Effect of Splenectomy on the Regression of Transplantable Tumors¹

Splenectomy of adults increased the incidence of spontaneous regression of Sarcoma 180 in Swiss HaICR mice and that of the subline S-180/B₆ in AKR, but not in C3Hf/HeHa or C57BL/6Ja mice. The incidence of regression of Ehrlich carcinoma was increased, as a consequence of splenectomy, in Swiss HaICR mice in which Sarcoma 180 had previously regressed twice, but not in those in which this tumor had regressed only once.

The incidence of regression of Sarcoma 180 induced by 6-mercaptopurine and kethoxal-bis(thiosemicarbazone), but not that caused by vitamin B₆ deficiency, was markedly increased in splenectomized Swiss HaICR mice. The incidence of regression of S-180 induced by vitamin B₆ deficiency was greatly reduced by neonatal thymectomy. This reduction was less marked in mice which had been neonatally thymectomized and splenectomized.

These observations are discussed with reference to the hypothesis that selective therapeutic effects on Sarcoma 180 are dependent in part upon an alteraton of the balance between cellular immunity and humoral antibody response elicited by the tumor.