Evaluation of two methods for detecting anti-A and anti-B hemolysins in blood donors: a prospective study in Abidjan.

Introduction: anti-A and anti-B hemolysins are IgG antibodies capable of causing intravascular hemolysis during non-ABO-identical transfusions, particularly with plasma-rich components. Their identification in blood donors is crucial for transfusion safety. This study aimed to compare the performance of indirect agglutination and functional hemolysis assays in detecting these antibodies.

Methods: we conducted a prospective comparative study involving 300 voluntary blood donors recruited at Cocody University Hospital between January and March 2025. Each sample was tested using two parallel methods: (1) an indirect agglutination assay performed after thermal inactivation of IgM antibodies; and (2) a functional hemolysis test employing guinea pig complement. Hemolysin titers were considered significant if ≥32 for agglutination or ≥8 for hemolysis. Multivariable logistic regression analysis was used to identify independent factors associated with a positive hemolysis test result.

Results: agglutination detected 54 positive cases (18.0%), and hemolysis identified 30 cases (10.0%). Significant titers were found in 7.4% (agglutination) versus 60.0% (hemolysis) of positive cases. Approximately 70% of positive donors were blood group O with either method. Overall concordance between methods was 92% (κ = 0.67). The agglutination method had 100% sensitivity and 91.1% specificity. A history of pregnancy was the only factor significantly associated with a positive hemolysis test (adjusted odds ratio = 2.77; 95% CI: 1.08-7.14; p = 0.033).

Conclusion: the functional hemolysis test more specifically identifies antibodies with potential transfusion risk. In resource-limited settings, targeted screening based on ABO group, antibody titers, and donor immunological history (especially pregnancy) could improve transfusion safety.