Chemoimmunotherapy of MC-induced mouse sarcomas with human recombinant interleukin 2 and cyclophosphamide: age-dependent decline of the therapeutic efficacy.

Age-dependent decline of the anti-tumour efficacy of local IL-2 immunotherapy and chemoimmunotherapy utilizing human recombinant interleukin 2 and cyclophosphamide was investigated in B10 mice bearing syngeneic MC-induced sarcoma. Repeated peritumoral injections of rIL-2 substantially inhibited growth of transplantable MC-induced sarcomas in syngeneic young adult mice whereas no effect was observed in the aged mice. Chemoimmunotherapy of the MC-induced sarcomas in the young adult and in the aged mice treated with cyclophosphamide plus rIL-2 revealed that subthreshold doses of CY were capable of significantly potentiating the immunotherapeutic effect of rIL-2 in young adult mice but not in the aged mice.