Changes in anti-A and anti-B antibody titer and A- and B-glicosyltransferase activity were analyzed in five patients after minor ABO-incompatible bone marrow transplantation (BMT). All patients showed complete engraftment after BMT. Shortly after BMT, blood types of recipient's erythrocytes as examined by standard agglutination techniques changed into those of the donor's erythrocytes. Using the elution method, however, recipient's erythrocyte antigens were detected on erythrocytes from three of five patients with complete engraftment after BMT. Analysis of A- and B-transferase activity in serum demonstrated that four of five patients maintained pre-BMT transferase activity. The other patient, who showed no A- or B-transferase activity after BMT, had an inhibitor to this activity. These results suggest that in patients receiving BMT, a small amount of blood antigens on erythrocytes and serum transferase activity may be derived from the patient's tissue.
