Immunity to Transplantable Tumors Following Viral Oncolysis

Abstract

Summary: The intraperitoneal LD50 of an Ehrlich ascites tumor (EA) for inbred A2G mice was close to 10 cells per mouse. Mice which had been inoculated with 106 EA cells and 6 days later with WSA influenza virus underwent oncolysis and were subsequently resistant to challenge with 106 to 107 EA cells (postoncolytic immunity). This resistance could be transferred to normal A2G mice with 5 × 106 to 5 × 107 spleen cells (adoptive transfer) or with plasma, serum or ascitic fluid from immune mice. Postoncolytic EA immune sera from A2G mice were protective only when tested in A2G mice and not when tested in ICR mice. Sera which were protective in vivo agglutinated EA cells in vitro. Upon fractionation of hyperimmune serum by sucrose gradient ultracentrifugation or by column electrophoresis the agglutinin titer in vitro of the various fractions paralleled their protective power in vivo; both seemed to be associated with 7 S γ-globulin.