BACKGROUND: A person exposed to foreign blood group antigens may produce antibodies. The persistence of antibodies varies among people and among antibodies. A study was performed to investigate the persistence of clinically significant RBC alloantibodies over a period of 20 years.
STUDY DESIGN AND METHODS: A retrospective examination was performed of all records of RBC antibodies in the transfusion laboratory computer database from 1978 through 1997. Records of patients who underwent at least one antibody investigation after an antibody had been detected were studied. The study included all antibodies against the Rh, K, Fy, Jk, and MNs blood group systems. An antibody was regarded as not persistent if, after previous detection, the screening or panel studies became negative for the antibody under study. Anti-D due to RhIg administration was excluded.
RESULTS: An analysis was performed of 480 records consisting of 593 antibodies that fulfilled the criteria. Median antibody follow-up was 10 months (range, 1-240). In 137 patients, 153 (26%) antibodies became undetectable over the course of time. After initial negative screening investigations, 310 antibodies were formed. The antibodies that were still detectable had a median follow-up of 7 months (range, 1-193). A patient's age, sex, and antibody specificity were of no influence on the length of time that antibodies were detectable. Antibodies detected with a more sensitive screening technique were less persistent (p = 0.0002). For 28 patients, detection of antibodies was highly irregular.
CONCLUSIONS: About 25 percent of all antibodies became undetectable over the course of time. The antibody screening technique used, rather than the antibody specificity, affected these results. To prevent delayed hemolytic transfusion reactions, precise antibody documentation is of great importance.