Characterization of metastasis-associated antigens on RAW117 lymphosarcoma cell lines

Abstract

A syngeneic murine model system was used to study the immunobiology of metastasis. The highly malignant RAW117-H10 cell line was compared to the less malignant parental RAW117-P cell line from which it was derived, for expression of cell surface antigens. Using rabbit antisera, two major glycoprotein antigens were detected on the tumor cell surfaces. Antigen-I was uniformly distributed over the surface of these cells whereas antigen-II had a patchy, punctate distribution. Antigen-I was displayed less on RAW117-H10 cells than on RAW117-P cells, while the expression of the other serologically distinct antigen (antigen-II) was increased on RAW117-H10 cells compared to the less malignant parental (RAW117-P) cells. This differential antigen expression was assessed by immunodiffusion, a 125I-labeled protein-A binding assay, flow cytometry and rocket immunoelectrophoresis. Both these antigens had a molecular weight of 70,000 daltons. Antigen-I bound the lectin concanavalin-A whereas antigen-II did not, suggesting that antigen-I might be the viral envelope glycoprotein gp70. The identity of antigen-II is presently unknown. Syngeneic Balb/c mice injected with highly malignant and metastatic RAW117-H10 cells coated with antiserum to antigen-I were protected from early death; this effect was not seen with RAW117-H10 cells coated with antiserum to antigen-II. The opsonizing qualities of these antisera may be different due to antibody to antigen-II being shed more rapidly than antibody to antigen-I.