ANTIGEN-SPECIFIC SOLUBLE SUPPRESSOR FACTOR (S)

Abstract

Publisher Summary This chapter discusses antigen-specific soluble suppressor factors. A number of investigators have described antigen-specific soluble factors (TsF), which suppress either the antibody response, DTH, or the generation of cytotoxic lymphocytes. All of these factors appear to share a number of biological and chemical characteristics: They are derived from T cells, are antigen specific, have a M.W. in the region of 70,000, bear Ia markers (usually associated with the I-J subregion), and do not bear standard Ig markers. In certain systems, antigen-specific suppressor factor(s) can be produced that suppress the in vitro generation of cells cytotoxic for a syngeneic tumor cell (P815 in DBA/2 mice). The factor clearly acts by prohibiting an event early in the generation of cytotoxic cells as its addition to cultures 48 hr after their initiation will no longer prohibit the generation of cytotoxic cells. A model for the mechanism by which the TsF functions has been provided. Preliminary evidence in laboratory indicates that prior exposure of TsF to antigen enhances the efficiency of TsF, whereas prior exposure of prekiller cells to antigen does not. The implication is that the antigenic determinant recognized by the TsF may be distinct from that recognized by the target. If simultaneous interaction between macrophage, antigen, and T helper cell are required for helper cell activation, one could conceive of the macrophage as a target at the instant at which it presents the antigen-TsF complex to the T helper cell precursor; however, in functional terms, one can still consider the T helper cell precursor as the target.