An association between ABO group and HLA antibody detection

US blood centers can screen female plateletpheresis donors with a history of one or more pregnancies for both Class I and Class II anti-HLA antibodies using one of two platforms. One is a flow-based assay that yields a quantitative result and the other an enzyme-linked immunosorbent assay (ELISA) that yields either a positive or a negative result (above or below cutoff).

The results of HLA antibody screening tests were analyzed by donor ABO group. Results from large and small American blood collection centers using both platforms were analyzed. Positivity rates were compared by chi-square test and the results stratified by parity using the Mann-Whitney test.

No differences in parity were noted among donors of different ABO groups, but a significantly higher rate of HLA antibody positivity was observed among group O donors for the ELISA (31% of group O donors vs. 21% of non-group O donors, p < 0.0001). The higher rate of positivity was primarily due to Class I reactivity. This difference in antibody frequency was not observed at centers using the flow-based assay.

Centers using the ELISA may have a higher rate of permanent deferral from plateletpheresis donation among group O female donors. Although the reasons for the higher rate of reactivity on Class I ELISA testing are unknown, this could result from test system characteristics or differences in group O donor antibody strength or specificity.