Immune response to Rauscher virus-induced leukemia in DBA mice. II. Correlation between antigenic expression and pathogenesis.

Previous studies have demonstrated that the Rauscher virus induces a biphasic erythroleukemia in DBA mice, and the regression of the disease is connected with the appearance of antibody-dependent cellular cytotoxicity. In the present work, attempts were made to reveal the mechanism leading to the lethal exacerbation of the leukemia. In the sera of leukemic mice soluble tumor-specific antigen could be demonstrated in the stages of early progression and regression but not in the stage of exacerbation. The antigen was present in form of immune complexes with free antibodies in excess. The emergence of a new population of leukemia cells has been observed during the stage of regression. On the surface of these cells the antigen receptor sites were masked by sialic acid which resulted in the loss of immunosensitivity and immunogenicity.