RBC alloantibody specificity and antigen potency in Olmsted County, Minnesota

BACKGROUND: While RBC antigen frequencies for whites of Northern European a ncestry are known, the relative frequencies of RBC antibodies within this p opulation have not been determined. The distribution of RBC alloantibodies by sex and age was studied, as were the immunogenicity of RBC antigens and the occurrence of RBC alloantibody clusters in a geographically defined pop ulation. STUDY DESIGN AND METHODS: RBC alloirnmunization among patients and donors i n Olmsted County, MN, was determined for the period from 1975 to 1995. Allo antibody frequencies were used to calculate the potency of each antigen rel ative to K. Cluster analysis was applied to the data to identify natural gr oupings of antibodies. RESULTS: The frequency and potency of 33 alloantibodies from 1345 alloimmun ized subjects were estimated. The most frequent alloantibodies were E (20.8 %), Le(a) (18.6%), K (14.7%), D (12.9%), Le(b) (9.4%), M (7.2%), P-1 (6.7%) , Fy(a) (6.3%), C (6.8%), and c (3.5%). The most potent antigens were Wr(a) (0.363), C-w (0.078), Le(a) (0.03), E (0.028), V (0.025), Js(a) (0.023), K p(b) (0.023), Go(a) (0.023), JMH (0.023), and Rd (0.023). Greater frequency of overall alloimmunization (M:F = 1:2.7), anti-D (p <0.0001), and anti-Le (a) (p = 0.003) was seen among females. Warm autoantibodies were more frequ ent among males with positive antibody screens (p <0.0001). No other gender differences were observed. Alloimmunization increased with age for K, Kp(a ), Fy(a), D, C, E, and warm autoantibodies. Frequencies of alloimmunization to Le(a), Le(b), M, and P-1 decreased with age. The cluster analysis showe d grouping of the antibodies to C and D as well as to Lea and Leb, but the other RBC alloantibodies did not form clusters. CONCLUSION: Less than 1 percent of residents tested had positive antibody s creens. Anti-E and anti-Lea were more common than anti-K. Wr(a) and C-w wer e more potent antigens than K. Most antibodies showed an increase in freque ncy with increasing age. Except for anti-C and -D and anti-Le(a) and -Le(b) , RBC alloantibodies did not occur in clusters.