However, a detailed characterization of BM-resident rhesus PC phenotype and function is lacking. Here, we examined Ig secretion of distinct rhesus CD138+ populations by B cell ELISpot analysis to couple phenotype with function. We demonstrate that the CD20low/-CD138+CD31+ BM population was highly enriched for antibody-secreting cells with IgG being the predominant isotype (60%), followed by IgA (33%) and IgM (7%). Transmission electron microscopy analysis confirmed PC enrichment in the CD20low/-CD138+CD31+ population with cells containing nuclei with "spokes of a wheel" chromatin structure and prominent rough endoplasmic reticulum. This panel also stained human BM PCs and allowed a clear distinction between BM PCs and short-lived peripheral PCs, providing an improved strategy to isolate PCs from rhesus BM for further analysis.
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| 6. |
- Phad, Ganesh E., et al.
(författare)
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Extensive dissemination and intraclonal maturation of HIV Env vaccine-induced B cell responses
- 2020
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Ingår i: Journal of Experimental Medicine. - : Rockefeller University Press. - 0022-1007 .- 1540-9538. ; 217:2
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Tidskriftsartikel (refereegranskat)abstract
- Well-ordered HIV-1 envelope glycoprotein (Env) trimers are prioritized for clinical evaluation, and there is a need for an improved understanding about how elicited B cell responses evolve following immunization. To accomplish this, we prime-boosted rhesus macaques with Glade C NFL trimers and identified 180 unique Ab lineages from similar to 1,000 single-sorted Envspecific memory B cells. We traced all lineages in high-throughput heavy chain (HC) repertoire (Rep-seq) data generated from multiple immune compartments and time points and expressed several as monoclonal Abs (mAbs). Our results revealed broad dissemination and high levels of somatic hypermutation (SHM) of most lineages, including tier 2 virus neutralizing lineages, following boosting. SHM was highest in the Ab complementarity determining regions (CDRs) but also surprisingly high in the framework regions (FRO, especially FR3. Our results demonstrate the capacity of the immune system to affinity-mature large numbers of Env-specific B cell lineages simultaneously, supporting the use of regimens consisting of repeated boosts to improve each Ab, even those belonging to less expanded lineages.
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| 7. |
- Rönnberg, Caroline, et al.
(författare)
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A longitudinal study of plasma BAFF levels in mothers and their infants in Uganda, and correlations with subsets of B cells
- 2021
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 16:1 January
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Tidskriftsartikel (refereegranskat)abstract
- Malaria is a potentially life-threatening disease with approximately half of the world’s population at risk. Young children and pregnant women are hit hardest by the disease. B cells and antibodies are part of an adaptive immune response protecting individuals continuously exposed to the parasite. An infection with Plasmodium falciparum can cause dysregulation of B cell homeostasis, while antibodies are known to be key in controlling symptoms and parasitemia. BAFF is an instrumental cytokine for the development and maintenance of B cells. Pregnancy alters the immune status and renders previously clinically immune women at risk of severe malaria, potentially due to altered B cell responses associated with changes in BAFF levels. In this prospective study, we investigated the levels of BAFF in a malaria-endemic area in mothers and their infants from birth up to 9 months. We found that BAFF-levels are significantly higher in infants than in mothers. BAFF is highest in cord blood and then drops rapidly, but remains significantly higher in infants compared to mothers even at 9 months of age. We further correlated BAFF levels to P. falciparum-specific antibody levels and B cell frequencies and found a negative correlation between BAFF and both P. falciparum-specific and total proportions of IgG+ memory B cells, as well as CD27− memory B cells, indicating that exposure to both malaria and other diseases affect the development of B-cell memory and that BAFF plays a part in this. In conclusion, we have provided new information on how natural immunity against malaria is formed.
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| 8. |
- Sundling, Christopher, et al.
(författare)
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B cell profiling in malaria reveals expansion and remodeling of CD11c+ B cell subsets
- 2019
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Ingår i: JCI Insight. - : American Society for Clinical Investigation. - 2379-3708. ; 4:9
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Tidskriftsartikel (refereegranskat)abstract
- Humoral immunity is important in limiting clinical disease in malaria, yet the longitudinal B cell response to infection remains unclear. We performed a 1-year prospective study in patients treated for acute Plasmodium fakiporum malaria for the first time or with previous exposure to the disease. Using an unbiased exploratory approach with mass cytometry, followed by targeted flow cytometry, we found that approximately 80% of mature B cells that proliferated in response to acute infection expressed CD11c. Only approximately 40% of CD11c+ B cells displayed an atypical B cell phenotype, with the remaining cells primarily made up of activated and resting memory B cells. The CD11c+ B cells expanded rapidly following infection, with previous exposure to malaria resulting in a significantly larger increase compared with individuals with primary infection. This was attributed to an expansion of switched CD11c+ B cells that was absent in primary infected individuals. The rate of contraction of the CD11c+ B cell compartment was independent of previous exposure to malaria and displayed a slow decay, with a half-life of approximately 300 days. Collectively, these results identify CD11c as a marker of B cells responding to malaria and further highlight differences in primary and secondary B cell responses during infection.
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| 9. |
- Sundling, Christopher, et al.
(författare)
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CTA1-DD adjuvant promotes strong immunity against human immunodeficiency virus type 1 envelope glycoproteins following mucosal immunization.
- 2008
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Ingår i: The Journal of general virology. - : Microbiology Society. - 0022-1317 .- 1465-2099. ; 89:Pt 12, s. 2954-64
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Tidskriftsartikel (refereegranskat)abstract
- Strategies to induce potent and broad antibody responses against the human immunodeficiency virus type 1 (HIV-1) envelope glycoproteins (Env) at both systemic and mucosal sites represent a central goal for HIV-1 vaccine development. Here, we show that the non-toxic CTA1-DD adjuvant promoted mucosal and systemic humoral and cell-mediated immune responses following intranasal (i.n.) immunizations with trimeric or monomeric forms of HIV-1 Env in mice and in non-human primates. Env-specific IgG subclasses in the serum of immunized mice reflected a balanced Th1/Th2 type of response. Strikingly, i.n. immunizations with Env and the CTA1-DD adjuvant induced substantial levels of mucosal anti-Env IgA in bronchial alveolar lavage and also detectable levels in vaginal secretions. By contrast, parenteral immunizations of Env formulated in Ribi did not stimulate mucosal IgA responses, while the two adjuvants induced a similar distribution of Env-specific IgG-subclasses in serum. A single parenteral boost with Env in Ribi adjuvant into mice previously primed i.n. with Env and CTA1-DD, augmented the serum anti-Env IgG levels to similar magnitudes as those observed after three intraperitoneal immunizations with Env in Ribi. The augmenting potency of CTA1-DD was similar to that of LTK63 or CpG oligodeoxynucleotides (ODN). However, in contrast to CpG ODN, the effect of CTA1-DD and LTK63 appeared to be independent of MyD88 and toll-like receptor signalling. This is the first demonstration that CTA1-DD augments specific immune responses also in non-human primates, suggesting that this adjuvant could be explored further as a clinically safe mucosal vaccine adjuvant for humoral and cell-mediated immunity against HIV-1 Env.
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| 10. |
- Sundling, Christopher
(författare)
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Dissection of HIV-1 Env-specific B cell responses in non-human primates
- 2010
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- It has been almost 30 years since the identification of HIV as the causative agent of AIDS. Despite considerable efforts to halt the spread of the virus, the epidemic continues in many parts of the world. The most efficient way to stop new infections is a prophylactic vaccine that blocks transmission at the viral portal of entry. To generate an efficacious vaccine, neutralizing antibodies directed against the envelope glycoproteins (Env), the only virally expressed proteins on the surface of the virion, likely need to be elicited. Early attempts to develop an HIV vaccine used soluble recombinant monomeric Env. This vaccine candidate generated high titers of Env binding antibodies in a large clinical trial; however, no protection against infection was observed. Since then attempts have been made to design Env immunogens that more closely mimic the native Env spike with the aim to improve the quality of vaccine-elicited humoral immune responses. Due to the lack of high resolution three dimensional structures of Env in its native conformation, these design efforts are still empirical. To guide future immunogen design efforts, it is important to understand what current Env vaccine candidates elicit in relevant pre-clinical models, both at the serological and cellular level. The focus of this thesis has been to investigate B cell responses in non-human primates following immunization with soluble HIV-1 Env trimers. We show that Env immunization in adjuvant elicits high levels of binding antibodies as well as robust peripheral memory B cell and plasma cell populations. The kinetics and magnitude of the responses at early time points after immunization are similar to those elicited by the successful human influenza and rabies vaccines. Despite these potent responses, we only observed a modest protective effect upon mucosal SHIV challenge of vaccinated animals. When quantifying the levels of Env-specific antibodies in the mucosa we found them to be 1000-10 000 fold lower than in serum, which may explain the lack of protection in this heterologous challenge model. From in vitro studies it has been proposed that interactions between Env and CD4-expressing T cells may detrimentally affect T cell function. To investigate if in vivo interactions between Env immunogens and CD4-expressing cells would negatively affect the elicitation of Envspecific immune responses, CD4 binding-competent and CD4 binding-defective trimers were constructed and inoculated into non-human primates. No difference was observed between the groups in regards to Env-specific antibody titers, memory B cell or T cell levels and functionality, indicating that Env binding to CD4 in vivo was not detrimental to vaccine elicited responses. Furthermore, using the CD4 binding-competent and CD4 binding-defective Env immunogens, we assessed if in vivo CD4 binding affected the outcome of an intravenous SHIV challenge. Antibodies directed against the conserved co-receptor binding site of Env were only observed following immunization with the CD4-binding competent trimers. However, the presence or absence of this class of antibodies did not influence the level of protection against SHIV infection. These results indicate that Env-CD4 in vivo interactions, and specifically co-receptor binding site-directed antibodies, did not contribute to the control of viremia observed in this challenge model.
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