Biochemical Basis of Antigen-Specific Suppressor T Cell Factors: Controversies and Possible Answers

Abstract

The chapter reviews previous observations made on T-suppressor factor (TsF) and provides interpretations for controversial issues on this factor. Antigen-specific T cell-mediated immunosuppression could be transferred from one animal to other syngeneic animals either with intact suppressor cells or with soluble factors derived from the cells. The chapter also discusses the experiments that provide the evidence that OVA-specific glycosylation inhibiting factor (GIF), which is an effector type TsF, consists of the 55-kDa TCRa chain-GIF conjugate and the TCRP chain. After the identification of T cell receptors (TCR) on helper and cytotoxic T cells, however, fundamental questions can be raised on T cell-mediated suppression with the failure to identify TCR and TCR gene rearrangement in representative Ts hybridomas. In addition, the ability of Ts cells and antigen-specific TsF to bind specifically to nominal antigen, independently of major histocompatibility complex (MHC) gene products, created skepticism on the nature of Ts cells and the origin of TsF.