Host defence mechanisms in the spontaneous regression of S-180

Abstract

Spontaneous regression of S- 180 was found in 32% of inoculated inbred Swiss mice and 26% random bred mice. Furthermore, the surviving mice became completely resistant to subsequent implantation of S- 180 and partially resistant to challenge with Ehrlich's ascites carcinoma tumors. Whole body X-radiation of the mice prior to tumor inoculation reduced the incidence of regression of S- 180 10–30%. Implantation of S- 180 into new born Swiss mice yielded 100% takes with 100% mortality. Serological studies using the passive cutaneous anaphylaxis technique of Ovary, complement fixation and tanned haemagglutination techniques demonstrated the presence of antibody against S- 180 in the serum of mice with spontaneously regressing tumors. Passive transfer of immunity to normal mice could not be achieved by intraperitoneal injection of immune serum. However, S- 180 growth in normal mice was completely inhibited by intraperitoneal injection of spleen cells from immune mice or by parabiosis with immune mice.