Isohemagglutinin Titers and Clinical Significance in Blood Bank Donors: A Single-Center Cross-sectional Cohort Study

Background: Isohemagglutinins directed against ABO blood group antigens play a crucial role in transfusion and transplantation. Understanding the distribution of isohemagglutinin titers in blood donors is critical, particularly in ABO-incompatible hematopoietic stem cell transplantation (HSCT). Objectives: The present study aimed to investigate the distribution of anti-A, anti-B, IgM, and IgG titers among healthy blood donors stratified by blood group, sex, and age. Methods: In this cross-sectional study, isohemagglutinin titers were measured in 1005 randomly selected donors (335 A, 335 B, and 335 O) at a single center. Titers were evaluated using the column agglutination technique, and statistical analyses were used to compare titer distributions by sex and age group. Results: The majority of donors were male (95.2%). Elevated anti-B IgM and IgG titers were significantly more common among female donors, particularly at 1:128 and 1:256 levels for IgM (P = 0.027; P = 0.012) and at the 1:1024 level for IgG (P = 0.005). The overall distribution of the ABO and Rh blood groups in this cohort was consistent with that reported in previous Turkish studies. Conclusions: Female donors demonstrated a tendency toward higher isohemagglutinin titers, although the small number of female participants limited definitive conclusions. These findings emphasize the need to screen high-titer donors, especially in the context of ABO-incompatible HSCT, and suggest that future longitudinal studies incorporating detailed immunologic histories are warranted.