The effect of tumor size on concomitant tumor immunity.

Abstract

Summary A methylcholanthrene-induced fibrosarcoma (S-10) in inbred C57BL/6 mice was used to study the effect of tumor size on the development and persistence of concomitant tumor immunity in tumor-bearing animals. S-10 tumor-bearing mice rejected a second S-10 tumor isograft that was inoculated 14 days after the initial S-10 tumor transplantation. An antigenically distinct S-11 tumor isograft grew progressively, however, indicating that concomitant tumor immunity was tumor specific. S-10 tumor-bearing mice were sacrificed 7, 21, 28, 35, or 49 days after each was given an inoculation of 105 viable S-10 cells in the right hind limb. The corresponding ratios of mean tumor weight to total body weight (TW:TBW) of the tumor-bearing mice were 0, 6, 14, 18, and 23%, respectively. Viable spleen cells from these tumor-bearing animals were injected i.p. into untreated syngeneic mice that were challenged with 103 S-10 cells 14 days after spleen cell transfer. Controls received tumor cells alone or tumor cells plus spleen cells from normal syngeneic mice. Recipients of spleen cells from mice with TW:TBW of 6 to 18% demonstrated a significantly decreased incidence of tumor development (p