[Effects of occupational lead exposure on the indicators of immune function of workers]

Objective: To investigatethe effects of different blood lead levels on indicators of immune function in occupationally lead-exposed populations. Methods: From October to December 2023, a total of 126 occupationally exposed lead workers of a company in Guizhou Province were selected, and their basic information was collected through questionnaires. Inductively coupled plasma mass spectrometry was used to detect blood lead levels in the study population. Workers were categorized into Group 1, Group 2 and Group 3 based on blood lead levels (blood lead levels <200 μg/L, 200~400 μg/L and >400 μg/L). Lymphocyte subpopulation marker leukocyte differentiation antigen (CD) in peripheral blood and interleukin (IL) -1β, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12p70, IL-17, tumor necrosis factor-alpha (TNF-α), and interferon (IFN) -γ in serum were examined by flow cytometry. Serum levels of immunoglobulin (Ig) A, IgG, IgM, and complement proteins (C3, C4) were measured by immunoscattering turbidimetry. Data were statistically analyzed using rank sum test, Chi-square test or Fisher exact probability method for multiple samples. Results: Compared with group 1, the percentage of CD3(+)CD8(+) and CD4(+)CD25(+) cells decreased (P<0.05) and the percentage of CD4(+) CD95(+) cells increased in the lead-exposed populations in groups 2 and 3 (P<0.05) ; however, the serum IL-1β, IL-2, IL- 5, IL-8, IL-12p70, and IFN-γ levels were decreased (P<0.05) in group 3. Meanwhile, IgG (P<0.05) and IgM levels in serum of lead-exposed population in group 2 and group 3 were reduced (P<0.05) comparing with group 1. Spearman correlation analysis showed that blood lead levels of workers were negatively correlated with the percentage of peripheral blood CD8(+)CD95(+) cells, CD3(+)CD8(+) cells, CD3(-)CD16(+) CD56(+) cells, IgG, IgM, and IgA (r(s)=-0.20, -0.22, -0.23, -0.24, -0.26, -0.35, P<0.05), but was positively correlated with the level of CD3(+)CD4(+) cells (r(s)= 0.18, P<0.05). Regression analysis revealed that blood lead level was a risk factor for the percentage of CD8(+)CD95(+) cells, CD3(+)CD8(+) cells, CD3(-)CD16(+) CD56(+) cells, IgG, IgM, and IgA (P<0.05) . Conclusion: Different lead loads can lead to abnormal changes in peripheral blood lymphocyte subsets, cytokines, and immunoglobulin levels in occupationally lead-exposed people. Lead exposure in occupationally lead-exposed populations may affect their immune function.