OBJECTIVETo observe the distribution of TCR V alpha gene repertoire and clonal expansion in peripheral blood mononuclear cells from 9 donors and 16 workers exposed to benzene.

METHODSComplementarity determining region 3 (CDR3) of TCR V alpha subfamily genes were amplified using RT-PCR. The PCR products were further analyzed by genescan to evaluate clonality of T cells.

RESULTSAlmost all of 29 V alpha subfamily could be detected in 9 donors. 1 approximately 11 V alpha subfamilies were identified in all but one of the workers studied. The most frequently expressed V alpha subfamily were V alpha 3, V alpha 12 and V alpha 19 (68.8%), V alpha 14 (56.3%), with a lower expression rate found in V alpha 5, V alpha 15, V alpha 16, V alpha 22, V alpha 23 and V alpha 24 (6.3%). Clonal expansion T cells in one or more V alpha subfamily were found in 12 out of all workers studied, including oligoclonal, oligoclonal trend and biclonal patterns. The frequency of clonal expansion T cells in V alpha 12, V alpha 14 and V alpha 19 subfamilies were higher than others.

CONCLUSIONSkewed distribution and clonal expansion of TCR V alpha subfamily T cells could be found in workers exposed to benzene. V alpha 12, V alpha 14 and V alpha 19 subfamilies may be highly sensitive to benzene exposed. This is the first report of clonal expansion TCR V alpha T cells in the benzene-exposed group. The bias pattern of TCR V alpha T cells may be due to the immune cytotoxicity from benzene. However, whether the oligoclonality in some V alpha subfamilies reflect the phenomenon of clone absence or may be a response clone to benzene-related impairment during exposed to benzene, remains an open question.