Increased immunogenicity of ehrlich ascites cells after heat treatment

Immunization of Swiss mice with Ehrlich ascites cells which had been exposed in vitro to 42.C for 3 hours is more effective, so far as subsequent tumor transplantation is concerned, than immunization with radiation-inactivated cells or with cells exposed to 42.5C for 6 hours. These results, which indicate that upon moderate heat treatment there is a definite increase of the immunogencity of these cells, may have some relevance as to the mechanism of the delayed tumor regression which is often clinically observed after hyperthermic perfusion.