Aggregation of MHC class I molecules on a CD8+ alphabeta T cell clone specifically inhibits non-antigen-specific lysis of target cells

MHC class I molecules are target molecules recognized by TCR or NK receptors encoded in the NK gene cluster or leukocyte receptor cluster. We show that aggregation of MHC class I molecules by specific monoclonal antibodies on cytotoxic T cells, inhibits the anti-CD94 redirected lysis of P815. This inhibition is not the consequence of apoptosis or anergy of the cytotoxic T lymphocytes. In contrast, aggregation of MHC class I molecules does not inhibit either the anti-CD3 redirected cytotoxicity or the CD94-triggered up-regulation of CD25 molecules of the same T cell clone. MHC class I ligand molecules expressed by antigen presenting cells and/or T lymphocytes could therefore be able to modulate nonspecific cytotoxicity upon interaction with MHC class I molecules expressed by effector cytotoxic T lymphocytes.