Selective mobilization of specifically cytotoxic T-lymphocytes at sites of inflammation in relation to BCG-induced resistance to implants of syngeneic sarcoma in mice.

The heightened and long-persisting resistance of BCG--immunized C57BL/6 mice (10-week-old males and females) to challenge with syngeneic sarcoma cells was largely restricted to the site of inoculation of the BCG. The specific cytotoxicity of peritoneal T-cells and the total number of T-cells that could be recovered from the peritoneal cavity were more than ten times greater in mice that had received BCG ip 2-4 weeks prior to inoculation of tumor than in non-BCG-treated mice. The specific T-cell-mediated cytotoxic potential of the peritoneal exudate of mice immunized with tumor was therefore at least 100 times greater in mice that had received BCG ip. This effect was detectable by 3 days after inoculation of BCG and reached a maximum 2-4 weeks later. The protection against tumor offered by pretreatment with BCG could be explained by the selective recruitment of committed T-lymphocytes to sites of chronic inflammation. The induction of nonspecifically cytotoxic macrophages and systemic changes such as generalized stimulation of the reticuloendothelial system were not contributing factors.