Incubation of 3,4-benzo(s)pyrene with serum fractions: effect on tumor production.

The effect on tumor formation in Swiss mice of incubation of 3,4-Benzo(a)pyrene [B(a)P]either with saline or saline containing serum, gamma-globulin or albumin (form mouse or rabbit) was investigated. A high incidence of sarcomas (80--100%) was obtained in Swiss mice by B(A)P incubated in vitro with rabbit serum, rabbit gamma-globulin, mouse serum, mouse gamma-globulin, and saline. A lower incidence (60--65%) was obtained with B(a)P incubated with mouse serum, mouse albumin, and rabbit albumin. The data suggest that binding of B(a)P to protein, particularly to albumin, significantly decreases the biological activity of B(a)P.