HUMAN LYMPHOCYTE CYTOCHROME-P450 2E1, A PUTATIVE MARKER FOR ALCOHOL-MEDIATED CHANGES IN HEPATIC CHLORZOXAZONE ACTIVITY

Cytochrome P450 (CYP) 2E1 is implicated in a variety of chemically ini tiated hepatotoxicities, including alcoholic liver disease, These path ological conditions arise from increased production of reactive interm ediates caused by elevated enzyme concentrations, Thus, the ability to detect enhanced CYP2E1 levels would aid in identifying individuals at high risk for. xenobiotic-promoted liver injury, With this in mind, t he present investigation assessed in vivo chlorzoxazone metabolism and compared pharmacokinetic parameters with CYP2E1 expression in blood. Twenty-two subjects were recruited and divided into two groups, contro l subjects and alcohol abusers, based on responses to two screening qu estionnaires. Those individuals with higher survey scores, i.e. those who consumed alcohol more frequently, exhibited higher rates of chlorz oxazone metabolism, Indeed, a correlation (r = 0.66, p < 0.01) was obt ained when scores were compared with the pharmacokinetic parameter AUC for chlorzoxazone. Lymphocyte microsomes isolated from blood samples obtained from these same individuals were subjected to immunoblot anal yses to detect CYP2E1 levels, That lymphocytes contained CYP2E1 was co nfirmed by reverse transcription-polymerase chain reaction and sequenc e analysis of the cDNA, Quantification of immunoreactive bands reveale d that levels of this P450 were 2.3-fold higher in alcoholics than in control subjects, This increase in lymphocyte CYP2E1 content in alcoho lic subjects coincided with a 2.1-fold increase in chlorzoxazone clear ance and a P-fold decrease in the AUC for chlorzoxazone. Importantly, a correlation (r = 0.62, p < 0.01) was observed between CYP2E1 content in lymphocytes and chlorzoxazone clearance rates, Thus, monitoring ly mphocyte CYP2E1 expression may provide a substitute for estimating hep atic activity of this P450.