Objective To assess the effects of occupational nickel exposure on lymphocyte subsets in peripheral blood of workers.
Methods A total of 70 nickel exposed workers (exposed group) and 126 unexposed workers (control group) were recruited. Patch test with nickel sulfate was performed to distinguish a patch-negative subgroup and a patch-positive subgroup from the exposed group. The level of nickel in workplace air was measured by flame atomic absorption spectrometry, skin nickel by in ductively coupled plasma mass spectrometry, urinary nickel by dimethylglyoxime spectrophotometry, venous blood samples with EDTA anticoagulant by routine blood test, and lymphocyte subsets in peripheral blood by flow cytometry, and combined with the latter two to obtain the absolute value of lymphocyte subsets. The t-test was used to compare the differences of lymphocyte subset count between the exposed group and the control group and between the patch-negative group and the patch-positive group. The Pearson correlation was used to analyze the correlations of lymphocyte subset count in peripheral blood with urinary nickel level and length of exposure, and the general linear model was used to analyze the interaction between smoking and exposure.
Results In the exposed group, there were 14 positive spots and the positive rate was 20%. The urinary nickel levelM(P25, P75) was higher in the exposed group than in the control group13.60 (7.35, 28.76) vs 6.02 (3.93, 10.97) μg/L, P=0.000. The leukocyte, neutrophil, and value of CD4+/CD8+ in peripheral blood were higher than the control group(7.03±1.67)×109/L vs (6.23±1.35)×109/L, (4.54±1.45)×109/L vs (3.71±1.07)×109/L, (1.68±0.72) vs (1.27±0.43), respectively, Ps < 0.05, while the CD8+T cells, NK cells, and platelets were lower than those of the control group(0.52±0.26)×109/L vs (0.60±0.22)×109/L, (0.34±0.18)×109/L vs (0.45±0.25)×109/L, (200.66±69.01)×109/L vs (229.85±51.48)×109/L, respectively, Ps < 0.05. There was a positive correlation between the CD4+/CD8+ and urinary nickel levels in the total workers (r=0.152, P=0.037), but no correlation between le ngth of exposure and lymphocyte subsets in peripheral blood (P > 0.05).
Conclusion Occupational nickel exposure could cause higher CD4+/CD8+ and lower CD8+T and NK cell in peripheral blood of workers.
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