Surface markers on the T cells that regulate cytotoxic T cell responses. II. Distribution of Ly 6.1 and Ly 7.2: selective expression of Ly 7.2 on helper T cell effectors.

Helper T cells and suppressor T cells can be generated in vitro, yielding effector cells with radioresistant function that regulate a cytotoxic T cell response to alloantigen. The Ly 6.1 and Ly 7.2 antigen phenotype of these regulatory effector cells has been determined. Ly 7.2 was found to be selectively expressed on helper T cells; neither the suppressor cells nor the cytotoxic cells analyzed here were found to bear Ly 7.2 antigens. Mixing experiments demonstrated that the helper cell bears both Ly 1.1 and Ly 7.2. Removal of help by anti-Ly 7.2 treatment frequently enhanced suppressor activity. Suppressive activity was partially depleted by treatment with anti-Ly 6.1; helper cell activity was unaffected by such treatment. Cytotoxic T cell precursors bear neither Ly 6.1 nor Ly 7.2, but approximately half of the cytotoxic T cell effectors did bear Ly 6.1; none bore Ly 7.2. Analysis of populations depleted of 7.2-bearing cells should therefore allow the design of experiments that will increase our understanding of the interactions of various regulatory cell populations in the control of a cytotoxic T-cell response.