Suppressor T-cell memory

Abstract

MEMORY is a fundamental characteristic of immunological phenomena; it is manifested by enhanced responsiveness upon re-exposure to antigen, and its specificity forms the basis of the clonal selection concept. In collaborative antibody responses the development of memory has been demonstrated in both the T helper (T_H) cell and the B cell populations¹, whereas in cell mediated reactions such as delayed hypersensitivity, allograft rejection, cytotoxicity and graft-versus-host responses, memory is a property of the T cell subpopulation mediating each type of response. Specific suppression of antibody production by a subpopulation of T cells is now well documented^2–4. The importance of suppressor T (T_s) cells in immune homeostasis is highlighted by their demonstration during normal immune responses⁵ as well as following tolerance induction⁶. After primary immunisation, however, T_s cells are detectable for only a limited period of time and do not prevent the emergence of long-lived T_H and B memory cells. The parallel development of memory T_s cells would therefore be highly advantageous if these cells are to be effective in the regulation of secondary immune responses. Furthermore, the potential value of T_s in the maintenance of active tolerance to self antigens would be enhanced if a pool of memory cells existed which could be rapidly recruited to abort incipient autoimmune responses. The experiments reported here demonstrate the presence of specific long lived memory T_s cells in mice exposed to the protein antigen, human γ-globulin (HGG).