T cell subset interactions in the regulation of syngeneic tumor immunity

Suppressor T cell (Ts) regulation of immunity to chemically induced syngeneic tumors has been investigated with regard to the mechanism of Ts stimulation and cell-to-cell communication. It has been determined that suppressor cells generated by the presence of tumor antigen participate in a suppressive circuit involving both cells and cell-derived factor(s) in the expression of suppressive effects. Evidence is provided that these interactions occur via idiotype--antiidiotype recognition in a manner similar to those in hapten-specific immune response. Conditions for induction of Ts activity in vivo have been artificially created by a variety of means, including the intravenous administration of soluble antigen and the inhibition of antigen-presenting function by anti-I-A antibodies or by in vivo treatment with ultraviolet irradiation. Suppression appears to be directed against the Ly-1+ cell, which mediates tumor immunity in this system. The summary of evidence suggest that responses to tumor antigen are in many aspects analogous to those occurring in response to more conventional antigens, but are subject to the dampening effects of suppressor cells generated continually during the period of primary tumor growth.