The fine specificity of immune suppression to individual nucleosides.

The fine specificity of immune suppression was further studied in a murine experimental model in which the induction and expression of suppression by individual nucleoside-bound spleen cells were examined. The experiments were undertaken: a) to determine whether all 4 nucleosides have the ability to elicit suppressor T cells; b) to examine the specificity of cross-suppression induced by individual nucleosides; and c) to establish that nucleoside-specific suppression is mediated by T cells bearing nucleoside-specific receptors. The results show that, of the 4 nucleosides studied, only guanosine and thymine riboside were capable of eliciting immune suppression. Thymine riboside-coupled spleen cells induced cross-suppression to all 4 nucleosides. Furthermore, the nonresponsive state generated by guanosine-spleen cells was found to be transferable and mediated by nucleoside-binding T cells. The ability of only select nucleosides to elicit immune suppression is discussed in the context of recent evidence demonstrating the selective activation of T cell subsets by intramolecular antigenic determinants.