IMMUNOHEMATOLOGY: The characterization and classification of concurrent blood group antibodies

BACKGROUND: Concurrent alloantibodies are defined as two or more blood group (BG) antibodies coexisting in a given patient. These antibodies are significant because they can present major problems in compatibility testing. The goals of this study were to determine the properties of concurrent BG antibodies. STUDY DESIGN AND METHODS: The transfusion records of 18,750 patients at a Veterans Affairs medical center were reviewed to identify alloimmunized individuals. The following data were collected on patients making concurrent antibodies: antibody specificities, time of first detection, whether the antibodies disappeared over time, and, if so, their time of disappearance. RESULTS: Multiple alloimmunization occurred in 21.7% (96/443) of alloimmunized patients, constituting 39.9% (230/577) of all antibodies. The rate at which an antibody was concurrent with another antibody varied by antigenic specificity (p < 0.05). Anti-C (21/28; 71.4%) and anti-c (19/27; 70.4%) were most likely to coexist with another antibody, while anti-P(1) (3/22; 13.6%) and anti-M (3/18; 16.7%) were least likely. The most common alloantibody pairs were anti-K/-E, anti-D/-C, and anti-E/-c. Paired antibodies were initially detected in the same antibody screen in most cases. The majority of antibody pairs were either both persistent or both evanescent. When they were evanescent, both antibodies usually became undetectable at the same time. The persistence over time of concurrent alloantibodies (70.4%) was not higher than that of antibodies occurring singly (67.5%; p = 0.63). CONCLUSIONS: Antibody concurrence varied by BG antigenic specificity. Paired BG antibodies tended to appear and disappear in a coordinated fashion. Concurrent alloimmunization had no effect on antibody persistence.