Abstract

Mice pretreated with a single injection of nucleoprotein extracted from Ehrlich ascites tumor cells were predisposed to a shorter survival time when challenged with ascites cells than mice not so pretreated. The decrease in mean survival time varied with the amount of nucleoprotein injected and with the time after the injection in such a manner as to suggest the production of a sensitivity to the nucleoprotein. The earlier death of pretreated mice is though to be caused by a reaction between the sensitized mouse and the reintroduced antigen in the form of the ascites cell challenge. * This work was performed under Contract No. W-7405-eng-26 for the Atomic Energy Commission, and was supported in part by research grant (RG-4203) from the National Institutes of Health, Public Health Service. On sabbatical leave from the Department of Zoology, Duke University, Durham, North Carolina.