Stimulation of cellular ingestion by basic proteins in vitro.

The ingestion of carbon and benzpyrene particles in vitro by rat peritoneal macrophages, baby hamster kidney fibroblasts (BHK-21) and mouse L-cells has been shown to be significantly stimulated by the inclusion of histone or polylysine in the culture medium. Parallel studies using methylated bovine albumin did not significantly stimulate carbon or benzpyrene uptake relative to untreated control cultures. Incubation of carbon particles with histone before inclusion in the culture medium of macrophages resulted in the same degree of uptake as in the cultures where carbon and histone were added independently of each other. The implications of these findings to in vivo chemical carcinogenesis are examined.