Which blood group system is most commonly associated with delayed hemolytic transfusion reactions?

The Kidd blood group system is indeed the one most commonly associated with delayed hemolytic transfusion reactions. This is largely due to the nature of the antibodies that can develop against Kidd antigens.

The Kidd antigens are part of a system that is known for its ability to elicit antibody production in some individuals after transfusion, particularly if they have previously been sensitized. The antibodies, specifically the anti-Jka and anti-Jkb types, are often IgG in nature and can be undetectable early on, only to produce a delayed immune response possibly days to weeks after transfusion. This delayed response can result in hemolysis of red blood cells, manifesting as a delayed hemolytic transfusion reaction.

In contrast, the Lewis, MNS, and I blood group systems are not as frequently involved in chronic sensitization and delayed hemolysis. The Lewis system primarily involves non-red cell-associated antibodies that typically do not result in hemolytic transfusion reactions, while the MNS system’s antibodies are also less immunogenic in the context of delayed reactions. The I antigen, which is variable on red blood cells, plays a role more commonly in cold agglutinin disease than in delayed transfusion reactions.

Therefore,