Pentazocine and its related compounds were examined for their effect on the cytotoxicity of
cortisone-resistant lymphocytes (CR lymphocytes) against Ehrlich
carcinoma cells. The following compounds were used:
pentazocine,
naloxone,
levallorphan,
eptazocine and
morphine. CR lymphocytes were obtained from the thymus or spleens of mice injected i.p. with
hydrocortisone acetate (125 mg/kg) 2 days before harvesting the lymphocytes. The mixture of
tumor cells and CR lymphocytes was inoculated s.c. into mice after incubation in the presence or absence of 10 microM drugs. Five weeks after inoculation, the percentage of mice developing a solid
tumor among the recipients given the
pentazocine-treated cell mixture of
tumor cells and thymic CR lymphocytes was significantly smaller than the percentage in recipients given the cell mixture treated with or without other drugs (percent
tumor takes: 21% and about 80%, respectively). Splenic CR lymphocytes did not show any cytotoxic effect, irrespective of the
drug treatment. The pretreatment of CR lymphocytes or Ehrlich cells with 10 microM
pentazocine did not affect the cytotoxicity of thymic and splenic CR lymphocytes. The proportion of the lymphocyte-conjugated
tumor cells was significantly increased when the mixture of CR lymphocytes and
tumor cells was incubated in the presence of
pentazocine. The present results indicate that the cytotoxicity of thymic CR lymphocytes is enhanced by
pentazocine possibly through the increase in the proportion of the lymphocyte-conjugated
tumor cells but enhanced not by the other drugs.