1384 Idiotype Specificity of Effector - Phase Suppression

It has been well documented (1-1 1) that the manifestation of immune suppression is the result of interactions among several T lymphocyte subsets. These cellular interactions often depend upon the recognition of unique idiotypic determinants present on the various lymphoid elements (4-11). We have previously (6) characterized one such system in which murine suppressor T cells, which are induced by the intravenous administration of syngenic spleen cells covalently coupled with the 4-hydroxy-3-nitrophenyl acetyl (NP) 1 hapten, specifically affected the responses of NP b idiotype-bearing B lymphocytes both in vivo and in vitro. The ability of these Lytl , Lyt-2 +, Igh-restricted suppressor T cells to bind idiotype and to function during the effector phase of an in vitro response (7) suggested that they corresponded to the effector-phase suppressor T cell (Ts e or Ts2) involved in the suppression of NP-specific delayed-type hypersensitivity and cutaneous sensitivity responses (5, 11). The recognition of idiotypic determinants by suppressor cells appeared then to be important for the regulation of both T and B cell responses. It is well established (12-15) that many defined idiotypic systems are composed of a family of idiotypically related but nonidentical molecules. In the NP b idiotypic system, for example, most monoclonal anti-NP antibodies exhibit only a fraction of serum NP b idiotypic specificities (14). To determine whether T cell receptors recognize the same repertoire of NP b idiotypic determinants as anti-idiotypic antiserum, the ability of effector-phase suppressor cells to bind monoclonal anti-NP antibodies bearing different levels of NP b idiotypic determinants was studied. The results suggest that anti-idiotypic effector-phase suppressor T cells do not recognize the predominant serologically detected NP b idiotypic determinants.