Binding of benzo[a]pyrene and intracellular transport of a bound electrophilic benzo[a]pyrene metabolite by lipoproteins.

Human serum lipoproteins were isolated by means of size exclusion h.p.l.c. Non-covalent uptake of [3H]benzo[a]pyrene was quantitated for fractions collected from the effluent of a liquid chromatographic separation of human serum, and was found to directly correlate with the lipoprotein concentration. An electrophilic benzo[a]pyrene metabolite, [3H]trans 7,8-dihydrodiol-9,10-epoxybenzo[a]pyrene, non-covalently associated with low density lipoproteins was transferred to human lymphocytes in vitro and bound acid-precipitable nucleic acids of the lymphocytes as a function of time. Benzo[a]pyrene metabolite binding to lymphocyte DNA was demonstrated by means of CsCl density gradient analysis. Non-mitogen-stimulated lymphocytes exposed to very low concentrations of carcinogen in the presence of low density lipoprotein demonstrated [3H]thymidine incorporation; without the concomitant addition of low density lipoprotein the low concentrations of carcinogen did not stimulate [3H]thymidine incorporation.