Antibody-dependent lymphocyte cytotoxicity in the murine sarcoma virus system: activity of IgM and IgG with specificity for MLV determined antigen(s).

Antisera with specificity for Moloney leukemia virus-(MLV) determined antigen(s) were studied for their ability to induce MLV antigen bearing target cell reduction by lymphocytes in microcytotoxicity assays. Sera from animals which had regressed Moloney sarcoma virus (MSV) tumors as well as sera from animals with progressively growing MSV tumors were found to induce normal lymphocytes to be active against the targets. Regressor serum was found also to induce cytotoxicity by immune lymphocytes from a tumor-bearing animal 15 days after MSV and from a regressor 50 days after MSV infection. Both the 19S and 7S Sephadex G-200 fractions of the antisera were found to induce cytotoxicity by normal lymphocytes and to potentiate the cytotoxicity of MSV immune lymphocytes. These activities were shown to be IgM and IgG, respectively, by the use of Sepharose-coupled anti-mouse IgM and anti-mouse IgG columns. All activity was removed by passing sera over both columns.