[One-year continuous observation of change in peripheral T cell subsets in workers exposed to low levels of benzene].

ABSTRACT

OBJECTIVE: To observe the T cell subsets and blood cells in the peripheral blood of workers exposed to low levels of benzene for one year, and to investigate the relationship between T cell function impairment and benzene-induced hematopoietic injury after benzene exposure. METHODS: Eighty-eight workers (58 males and 30 females, aged 18 ∼ 22 years) who just began to work in the workshop of a paint factory with exposure to benzene in Guangzhou, China were assigned to experimental group, and 88 workers (58 males and 30 females, aged 18 ∼ 25 years) who worked in the workshop without exposure to benzene were selected as controls. The blood samples of the workers were examined once every 4 months to measure the percentages of peripheral T cell subsets and peripheral blood cell counts in the one-year study. The benzene concentrations at operation points were also measured. RESULTS: The peripheral blood cell counts in the benzene-exposed workers had no significant changes in the first and second examinations; the white blood cell (WBC) counts in the experimental group in the third and fourth examinations were significantly lower than that in the control group [(6.4 ± 3.0)×10(9)/L and (6.3 ± 2.7)×10(9)/L vs (7.3 ± 3.0)×10(9)/L, P < 0.05], and the platelet (PLT) count in the experimental group in the fourth examination was also significantly lower than that in the control group[(179 ± 74)×10(9)/L vs (189 ± 70)×10(9)/L, P < 0.05]. Compared with those in the control group (CD4+ 54.29 ± 12.78%, CD8+ 37.25 ± 12.30%), the percentage of CD3+ T cells in the experimental group increased in the third examination; the percentage of CD4+ T cells in the experimental group decreased continuously in the second, third, and fourth examinations (50.77 ± 11.05%, 45.40 ± 9.41%, and 41.27 ± 10.62%), while the percentage of CD8+ T cells in the experimental group kept increasing (46.07 ± 10.18%, 50.36 ± 10.62%, and 56.40 ± 9.41%) (P < 0.05). CONCLUSION: The change in T cell subsets precedes that in the blood system in the workers exposed to low levels of benzene.