SUPPRESSOR T-CELL MECHANISMS IN CONTACT SENSITIVITY .2. AFFERENT BLOCKADE BY ALLO-INDUCED SUPPRESSOR T-CELLS

Abstract

The mechanism(s) by which MHC[major histocompatibility complex]-restricted suppressor T [thymus derived] cells (Ts) induced by i.v. injection of allogeneic DNP[dinitrophenyl]-modified lymphoid cells (alloinduced Ts) suppress the DNFB [dinitrofluorobenzene] contact sensitivity response was investigated. Alloinduced Ts acted only during the early phases (afferent limb) of sensitization. They were incapable of suppressing previously sensitized recipients or of inhibiting the expression of DNFB-immune LN [lymph node] cells when co-transferred into normal recipients. The target of alloinduced Ts seems to be cell proliferation, i.e., inhibition of antigen-induced cell proliferation (DNA synthesis) in Ts recipient mice. The failure of recipients of alloinduced Ts to generate DNFB-immune LN cells capable of transferring contact sensitivity to normal recipients also suggests that these Ts act by preventing the development of an expanded clone of mature immune T cells. The suppressive effects of alloinduced Ts also were inhibited by prior in vitro treatment with anti-TNP [trinitrophenyl] serum. The data are discussed in terms of current models of suppression, and are compared to mechanisms of suppression in other contact sensitivity models.