Reduction of pulmonary metastases of B16 melanoma by human recombinant interleukin 2 and lymphokine-activated killer cells in immunosuppressed C57BL/6 mice receiving anticancer agent.

The immunosuppressive effect of a water-soluble nitrosourea derivative, 1-(4-amino-2-methyl-5-pyrimidinyl) methyl-3-(2-chloroethyl)-3-nitrosourea (ACNU), was evaluated in terms of the cytotoxicity of spleen lymphocytes, and the restoring effect of lymphokine-activated killer (LAK) cells and/or human recombinant interleukin-2 (rIL-2) on the cytotoxicities of spleen lymphocytes was examined in ACNU-treated C57BL/6 mice. In addition, we tested whether the administration of LAK cells and/or rIL-2 could reduce the increased numbers of pulmonary metastases in ACNU-treated mice. The maximum effective dose of ACNU suppressed the cytotoxicity of spleen lymphocytes and pretreatment with ACNU enhanced the induction of artificial pulmonary metastases. The administration of LAK cells and/or human rIL-2 restored the cytotoxicity of spleen lymphocytes against YAC-1 and syngeneic B-16 melanoma cells in ACNU-treated mice, and these treatments partially suppressed the increased numbers of artificial pulmonary metastases of B-16 melanoma cells in ACNU-treated mice. These results are extremely important in providing a rationale for the introduction of adoptive immunotherapy using LAK cells and rIL-2 in patients with advanced cancer who are being treated with anticancer agent(s).