Phorbol-ester stimulated lysis of weak and nonspecific target cells by cytotoxic T lymphocytes.

We have investigated the effects of short-term incubation of cloned and in vivo-produced cytotoxic T lymphocytes (CTL) with phorbol esters on their lytic activity against weak and nonspecific targets. These experiments demonstrate that 4 beta-phorbol-12-myristate, 13-acetate (PMA), 4 beta-phorbol-12,13-dibutyrate, and 4 beta-phorbol-12,13-didecanoate, but not the 4 alpha-phorbol-12,13 didecanoate esters stimulate the lytic apparatus. The stimulation is specific for the CTL rather than the target and appears to be nearly instantaneous in action. This rapid stimulation of the CTL lytic process is consistent with previously reported effects of phorbol esters associated with T cell activation in other functional assays.