Characterization of the F9 antigen(s) isolated from teratocarcinoma cell culture medium.

Anti-F9 is a syngeneic antiserum directed against mouse teratocarcinoma cells which also reacts, by complement-mediated cytotoxicity, with early mouse embryos and male germ cells. A molecule (or molecules) which specifically inhibits anti-F9, cytotoxicity can be recovered from the culture medium of undifferentiated teratocarcinoma cells. The inhibitory component is not present in the culture medium of differentiated teratocarcinoma cells or embryonic fibroblasts. The inhibitory material binds to Ricinus communis I affinity columns indicating that it contains terminal non-reducing beta-galactosyl residues. The antigenicity of the molecule does not require protein, since the inhibitory activity is completely protease-resistant. Gel filtration indicates that the protease digested inhibitory material has a molecular weight of more than 80,000.