Definition: Major incompatibility refers to the presence of naturally occurring antibodies in the recipient against the donor’s A and/or B blood group antigens, which may cause hemolysis of the red blood cells contained in the transplanted product. Minor incompatibility refers to the presence of anti-A and/or anti-B antibodies in the donor’s hematopoietic stem cell (HSC) product against the recipient’s A and/or B blood group antigens.
Reason: In major incompatibility, either the red blood cell content of the graft should be reduced or the recipient’s antibody titer should be lowered to <1:16 to prevent an acute hemolytic reaction. In minor incompatibility, the plasma content of the graft should be reduced to prevent an acute hemolytic transfusion reaction.
Therapeutic plasmapheresis can reduce the ABO antibodies responsible for hemolysis. In major ABO incompatibility, if red blood cells cannot be depleted from the graft, removal of high-titer antibodies from the recipient’s circulation may prevent hemolysis. In minor ABO incompatibility, where passenger lymphocytes produce antibodies 7–12 days after infusion, prophylactic exchange transfusion with group O red blood cells may be performed to reduce the recipient’s erythrocyte population.
Procedure: TPE, DFPP, CF
Processed Volume: 1–2 TPV
Frequency: Daily
Replacement Fluid: Albumin, FFP, HES
Number and/or Duration of Procedures: Before transplantation, IgM and IgG antibody titers should be rapidly reduced to ≤1:16. In most cases, 2–4 procedures are sufficient. If erythroid recovery is delayed or in cases of pure red cell aplasia (PRCA), and antibody titers remain high, additional procedures may be performed during the post-transplant period.