Cross-reactive T-cell antigens among mammalian species.

Fluoresceinated heteroantisera prepared against T cells of rats, monkeys, and humans were reacted withthymus and spleen cells from 11 selected species. These reagents recognized cross-reacting T cell antigen(s) among rodent species (mouse, rat, guinea pig, and hamster) and among primate species (monkey and humans). With one exception, the cross-reactivity was restricted to a phylogenetic order. All three antisera required relatively few absorptions to achieve T cell specificity for related species when compared to absorption requirements for the isologous species. Differentiation antigens within a phylogenetic order thus appear to be more homologous than other cell surface constituents on T cells.