Problems in determing A2B group specific properties in blood stains.

Blood stains belonging to various sub-group A combinations were examined by the absorption-elution method (in comparison with Holzer method and mixed agglutination). No difficulties were encountered in the identification of A1, A2, and A1B blood stains, while identification of A antigen in A2B stains was dubious (always negative with the others methods). This seems to be due to low anti-sera titer in relation to A antigen in this subgroup combination.