Which transfusion reaction is most associated with anti-HLA antibodies in the recipient?

• A. Febrile non-hemolytic transfusion reaction
• B. TRALI
• C. Platelet refractoriness due to anti-HLA antibodies
• D. Anaphylaxis

Answer: (C)

Anti-HLA antibodies in the recipient lead to platelet refractoriness because the antibodies target HLA antigens on donor platelets. When platelets carrying these antigens are transfused, the antibodies bind them and mark them for rapid destruction, so the expected rise in platelet count after transfusion is blunted or absent. This results in ongoing bleeding risk despite transfusion.

This scenario is common in patients who have been exposed to foreign HLA antigens through prior transfusions or pregnancies and is diagnosed by observing a poor post-transfusion platelet count increment, sometimes across multiple transfusions. To manage it, clinicians use HLA-mal matched or crossmatch-compatible platelets, or platelets with fewer shared HLA antigens, and may employ treatment strategies to suppress alloimmunity in selective cases.

Febrile non-hemolytic reactions are usually due to cytokines or donor leukocytes and are not specifically caused by recipient anti-HLA antibodies. TRALI is driven by donor anti-HLA or anti-neutrophil antibodies causing acute lung injury in the recipient, not platelet refractoriness from the recipient’s own antibodies. Anaphylaxis is an IgE-mediated reaction to plasma proteins and is unrelated to anti-HLA antibodies.