A competitive enzyme linked immunosorbent assay for the determination of N-acetyltransferase (NAT2) phenotypes.

The ratio of 5-acetylamino-6-amino-3-methyluracil (AAMU) to 1-methylxanthine (1X) in urine samples after caffeine ingestion can be used to indicate human N-acetyltransferase (NAT2) phenotypes. In previous studies, this ratio has been determined by LC or capillary electrophoresis. The possibility that this ratio could be determined by competitive antigen enzyme linked immunosorbent assays (ELISAs) has been investigated. Polyclonal antibodies were raised in rabbits against synthetic derivatives of AAMU and 1X, and competitive antigen ELISAs were developed after isolation of the IgGs by ion-exchange chromatography. The competitive antigen ELISA correctly identified previously determined NAT2 phenotypes and gave the expected distribution of slow and fast N-acetylators within a group of 48 individuals.