Induction of interleukin-2, natural killer cell activity and anti-melanoma antibodies resulting from immunization of mice with formalinized extracellular antigens (FECA) of murine melanoma.

Extracellular products from melanoma cells may play an important role in the pathogenesis of metastatic melanoma. Studies were designed to evaluate the effect of vaccination with formalinized extracellular antigens (FECA) of murine melanoma cells (MMM B16-F10) on survival and immune response of C57BL/6 mice. The cellular immune response was evaluated by assessing interleukin-2 (IL-2) production and natural killer cell activity, whereas the humoral immune response was examined by measuring the production of specific antibodies to extracellular antigens (ECA). IL-2 production by the splenocytes from immunized animals was significantly higher (4.7 U/ml and 3.7 U/ml) than that of controls (1.38 U/ml). The splenocytes from immunized mice revealed significantly higher natural killer cell activity. Similarly, immunized animals responded by producing specific antibodies against the extracellular melanoma antigens as detected by ELISA. The peak production of antibodies against ECA was observed on the 21st day post-immunization. These results suggest that FECA are immunogenic and may enhance active cellular and humoral anti-melanoma immunity.