Abstract � Background and Objectives The aim of the present study was to evaluate red blood cell chimerism after bone marrow transplantation by flow cytometry. � Materials and Methods In order to perform this assay, FITC labeled antibodies against blood groups ABH, Rh, Kell, Duffy, Kidd, MNS were used.14 hematologic patients under BMT were selected for this study. The required sample was 5 ml peripheral blood that is collected in tubes containing EDTA. At first, donor and recipients red cells phenotypes were identified with the use of both agglutination and flow cytometry methods then, on post-transplantation days of 15, 30 and 60, only blood samples of the recipients were analyzed by flow cytometry for the antigens differing from donors to recipients. Antibody screening test and titration of ABH Isohemagglutinins were performed on recipients' plasma samples and then repeated on post- transplantation day of 60. � Results After BMT, red cell chimerism was detected in all 14 patients (in 9 patients on post-transplantation day of 15 and in 5 patients on day of 30). Antibodies against minor blood groups and Rh blood group were not detected at all. The occurrence of chimerism was not inhibited by ABO incompatibility of donors and recipients but in patients who were ABH incompatible with their donors, ABH isohemagglutinins titer following transplantation decreased. Although the presence of isohemagglutinins did not prevent chimerism but it seems these antibodies by attaching to their related antigens on chimeric red cells membrane prevented corresponding antigen detection. � Conclusions Now by using flow cytometry, red cell phenotyping is applicable and reticulocyte analysis is much easier to perform so that chimerism can be detected in patients who have recently experienced blood transfusion. Moreover, through further evaluation of red cell chimerism and detection of recipient autologous red cells, disease relapse can be predicted. � � Key words: Bone Marrow Transplantation (BMT), Chimerism, Red cells, Blood group antigens, Hematological disorders |
