Activation of resting T lymphocytes by a monoclonal antibody directed against an allotypic determinant on the T cell receptor.

The murine monoclonal antibody F23.1 reacts with an allotypic determinant on the beta chain of the T cell receptor expressed by approximately 20% of T helper and cytotoxic T lymphocytes of most common mouse strains. This IgG2a antibody, either in soluble form or covalently coupled to Sepharose beads, can activate resting T cells from naive animals to proliferate. Interestingly, under all conditions of activation, the antibody can only induce proliferation if exogenous lymphokines in the form of Con A supernatant are provided. Thus, it is unlike most lectins and anti-T3 antibodies in this regard. Furthermore, under all conditions of culture, F23.1 activates preferentially the Lyt-2+ subset of T cells. This is the case even in the presence of accessory cells. Further evidence is provided that two soluble lymphokines, different from IL2, are required to initiate IL2-dependent growth and to allow the expression of lytic activity.