OCCURRENCE OF SOLUBLE ANTIGEN IN THE PLASMA OF MICE WITH VIRUS-INDUCED LEUKEMIA

Abstract

The plasma of mice infected with Rauscher virus contains, in addition to infective virus, a soluble antigen that has the same specificity as the cellular antigen of leukemias induced by Rauscher virus. Virus can be titrated in C57BL mice by measuring the production of cytotoxic antibody in response to the inoculation of serially diluted infective plasma. This method is as sensitive as the production of Rauscher disease in susceptible BALB/c mice. The soluble antigen is demonstrated by its capacity to adsorb onto certain cells and thus render them susceptible to lysis by specific cytotoxic Rauscher antiserum. An antigen with the same specificity appears in the plasma of mice with transplanted Rauscher leukemias of lymphatic type. The plasma of mice with primary leukemias induced by Moloney or Friend viruses similarly sensitizes indicator cells to the cytotoxic activity of the homologous typing sera, and also to Rauscher antiserum. These cross reactions provide further evidence that leukemias induced by the Friend, Moloney, and Rauscher viruses are immunologically related (FMR system). Soluble antigen has not yet been found in the plasma of mice with leukemias induced by Gross virus.