The
cortisone-resistant lymphocytes (CR lymphocytes) of mice treated with a group A streptococcus, Su strain, or Freund's complete adjuvant (FCA) were examined for their cytotoxicity on Ehrlich
carcinoma cells and sarcoma-180 cells. Female mice of the ddY strain, 7-8 weeks of age, were injected subcutaneously with streptococci or FCA in
emulsion, and they were killed 14 days later. To obtain CR lymphocytes, mice treated with and without agents were injected intraperitoneally with
hydrocortisone acetate (125 mg/kg) 2 days before killing.
Tumor cells and CR lymphocytes from thymus, spleen or mesenteric lymph node were suspended in
Hanks balanced salt solution supplemented with 2%
bovine albumin. The cytotoxicity of CR lymphocytes on
tumor cells was examined by the Winn test:
Tumor growth was observed in mice inoculated s.c. with the mixture of
tumor cells (T) and CR lymphocytes (L) at a T/L ratio of 1/10 (10(6)
tumor cells/mouse). The mesenteric and thymic CR lymphocytes of mice treated with streptococci or FCA were more effective than the corresponding lymphocytes of untreated mice in suppressing the
tumor growth in animals given the cell mixture. This suggests that the treatment of mice with streptococci or FCA results in an enhancement in the cytotoxicity of mesenteric and thymic CR lymphocytes against the
tumor cells.