The immunodominant component of a
formalinized extracellular antigen (fECA)
vaccine prepared from B16 F10
melanoma cells is the
melanoma-associated
antigen B700. We now demonstrate that a single prophylactic intrasplenic inoculation of B700
antigen (1-10 mu g) stimulates the production of
antibodies which have antiproliferative effects on B16 F10
melanoma cells in vitro. In addition, potential cytotoxic effects of splenocytes from B700
antigen inoculated mice were evaluated for two cellular immune effector functions, natural killer (NK) cell activity and lymphokine activated killer (LAK) cell activity; both activities were increased following B700
antigen inoculation. Intrasplenic injection of B700
antigen elicited an increase in the expression of the CD25
surface antigen (IL-2 R alpha) by T lymphocytes and up-regulated the expression of
IL-2 R alpha
mRNA. Thus both humoral and cellular cytotoxic immune responses might play roles in the decreased growth of primary
tumors in B700
antigen inoculated mice and in the higher survival rate in this group of animals.