Immunological Studies of Hunting Syndrome in Rats Inoculated with Friend Virus

While rats given neonatal injections of high doses of Friend virus grew up as apparently normal rats (Friend virus-tolerant rats), most rats given low neonatal doses of Friend virus died from the development of the runting syndrome (runted rats). At the transplantation of Friend virus-induced tumor (WFT-3), all tolerant rats died from the growth of the WFT-3 cells, while some of the rats that had escaped the runting syndrome rejected the WFT-3 transplants. The cytotoxic antibody to Friend virus-specific cell surface antigen was not detectable in the Friend virus-tolerant rats but was detected in all the runted rats. The titer of the antibody detected reached its highest level from 7 to 10 days before the death of the runted rats. The runting syndrome was induced by the transfer of syngeneic immune or normal lymphoid cells and also by the transfer of runted lymphoid cells into the Friend virustolerant rats. The appearance of Friend virus-specific trans plantation antigen in rats infected with Friend virus was proved by the method of local graft-versws-host reaction. These experiments demonstrate that the pathogenesis of the runting syndrome induced in rats by Friend virus consists of continuous reactions between the cells that have acquired Friend virus-specific transplantation antigen and the immunologically competent cells of the host.