The Frequency and Distribution of Unexpected Red Cell Antibodies and Analysis of Antigen Exposure

Red cell alloantibodies other than naturally occurring anti-A or anti-B are called unexpected red cell antibodies, and can be detected by performing an antibody screening. The frequency and distribution of unexpected antibody identified in Asan Medical Center were analyzed. We investigated a total of 135,238 cases of antibody screening test in AMC for 3 years from 2010 to 2012. Using column agglutination techniques, antibody identification tests were performed for the cases with positive antibody screening. Among 135,238 cases, 854 (0.6%) cases showed positive results of antibody screening test. In the order of frequency, 284 (33.3%) anti-Rh, 89 (10.4%) anti-MNS, 62 (7.3%) anti-Lewis, 34 (4.0%) anti-Kidd, 10 (1.2%) anti-Duffy, and 9 (1.1%) anti-P were identified. Multiple antibodies were detected in 199 (23.3%) cases. Among 381 subjects investigated for transfusion history, 299 (78.5%) had history of transfusion while 82 (21.5%) had unknown history. Thus the incidence of unexpected antibody was higher in the group with history of transfusion than the group without (p<0.001). Also, among 435 subjects investigated for the history of pregnancy, 46 (10.6%) had no history while 389 (89.4%) had history of pregnancy, showing higher incidence of unexpected antibody in the group with history of pregnancy than the group without pregnancy (p<0.001). Evaluated amounts and frequency of antigen exposure due to transfusion and pregnancy is suggested to increase the frequency of identification of unexpected antibody.