Major ABO-Incompatible Hematopoietic Stem Cell Transplant
A 45-year-old man with AML in first remission undergoes allogeneic PBSCT from his HLA-matched brother. The donor is group A and the recipient is group O (major ABO mismatch). The recipient's pre-transplant anti-A titer is 1:128. The graft product has a volume of 200 mL and a hematocrit of 25%, giving a red cell volume of about 50 mL. On day +8, the patient has Hb 6.9 g/dL, platelets 15 × 10^9/L, and fever. The blood bank has group O and A RBCs, group A and AB plasma, and group O and A platelets.
1. Should the graft be modified before infusion?
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Yes. This is a major ABO mismatch because the recipient has anti-A against donor A RBCs. Reduce the red cell content of the graft, typically by RBC depletion, to limit hemolysis from recipient isohemagglutinins. Plasma reduction is not the primary need for a major mismatch; it is used for minor mismatch. If the product cannot be adequately RBC-depleted, consider washing under the institutional protocol. Document the final red cell volume and monitor for hemolysis during and after infusion.
2. Select RBC, platelet, and plasma products for day +8 and explain the rationale.
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Use group O RBCs until donor RBC engraftment is documented and recipient anti-A is no longer detectable; group A RBCs could be hemolyzed by circulating anti-A. Use AB plasma to avoid adding anti-A or anti-B. Prefer group O platelets; if group A platelets are used, ensure they are suspended in AB plasma and follow institutional HSCT protocols. All cellular products should be leukoreduced and irradiated per transplant protocol. Monitor for hemolysis and transfusion reactions.
3. What laboratory monitoring guides the transition from group O to donor-type A RBCs?
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Monitor anti-A isohemagglutinin titers, donor/recipient RBC chimerism, DAT, and hemolysis markers. Transition to group A RBCs only when anti-A is undetectable and donor-derived A RBCs are established. Continue to verify compatibility with the patient's current serologic status, because titers can fluctuate. Document the transition criteria in the transfusion record and communicate them to the clinical team.