Tumor-associated antigens of rat moloney sarcoma cells. I. Cell-surface antigens.

The dissociated cell surface membranes of a rat Moloney sarcoma (MST), derived from a BN rat, were extracted with 2 M KI, with 6 M guanidine thiocyanate, or by papain digestion. Extracts obtained with these three reagents were fractionated on columns of controlled-pore glass, 170 A pore size. A fraction was eluted from each preparation that contained tumor-associated antigens (TAA), viral, fetal, and histocompatibility antigens. With an antibody specific for TAA, the TAA, devoid of detectable viral, fetal, and histocompatibility antigens, were co-precipitated by addition of goat antibody to rat immunoglobulin. After electrophoresis, on slab gels, three bands were detected with estimated m.w. of 185,000, 150,000, and 70,000. No such bands were detected on slab gel electrophoresis with extracts of BC5, a chemically induced tumor, of normal BN lymphoid cells, of M-MuLV, or of fetuses, after incubation with anti-TAA antibody and goat antibody to rat immunoglobulin. TAA extracts prepared with 2 M KI, 6 M guanidine thiocyanate, or papain digestion showed immunologic reactivity. Cold TAA inhibited the co-precipitation of labeled TAA by rat antibody specific for TAA; they elicited antibody in guinea pigs but not in rats; and antibodies specific for TAA were cytotoxic to MST in the presence of C.