A comparison of the role of protein synthesis in cell-mediated cytotoxic reactions.

Pactamycin, an irreversible inhibitor of protein synthesis, was employed to investigate the requirement for protein synthesis during in vitro cell-mediated cytotoxic reactions. The cellular reactions examined included direct cell-mediated cytolysis (DCMC) of EL-4 tumor cells by alloimmune lymphocytes, antibody-dependent cell-mediated cytolysis of HEp-2 tumor cells (ADCC-T), and antibody-dependent cell-mediated cytolysis of chicken erythrocytes (CRBC) (ADCC-E). Pretreatment of alloimmune lymphocytes with pactamycin (PAC) did not alter the DCMC reactivity osf the effector cells even though protein synthesis was inhibited by >90%. Similarly, inhibition of protein synthesis followed by 6 hr of in vitro incubation prior to the assay did not significantly reduce reactivity. Pretreatment of normal lymphocytes failed to inhibit cytotoxic reactivity when employed in an ADCC assay against HEp-2 cells, but produced partial inhibition of ADCC reactivity against CRBC. Incubation following PAC treatment had no effect on ADCC-T, but abrogated all ADCC-E activity within 3 hr. The data presented indicates that the effector cells mediating ADCC-E and those mediating both ADCC-T and DCMC differ markedly in their requirements for continued protein synthesis.