Abstract

The main points that I have put forth are that: (1) suppressor T cell activity cannot be explained as simply being too much help; (2) feedback signals from target cells are of crucial importance in determining and maintaining the activity of suppressor T cells; (3) whenever T cells are triggered by antigen, suppression occurs. Immune responses only occur when countermanding signals are also generated. Both intrinsic and extrinsic adjuvanticity is the operational production of countermanding signals; (4) memory T cells are qualitatively different from normal T cells in their sensitivity to feedback signals and also in their susceptibility to suppression; (5) mature thymus dependent B cells cannot be rendered tolerant by the direct action of antigen, while immature and thymus independent B cells can; (6) the mechanism of suppression induced by exogenously administered antigens and that by normal differentiation products (i.e.: GVH; allotypes), is different; (7) generation of suppressor cells requires or results from complex interactions between subpopulations of cells, making it impossible under present conditions to determine which cell is doing what and to which; (8) further work is required before a full understanding of the importance, mechanism of action and other aspects of suppressor T cell function can be fully understood.