Positive antiglobulin tests due to intravenous immunoglobulin in patients who received bone marrow transplant

To investigate an increased frequency of positive direct (DAT) and indirect (IAT) antiglobulin tests in bone marrow transplant (BMT) patients who received intravenous immunoglobulin (IVIG), serologic testing was performed weekly on blood samples from 94 consecutive BMT patients. Group 1 (47 patients) did not receive IVIG. Group II (47 patients) received high-dose IVIG as prophylaxis for cytomegalovirus infections. Before transplantation no alloantibodies were found in the serums of 92 patients and anti-E was found in the serums of two patients. DATs were negative in all patients before BMT. Four percent of Group I had a positive IAT and 13 percent had a positive DAT. In contrast, 25.5 percent of Group II patients had a positive IAT and 49 percent had a positive DAT, usually within 1 week after initiation of IVIG therapy (p less than 0.001). Antibodies identified in serums and eluates of patients in Group I were anti-A and anti-B. Antibodies identified in serums and eluates of patients in Group II were anti-A, -B, -D, and -K. Twenty-one lots of IVIG were tested and antibodies identified were anti-A, -B, -D, and -K. The data suggest that the higher frequency of positive serologic tests in Group II was due to passively acquired antibodies from high-dose IVIG.