Revision summary
A blood group system is a locus of cell-surface antigens. ABO and Rh are red-cell systems for transfusion. HLA is the MHC on leukocytes, used in graft matching. HLA polymorphism dwarfs ABO. Anthropology used both as population markers, not as races.
Model answer
Introduction
A blood group system is a set of antigens on blood cells, inherited at one genetic locus or cluster, that can raise antibodies. ABO and Rh are red-cell systems. HLA is a white-cell system of a different biological job.
Body
Red-cell systems
- Landsteiner found ABO. Rh, MN, Duffy, and others followed. They sit on erythrocytes and matter in transfusion and haemolytic disease of the newborn.
- Anthropology used ABO maps, after Hirszfeld and Boyd, as population markers. They are poor race types.
HLA
- Human Leukocyte Antigen genes sit in the MHC on chromosome 6. They present peptides to T cells. Matching them matters in graft survival, not in ordinary packed-red-cell transfusion.
- HLA is vastly more polymorphic than ABO. That diversity is immune history, including pathogen pressure.
- Disease associations (ankylosing spondylitis and HLA-B27) have no ABO parallel in strength.
Contrast
- Red-cell groups are mostly carbohydrate or protein badges on the erythrocyte. HLA is an immune recognition system on leukocytes and tissues.
- Both are genetic polymorphisms. Only HLA is the transplant barcode.
Flow diagram
flowchart TD BG[Blood groups] --> RC[Red cell ABO Rh] BG --> HLA[MHC white cell] RC --> TR[Transfusion] HLA --> TX[Transplant immunity]
Conclusion
Blood group systems are inherited antigen families. Red-cell systems guide transfusion. HLA guides immunity and transplantation and is not a red-cell blood group in the Landsteiner sense.
Quick related
Students also ask
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Rh-Blood Group
Next question on this syllabus topic (2016 · Q5(a)). View answer →
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Do we match HLA for every blood transfusion?
No. Packed red cells follow ABO and Rh. HLA matters for platelets, marrow, and organs.
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Is HLA a blood group?
In a wide sense it is a leukocyte antigen system. In exam contrast, it is not a red-cell group.
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Q5(a) · UPSC Mains 2016 · Anthropology GS 1 · 10 marks
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Rh groups centre on the D antigen. Positive means D present; negative means D absent. An Rh-negative mother can be sensitised by an Rh-positive fetus. Anti-D prophylaxis prevents most haemolytic disease. Frequencies differ by population, as a polymorphism.
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