CLASSIFICATION OF MUTATIONS AT THE HUMAN HPRT-LOCUS IN T-LYMPHOCYTES OF BUS MAINTENANCE WORKERS BY MULTIPLEX-PCR AND REVERSE TRANSCRIPTASE-PCR ANALYSIS

Polymerase chain reaction (PCR)-based screening methods were used to c lassify mutations arising in vivo at the hypoxanthine guanine phosphor ibosyl-transferase (hprt) locus in small samples of human T-lymphocyte clones (<5x10(4) cells) from 29 bus maintenance workers exposed to di esel exhaust, and 14 control individuals, All subjects were healthy, n on-smoking males, Among 462 T-cell mutants studied by multiplex-PCR of genomic DNA, only 12 (2.6%) deletions were found: three total deletio ns, five partial exon deletions and four mutants with one or two exons deleted, Point mutations were classified in 323 mutants using reverse tanscriptase-PCR amplification: 74 (22.9%) of these had splice site m utations and 241 (74.6%) had coding errors. Splice mutation was more f requent among the garage workers (24.8%) as compared to the controls ( 19.5%), possibly reflecting a polycyclic aromatic hydrocarbon-specific mutation induction in these workers, Our results also show that both gene deletion and splice mutation at We hprt-locus in T-cells of healt hy non-smokers could be less frequent than previously reported.