Hemolysis is a positive agglutination reaction and is primarily associated with high anti-A or anti-B antibody titers. This high titer may result in no agglutination due to the "prozone" phenomenon. Platelet concentrate of high titer has an adverse effect on the recipient of the non-identical ABO blood group. Similarly, the blood products with higher titers of isoagglutinin have recently increased the incidence of intravenous immunoglobulins-related hemolysis. In this Asian subcontinent, the impact of O blood donors with high antibody titers or ABO incompatible platelets is hardly addressed. Blood was collected from two healthy donors and subjected to blood grouping as done routinely. Hemolysis was observed in the reverse grouping with the "B-"cell. Blood grouping was repeated with the conventional tube technique (CTT) where there was no agglutination with the "B"-cell. Suspecting the "prozone" phenomenon, serial dilution of anti-B was done by CTT, and the titer was found to be 1:256 and 1:128 in both cases. Then, the reverse grouping was repeated with a diluted serum (1:8), and the blood group was confirmed to be A RhD-positive and O RhD-positive, respectively. The absence of agglutination in a reverse grouping is not only an indicator of weak antibody but also a presentation of the "prozone" phenomenon. This could be differentiated by doing the titer of isoagglutinin. Hemolysis due to high agglutinin levels should be documented and evaluated, and blood components should be properly labeled to ensure that the product is transfused to the same blood group patients.
Keywords: ABO-incompatible; blood group discrepancy; immunohematology; prozone.
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