RBC alloantibody specificity and antigen potency in Olmsted County, Minnesota.

BACKGROUND: While RBC antigen frequencies for whites of Northern European ancestry are known, the relative frequencies of RBC antibodies within this population 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 population. STUDY DESIGN AND METHODS: RBC alloimmunization among patients and donors in Olmsted County, MN, was determined for the period from 1975 to 1995. Alloantibody frequencies were used to calculate the potency of each antigen relative to K. Cluster analysis was applied to the data to identify natural groupings of antibodies. RESULTS: The frequency and potency of 33 alloantibodies from 1345 alloimmunized 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), Kp(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 frequent 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 showed grouping of the antibodies to C and D as well as to Le(a) and Le(b), but the other RBC alloantibodies did not form clusters. CONCLUSION: Less than 1 percent of residents tested had positive antibody screens. Anti-E and anti-Le(a) were more common than anti-K. Wr(a) and C(w) were more potent antigens than K. Most antibodies showed an increase in frequency with increasing age. Except for anti-C and -D and anti-Le(a) and -Le(b), RBC alloantibodies did not occur in clusters.

Trends in the incidence of delayed hemolytic and delayed serologic transfusion reactions.

BACKGROUND: An increasing incidence of delayed hemolytic and delayed serologic transfusion reactions (DHTRs/DSTRs) has been seen at the Mayo Clinic since 1978. Recently, the average length of stay (LOS) for inpatients and the average number of red cell transfusions per inpatient (TPI) decreased, and the albumin and papain technique for RBC antibody detection was replaced by a polyethylene glycol technique. These changes may have affected the incidence of DHTRs/DSTRs. STUDY DESIGN AND METHODS: The diagnoses of DHTR and DSTR made at the Mayo Clinic from 1993 through 1998 were reviewed. These data were compared with previously published Mayo Clinic data from 1980 through 1992. The LOS for inpatients and the average TPI were also obtained from hospital data. RESULTS: The incidence of DHTR/DSTR increased from 1 in 1899 in 1980 through 1992 to 1 in 1300 in the 1993 through 1998 period (p < 0.05). Similarly, DSTR increased from 1 in 2990 in 1980 through 1992 to 1 in 1612 in the 1993 through 1998 period (p < 0.05). The incidence of DHTR showed a trend toward decrease, from 1 in 5405 in 1980 through 1992 to 1 in 6715 in 1993 through 1998. No alloantibody specificities were statistically associated with DHTRs in 1993 through 1998, unlike in the 1980 through 1992 period. Moreover, the incidence of Jka antibodies increased in 1993 through 1998, while the incidence of other alloantibodies remained stable. Average LOS and TPI declined by 24.5 percent and 8.8 percent, respectively, between the two periods. CONCLUSION: Recently, a trend toward a decrease in the incidence of DHTR and a significant increase in DSTRs has occurred at the Mayo Clinic. These changes are most likely due to a combination of factors, including a decrease in average LOS and the adoption of the polyethylene glycol antibody detection system.