An animal model for delayed hemolytic transfusion reactions

Delayed hemolytic transfusion reactions (DHTRs) are a well-known complicati on of transfusion that may be defined as immune-mediated hemolysis of allog eneic donor red cells that occurs approximately 3 to 5 days after transfusi on. In general, DHTRs occur in patients who have been alloimmunized previou sly, but the antibody titers have fallen below serologically detectable lev els. Transfusion of seemingly compatible blood and exposure to the putative alloantigen results in an anamnestic immune response that may lead to in v ivo accelerated destruction of donor red cells. Symptoms may include a drop in hemoglobin and hematocrit, fever, jaundice, and renal insufficiency. Mo re recent studies have shown that there is a subset of cases called delayed serologic transfusion reactions (DSTRs) when there are serologic findings consistent with DHTRs but no clinical evidence of hemolysis. In both DHTRs and DSTRs, direct antiglobulin tests are often persistently positive long a fter the transfused donor red cells should have been removed from the circu lation. Because the studies required to investigate the immunologic and cli nical aspects of these reactions are precluded in humans, we developed an a nimal model for the study of DHTRs and DSTRs. Our article provides a compre hensive review of DHTRs and DSTRs, the role of complement and cytokines in these reactions, and the phenomenon of bystander hemolysis. We describe our studies using the rabbit as a model for the study of DHTRs and bystander h emolysis. Copyright (C) 2001 by W.B. Saunders Company.