Antigen recognition by human T lymphocytes is linked to surface expression of the T3 molecular complex.

Four distinct surface molecules on human T cells are defined by the monoclonal antibodies anti-T1, anti-T3 (anti-T3A), anti-T11 and anti-T12. Following cell binding, anti-T3 (anti-T3A) and anti-T1 induce independent modulation of their respective ligands, whereas anti-T11 and anti-T12 do not. To explore the biological consequences of this modulation, we used cloned populations of T4 and T8 cytotoxic T lymphocytes. Anti-T3 (anti-T3A), but not anti-T1, inhibits cytotoxic T lymphocyte effector function by T4 and T8 clones as well as antigen-specific T cell recognition. The latter is not secondary to a generalized inhibitory effect since responsiveness to interleukin 2 is maintained. Moreover, after modulation, cytotoxic T lymphocytes recover cytolytic function in parallel with reexpression of surface T3 molecules. We provide evidence for a direct linkage between antigen recognition by T lymphocytes and surface expression of the T3 molecular complex.