The heterophile transplantation antigen (HT-A) system: a unique heterophile system exhibiting multiple specificities

Although many characteristics o f the heterophile transplantation antigen (HT-A) system have been determined, definitive information regarding certain aspects of the system is still lacking. In an effort to obtain such information concerning the number of HT-antigen and antibody specificities (i.e. single or multiple) and the distribution of HT-A among selected mammalian and avian species, the present study was conducted. In this study, the ability of erythrocytes from several species to absorb the anti-HT-A activity from 6 anti-HT-A sera was determined with a quantitative inhibition of hemagglutination assay utilizing an electronic particle counter. Careful analysis of the results of these experiments indicated the existence of multiple (i.e. 5 or more) HT-antigen and antibody specificities. The distribution of these HT-antigens among selected mammalian and avian species was not identical to the distribution of any well-characterized heterophile antigen of which we are aware. Therefore, none of the HT-A specificities defined in this study are identical to previously described heterophile antigens. These findings confirm and expand previous knowledge of the HT-A system and have facilitated formulation of hypotheses regarding the role of multiple specificities in acute renal allograft rejection and the genetics of HT-A expression in humans.