Regulation of clonal growth by anti-T-cell receptor antibody-directed lysis.

CD4 and CD8 T-cell clones were generated using the Mx9 monoclonal antibody (mAb), which recognizes the V beta 8 T-cell receptor (TcR) gene family. The interaction of these clones with the Mx9 antibody was analysed and all were found to be specifically stimulated to proliferate by plastic-adherent Mx9. In the presence of Mx9 or its F(ab')2 fragment, CD8+ Mx9+ clones were capable of specifically lysing the CD4+ Mx9+ T-cell clones. No lysis was seen of Mx9- T cells, or in the absence of the antibody. Conversely CD4+ Mx9+ T cells did not have lytic function. These results indicate that cross-linking of T cells via their antigen-specific receptors may initiate a unidirectional killing. Unlike previously reported lytic systems involving anti-TcR antibodies (e.g. anti-CD3), these results suggest that this mechanism may have an important physiological role in immune regulation. Anti-idiotypic antibodies have been shown to recognize T-cell receptors. These may exert profound immunosuppressive effects by inducing the lysis of the helper cells or B cells.