Leukocyte adherence inhibition response to murine sarcoma virus-induced tumors. II. Requirement for T-cell subpopulations and macrophages

Extraction of immunogenic murine mammary tumor antigens with 1-butanol

Solubilized tumor associated antigens (TAA) were prepared by a single phase 1-butanol extraction of a transplantable murine mammary adenocarcinoma (H2712), other syngeneic non-mammary tumors, normal mammary tissue, and embryonic tissues. The crude butanol extract (CBE) of H2712 was found to have tumor-specific activity both in vitro in the leukocyte adherence inhibition (LAI) assay and in vivo in an immunoprophylaxis assay. The failure to detect any of the major mammary tumor virus (MTV) envelope glycoproteins or internal core protein in CBE-H2712 and the failure of tumor-bearing mice to give a LAI response to CBE prepared from embryonic tissues suggests that the CBE antigens which are responsible for LAI activity are not viral or oncofetal antigens. Enzymatic treatment of the CBE-H2712 indicated that a sialated glycoprotein formed the antigenic determinants recognized in CBE by the LAI assay. Gel filtration of LAI-reactive CBE-H2712 on a Sephadex G-75 column isolated both the in vitro and in vivo tumor-specific activity in a fraction pool. Polyacrylamide gel electrophoresis revealed the presence of a 67 kD subunit as the major species in the active fraction.