Plasma "cold-insoluble globulin" protects cytotoxic lymphocytes from ATP inhibition: 2. Immunization against viral cell surface antigen stimulates cytotoxic cells to lyse tumor cells.

The present studies examined the immunoregulatory factors that modulate T-lymphocyte cytotoxic activity against tumor cells. At 30 days postvaccination with hepatitis B virus surface antigen(s) (HBsAg), peripheral blood lymphocytes (PBL) from HBsAb-seropositive healthy donors showed 8-10-fold increase in their cytotoxic activity against human hepatocellular carcinoma PLC/PRF/5 cells. However, there was no effect against human embryonic liver or lung fibroblasts (WI-35) cells. After cloning, these cytotoxic lymphocytes responded to HBsAg, phytohemagglutinin (PHA), and neuraminidase (VCN) with significant increases in cytotoxicity. These cloned, activated PBL also had no effect on human embryonic liver or lung fibroblasts. Exogenous 5'-triphosphate (ATP) inhibited the lymphocyte cytotoxic activities. The inhibition was ATP concentration-dependent. Also, colchicine, a tubuline depolymerizing agent, inhibited effector cell cytotoxic lymphocyte activity. Colchicine binds to the target cells without causing cell lysis. Preincubation of the cytotoxic lymphocytes with "cold-insoluble globulin" (CIg) protected the cells from ATP and colchicine inhibition.