Conditions favoring immunological enhancement of a murine allogeneic lymphoma.

An in vivo model was used which permits the growth of AKR lymphoma allografts inoculated within a glass cylinder subcutaneously implanted in BALB mice. Pretreatment of the host with acellular tumor extracts or tumor cells enclosed within a diffusion chamber significantly increased tumor incidence. On the contrary, donor spleen extracts did not alter tumor incidence while viable spleen cells within a diffusion chamber even prevented tumor development. It can be concluded that in this model a condition of maximal tumor enhancement can be attained with soluble tumor antigen but not with normal spleen extracts.