Abstract

Soluble cytochrome P-450 prepared from microsomes of rat liver or from livers of chick embryos was shown to be capable of eliciting an immunological response in rabbits. The γ-globulin fraction from sera of immunized rabbits reacted with soluble P-450 of the same species. Precipitating reactions were obtained when antibody and antigen were incubated in the fluid phase, as well as by agar diffusion techniques. Lack of cross-reactivity between species was demonstrated when antibody to rat cytochrome P-450 was allowed to react with soluble P-450 from chick embryo livers and when antibody to chick cytochrome P-450 was allowed to react with soluble P-450 from rat liver. The Precipitate obtained upon reaction of antibody and antigen from the same species showed a typical CO difference spectrum with an absorption maximum at 450 nm and a type II difference spectrum with aniline. However, no type I difference spectrum could be obtained after the addition of sodium hexobarbital to the antibody-antigen complex, suggesting that the binding site of the immune complex may be at or near the type I binding site.