Studies on Specific Transplantation Resistance to Polyoma-Virus-Induced Tumors. II. Mechanism of Resistance Induced by Polyoma Virus Infection<xref ref-type="fn" rid="FN2">2</xref>

Abstract

Polyoma-virus-induced transplantation resistance to polyoma tumors developed rapidly after virus infection: A complete inhibition of outgrowth of two different tumors was demonstrated even after infection 4 to 15 days subsequent to cell inoculation. The immunological nature of the resistance was clearly demonstrated. Total-body X irradiation with 400 r 1 day before virus infection caused a marked delay in transplantation resistance, while the same irradiation 4 to 5 days after infection had almost no effect. The appearance of antiviral antibodies in the serum of irradiated animals was also somewhat delayed, but high antibody titers were found long before transplantation resistance, which indicated that the antiviral immune response per se cannot explain the transplantation resistance effect. In neutralization experiments involving the admixture of lymphoid cells or serum and complement to polyoma tumor cells, lymphoid cells from donors infected with polyoma virus or pretreated with non-virus-releasing polyoma tumor cells inhibited the growth of the admixed polyoma tumor cells. Serum from polyoma-infected donors caused a more irregular and weaker inhibition. The inhibition brought about by the lymphoid cells was clearly distinguished from, a resistance effect induced by an accidental virus infection because of its demonstration in animals having no antiviral antibodies in their sera.