A suppressor cell in the response of rabbit T cells to Con A

The response to Concanavalin A is regulated by a helper cell, described elsewhere (4), and by a suppressor cell, described in this paper. This suppressor cell is an adherent T cell with Fc receptors. Evidence for properties of the suppressor cell was obtained by two types of experiments: 1) regulatory cells gave more help if Fc-bearing subpopulations were removed from them, i.e. the suppressor cell could not be removed with Degalan beads, coated with anti-allotype antibody, but not with beads, coated with F(ab')2 fragments of the antibody; 2) help for T cells, in their response to Con A, was augmented when T cells were eliminated from the regulating adherent cell preparation. Thus, the response of spleen T cells to Con A is regulated by two adherent cells, a B helper cell and a T suppressor cell. We have previously shown that the response to phytohemagglutinin (PHA) is regulated by an adherent helper cell (4). We have found no evidence, in the present study for an adherent suppressor cell which participates in the T cell response to PHA.