A clinically significant erythrocyte antibody detectable only by 51Cr survival studies.

Hemolytic transfusion reactions typically are explained by red cell serologic incompatibilities. We describe a patient in whom a clinically significant red cell alloantibody could not be demonstrated, despite the occurrence of several clinically severe hemolytic reactions. Serologic studies using multiple techniques demonstrated only an anti-Bga; these studies included standard procedures as well as more sensitive experimental techniques. A 51Cr survival study using red cells from a random unit, compatible in vitro with conventional techniques, showed 72 percent survival at 1 hour and 7 percent survival at 24 hours. R2R2 (hr" (e) negative) red cells in a second 51Cr survival study showed 90 percent survival at 1 hour and 92 percent survival at 6 hours. The patient was transfused with R2R2 units which were tolerated well and survived normally. Extensive serologic testing still demonstrated only an anti-Bga. A third 51Cr survival study, 10 months after the first study, with an R1R1 (hr" (e) positive) sample showed 90 percent survival at 1 hour and 42 percent survival at 6 hours. A fourth study using a larger aliquot of R2R2 (hr"(e)negative) 51Cr-labeled red cells, examined over 2 weeks showed a near normal 21-day survival of 50 percent. These 51Cr survival studies, along with normal survival of hr" (e) negative units, suggest that this patient destroys hr" (e) positive red cells despite negative serologic testing.