Up and down regulation of serine esterase release from mouse cytotoxic T lymphocytes by tumor-promoting phorbol ester

Activation of mouse cytotoxic T lymphocytes (CTL) with target cells expressing antigen resulted in the release of serine esterase (SE) into the culture supernatant. Short term treatment (3 hr) of CTL with phorbol-12-myristate-13-acetate (PMA) plus ionophore also caused stimulation of SE release from CTL, while neither PMA alone or ionophore alone could induce SE release. In contrast to this, long term treatment (24 hrs) of CTL with PMA resulted in the inability of CTL to release SE in respond to antigen or PMA plus ionophore. It was also demonstrated that protein kinase C activity of CTL disappeared during induction of desensitization of CTL by PMA.