Regulation of hapten-specific T-cell response. II. Functional analysis of helper T cells and cytotoxic T cells in animals suppressed by azobenzenearsonate (ABA)-specific suppressor T cells.

The administration of azobenzenearsonate-modified syngeneic spleen cells (ABA-SC) intravenously induces a population of first order hapten-specific inducer suppressor T cells (Ts1), which downregulate various aspects of T-cell-mediated immune responses via a well defined suppressor-T-cell pathway. In this study, we investigated the effects of these suppressor cells on the generation of ABA-specific cytolytic T lymphocytes (CTL) and helper T cells (Th) in vivo. We found evidence for functional impairment of ABA-activated Th and ABA-specific CTL precursors (CTLp) in the suppressed animals by a number of different in vitro criteria. Functional analysis of ABA-specific CTLp and ABA-activated Th in suppressed animals revealed that ABA-specific Ts inhibit the generation of CTL by impairing the antigen-specific activation of Th, which may in turn, prevent the clonal expansion of antigen-specific CTLp. The significance of these findings in relationship to our understanding of the cellular interactions necessary for the generation of CTL and the mode of action and mechanisms of suppressor T cells is discussed.