Characteristics of a T lymphocyte-enhancing Ab-specific monoclonal antibody. I. Genetic specificity and preferential enhancement of allogeneic reactions.

We recently described the production and characterization of an Ab-specific monoclonal antibody (mAb), designated K14.83-11, which specifically enhanced the alloreactivity of normal T lymphocytes, as well as highly selected Ab-specific T-cell lines and clones against the appropriate Ab molecule. In the present report, we have studied both the binding specificity and immunoenhancing activity of K14.83-11 in a number of genetic combinations to better characterize the possible modes through which this mAb achieves its T cell-enhancing activity. Results reported here (1) confirm and extend previous findings revealing the possible importance of the immunoglobulin G3 isotype of K14.83-11 in its immunoenhancing activity, and (2) show a distinction in the determinant binding and subsequent ability to elicit an enhancing effect. Surprisingly, K14.83-11 proved ineffective in enhancing autologous or Ab-restricted reactions. This system, then, may provide the means of comparing the functional importance of Ab expression in self-restricted and allogeneic reactions.