| 1. |
- Nylander, Anja, et al.
(författare)
-
An investigation of the interaction between red blood cells and Streptococcus pyogenes
- 2010
-
Konferensbidrag (refereegranskat)abstract
- Blood group antigens may be used as receptors by pathogens when infecting their hosts. Different blood groups therefore can be disease susceptibility factors. Thus, pathogens may have exerted a selection pressure on the evolution of blood group diversity. One aim of our study was to identify red blood cell (RBC) membrane structures that are bound by the common human pathogen. Streptococcus pyogenes, responsible for conditions like pharyngitis, Scarlet fever, necrotizing fasciitis and rheumatic heart disease. We also wanted to explore any differences in the ability of S. pyogenes to agglutinate RBC of different ABO groups and of selected null blood group phenotypes.Solubilized RBC membranes were incubated with different strains of S. pyogenes. RBC proteins that bound to bacteria were eluted and separated by SDS-PAGE. In our initial studies, a strong band at ~58 kDa and a weaker band at ~28 kDa were visualized by Coomassie staining. Subsequent analysis by mass spectrometry and Western blotting revealed the bands to correspond to IgG heavy and light chains. The IgG-related bands were strongest for bacterial strains expressing both protein H and M protein, surface structures known to bind IgG, while weaker or no bands were detected in those strains lacking one or both proteins. Results from subsequent experiments indicated that the interaction between S. pyogenes and RBCs was not limited to IgG, but that a number of other RBC membrane structures appear to bind specifically to S. pyogenes. Those proteins are currently being analysed by mass spectrometry.In agglutination studies of S. pyogenes and RBCs, either sensitised with IgG or stripped of IgG we confirmed that IgG has a role in the binding of RBCs by S. pyogenes. We observed no difference in the ability of S. pyogenes to agglutinate RBCs of different ABO groups, indicating that the ABO-specific differences in RBC surface oligosaccharides are not recognized. When we tested a panel of RBCs with rare null phenotypes we found that cells of the Helgeson phenotype, expressing very low levels of the Knops antigens on complement receptor 1 (CR1), agglutinated more weakly than other common and rare RBCs tested.We are still puzzled by the fact that the hemagglutination is stronger for S. pyogenes strains lacking the M-protein, known to bind both complement and IgG on the surface of the bacteria. Our hypothesis is that there might be some repulsive force acting between the M-protein and surface of RBC, making the interaction stronger when the M-protein is missing. This is supported by agglutination studies with papain-treated RBCs, where the negative charge is reduced.IgG is known to bind senescent cell antigens on erythroid band 3 and thus the amount of IgG increases on the RBC surface as it ages. We speculated that binding to IgG on the RBC surface by S. pyogenes could be a way to selectively target aged RBCs, possibly to acquire heme as a source of iron. Attempts to separate RBCs according to age were made on density gradients, followed by agglutination studies of the different fractions. Our initial results did not demonstrate any conclusive differences. Our data indicate that interactions between S. pyogenes and RBC are mediated at least through IgG and CR1 on the RBC surface. The clinical importance awaits exploration but may be relevant in the identification of resistance factors to infections among humans, and could thus lead to the development of alternative ways to treat infections caused by S. pyogenes.
|
|
| 2. |
- Storry, Jill, et al.
(författare)
-
Homozygosity for a null allele of SMIM1 defines the Vel-negative blood group phenotype
- 2013
-
Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; 45:5, s. 537-U109
-
Tidskriftsartikel (refereegranskat)abstract
- The Vel antigen is present on red blood cells (RBCs) from all humans except rare Vel-negative individuals who can form antibodies to Vel in response to transfusion or pregnancy. These antibodies may cause severe hemolytic reactions in blood recipients. We combined SNP profiling and transcriptional network modeling to link the Vel-negative phenotype to SMIM1, located in a 97-kb haplotype block on chromosome 1p36. This gene encodes a previously undiscovered, evolutionarily conserved transmembrane protein expressed on RBCs. Notably, 35 of 35 Vel-negative individuals were homozygous for a frameshift deletion of 17 bp in exon 3. Functional studies using antibodies raised against SMIM1 peptides confirmed a null phenotype in RBC membranes, and SMIM1 overexpression induced Vel expression. Genotype screening estimated that similar to 1 of 17 Swedish blood donors is a heterozygous deletion carrier and similar to 1 of 1,200 is a homozygous deletion knockout and enabled identification of Vel-negative donors. Our results establish SMIM1 as a new erythroid gene and Vel as a new blood group system.
|
|
| 3. |
|
|
| 4. |
|
|
| 5. |
- Alattar, Abdul Ghani, et al.
(författare)
-
Evidence that CD36 is expressed on red blood cells and constitutes a novel blood group system of clinical importance
-
Ingår i: Vox Sanguinis. - 1423-0410. ; , s. 1-9
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND AND OBJECTIVES: Polymorphic molecules expressed on the surface of certain blood cells are traditionally categorized as blood groups and human platelet or neutrophil antigens. CD36 is widely considered a platelet antigen (Nak a ) and anti-CD36 can cause foetal/neonatal alloimmune thrombocytopenia (FNAIT) in CD36-negative pregnant women. CD36 is used as a marker of differentiation in early erythroid culture. During the experimental culture of CD34+ cells from random blood donors, we observed that one individual lacked CD36. We sought to investigate this observation further and determine if CD36 fulfils the International Society of Blood Transfusion criteria for becoming a blood group. MATERIALS AND METHODS: Surface markers were monitored by flow cytometry on developing cells during the erythroid culture of CD34+ cells. Genetic and flow cytometric analyses on peripheral blood cells were performed. Proteomic datasets were analysed, and clinical case reports involving anti-CD36 and foetal anaemia were scrutinized.RESULTS: Sequencing of CD36-cDNA identified homozygosity for c.1133G>T/p.Gly378Val in the CD36-negative donor. The minor allele frequency of rs146027667:T is 0.1% globally and results in abolished CD36 expression. CD36 has been considered absent from mature red blood cells (RBCs); however, we detected CD36 expression on RBCs and reticulocytes from 20 blood donors. By mining reticulocyte and RBC datasets, we found evidence for CD36-derived peptides enriched in the membrane fractions. Finally, our literature review revealed severe cases of foetal anaemia attributed to anti-CD36.CONCLUSIONS: Based on these findings, we conclude that CD36 fulfils the criteria for becoming a new blood group system and that anti-CD36 is implicated not only in FNAIT but also foetal anaemia.
|
|
| 6. |
|
|
| 7. |
|
|
| 8. |
- Araujo, F, et al.
(författare)
-
Weak D type 2 is the most prevalent weak D type in Portugal
- 2006
-
Ingår i: Transfusion Medicine. - : Wiley. - 0958-7578 .- 1365-3148. ; 16:1, s. 63-67
-
Tidskriftsartikel (refereegranskat)abstract
- The weak D phenotype is the most common D variant, with a frequency of 0.2-1% in Caucasian individuals. There are several weak D types, with different frequencies in European countries, which may pose serologic problems and have the potential for alloimmunization. Samples from Portuguese individuals were tested for RhD by two or three distinct monoclonal and oligoclonal antisera, in direct agglutination tests. When discrepant results were observed, samples were tested with panels of monoclonal anti-D by LISS-indirect antigobulin test. Cases that reacted weakly with IgM but positive with IgG anti-D were analysed by PCR-sequence-specific primers and real-time PCR. Ninety-nine samples were referred after being characterized as weak D. This genotype was recognized, with a preponderance of weak D type 2 (63.6%) over type 1 (16.2%) and 3 (14.1%). The high incidence of weak D type 2 in our population is in marked contrast to studies performed in other European populations and might be due to our sample selection criteria or ethnic variation. There are advantages in genotyping serologically depressed D samples to avoid the waste of D-negative RBC units and the use of immunoglobulin in pregnant women, who have no risk of alloimmunization.
|
|
| 9. |
- Avent, Neil D., et al.
(författare)
-
The Bloodgen Project of the European Union, 2003-2009
- 2009
-
Ingår i: Transfusion Medicine and Hemotherapy. - : S. Karger AG. - 1660-3818 .- 1660-3796. ; 36:3, s. 162-167
-
Forskningsöversikt (refereegranskat)abstract
- The Bloodgen project was funded by the European Commission between 2003 and 2006, and involved academic blood centres, universities, and Progenika Biopharma S. A., a commercial supplier of genotyping platforms that incorporate glass arrays. The project has led to the development of a commercially available product, BLOODchip, that can be used to comprehensively genotype an individual for all clinically significant blood groups. The intention of making this system available is that blood services and perhaps even hospital blood banks would be able to obtain extended information concerning the blood group of routine blood donors and vulnerable patient groups. This may be of significant use in the current management of multi-transfused patients who become alloimmunised due to incomplete matching of blood groups. In the future it can be envisaged that better matching of donor-patient blood could be achieved by comprehensive genotyping of every blood donor, especially regular ones. This situation could even be extended to genotyping every individual at birth, which may prove to have significant long-term health economic benefits as it may be coupled with detection of inborn errors of metabolism.
|
|
| 10. |
|
|
