ANTI-A AND OR ANTI-B IS NOT DETECTABLE IN SOME PATIENTS WHO UNDERWENTABO-INCOMPATIBLE BONE-MARROW TRANSPLANTATION/

Background: Recently, anti-A and/or anti-B produced by B cells from do nor marrow could not be detected for more than 20 weeks in some patien ts who had undergone ABO-incompatible bone marrow transplantation (BMT ). Study Design and Methods: Twelve to 72 weeks after 11 patients unde rwent ABO-incompatible BMT, titers of anti-A and anti-B were assayed, A and B antigens were identified by routine methods and flow cytometry , direct and indirect antiglobulin tests were performed, and the red c ell antibody was eluted. Results: In some patients who underwent ABO-i ncompatible BMT, anti-A and/or anti-B produced by the B cells from the donor marrow could not be detected after BMT when red cells taken fro m the patients before BMT carried the corresponding antigen-that is, w hen hematopoiesis had already changed the cells to the donor's type ac cording to ABO blood typing. Furthermore, some blood samples from thos e patients gave positive results in direct antiglobulin tests. Blood t yping of patients after BMT showed mixed-field agglutination. In one p atient, the half-life of red cells assayed with Cr-51 was 22.4 days (3 0.0 +/- 4.0 days for normal controls). Conclusion: Although many hypot heses could be considered to explain the present data, the possibility is proposed that anti-A and/or anti-B in the sera must have been cons umed in some patients who underwent ABO-incompatible BMT. This may lea d to problems such as difficulty of ABO typing, positive direct antigl obulin tests, and a relatively short life span of red cells.