Oncogenicity of Immune Lymphoid Cells from MSV-M Regressors

Abstract

Lymphoid cells obtained from spleen and lymphnodes of mice in which the sarcoma induced by the Murine Sarcoma Virus-Moloney (MSV-M) has regressed (MSV-M regressors) inhibit MSV-M oncogenesis and induce MSV-M tumor regression in mice in which, because of immunodepressive treatments, the tumor would grow until the mice died (progressors). On the other hand, MSV-M was detected in the spleen of MSV-M infected mice, immediately after the infection or later on both in regressors and progressors. These data suggest that immune lymphoid cells from MSV-M regressors carry MSV-M. Immune lymphoid cells harvested 24 days after the infection from BALB/c MSV-M regressors were therefore injected i.p. into syngeneic mice. In three separate experiments, 26/33 injected mice died (from 40 to 102 days after the injection); tumors were present in 92 % of the examined mice. These tumors were found in various sites, and were histologically similar to the MSV-M induced rhabdomyosarcoma. Sarcoma virus was recovered from immune lymphoid cell extracts, and from the tumors induced in vivo by immune lymphoid cells. The virus isolated is capable of inducing sarcomas in mice and foci of cell transformation on mouse embryo cell cultures.