Cross Reactions of HL‐A Antibodies. VI. Dissection of a Complex Serum

A series of 23 platelet absorptions and elutions were performed with a broadly reactive HL–A antiserum, Tuckerman. This multispecific reagent could be separated into three components: anti‐HL–A1 (10,11); anti‐W23 (W24) and anti‐HL–A12.2 (12.1,13). Each component was examined in detail, revealing some of the intricacies of the specific and cross‐reacting antibodies. A possible subdivision of HL–A12 followed the observation that platelets from certain HL–A12 donors failed to absorb anti‐HL–A12 cytotoxins, even against their own lymphocytes. These absorptive deficiencies were inherited with the HL–A12 genotype. Subdivision of HL–A9 was primarily along racial lines. Antigen W23 predominated among subjects of Negro or Mediterranean ancestry, while specificity W24 was found among donors of the Caucasian and Oriental races.