In the micro-leukocyte adherence inhibition (LAI) assay, crude membrane preparations of murine colon adenocarcinoma and of melanoma (B16) are specifically recognized only by peritoneal cells from syngeneic mice bearing a small-to-moderate burden of the respective tumor. Three extraction procedures were performed on the membrane preparations of the 2 tumors: 1 m perchloric acid (PCA), 3 m KCI, and deoxycholate solubilization followed by brief papain treatment. The deoxycholate:papain extract was without activity in the LAI assay; however, significant recognition of the former 2 extracts was observed with peritoneal cells from tumor-bearing mice. Plasma membrane vesicles were prepared from cultured tumor cells and also demonstrated specific antigenic activity.

The PCA extract of MCA-38 tumor was fractionated on Bio-gel P-200 and on Sephacryl S-200, and the LAI reactivity was found in a fraction with a molecular weight greater than 160,000. A rabbit antiserum to the 1 m PCA extract of MCA-38 tumor was prepared, and after solid state absorption with 1 m PCA extracts of C57BL/6J murine colon, liver, and kidney, no Ouchterlony immunoprecipitation activity was observed against the P-200 fraction containing the LAI reactivity. Immunoprecipitation was obtained with the PCA fraction with a molecular weight of 45,000 to 158,000. This material is heat stable and migrated as a β-protein in immunoelectrophoresis. These results suggest that the MCA-38 colon carcinoma contains a glycoprotein with some CEA-like properties, as well as a distinct specific tumor-associated antigen recognized in the LAI assay.

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Presented at the International Workshop on Leukocyte Adherence Inhibition, May 15 to 17, 1978, Buffalo, N. Y. This work was supported by USPHS Grant CA 23646 from the Department of Surgical Oncology, Roswell Park Memorial Institute, 666 Elm Street, Buffalo, N. Y. 14263.

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©1979 American Association for Cancer Research.