Characterization of human plasma growth inhibitory activity on serum-free mouse embryo cells

Serum-free mouse embryo (SFME) cells are a cell line derived in medium in which serum is replaced with growth factors and other supplements. These cells display unusual properties: a) they do not lose proliferative potential or show gross chromosomal aberration upon extended culture, b) they depend on epidermal growth factor (EGF) for survival, and c) they are reversibly growth inhibited by plasma and serum. Transfection of SFME cells with oncogenes (ras, neu, SV40 T antigen) results in cells that grow in serum-supplemented medium and no longer require EGF for survival. The growth inhibitory activity of human plasma on SFME cells was investigated. The activity was present in delipidated plasma and was not dialyzable against 1M acetic acid. The activity precipitated in 33% methanol, bound to concanavalin A-agarose and was retarded by Sephadex G-50 in 200 mM acetic acid. A fifty- to one-hundred-fold purification was achieved, although most of the differential inhibition of untransformed vs. transformed cells was lost in the course of the purification.