Background Paraquat (PQ) is a widely used herbicide. Current research focuses on its neurotoxicity. However, the impact of PQ on peripheral immune system is not comprehensively studied.
Objective This study aims to study the effects of PQ on peripheral immune system, especially on the number, differentiation, and activation of lymphocytes.
Methods SPF female C57BL/6 mice, 6-8 weeks old, were randomly assigned to three groups, namely control group, 2 mg/kg PQ for 1 week group, and for 2 weeks group, with 8 mice in each group. Mice were subcutaneously injected with PQ once a week. Spleen was harvested 1 or 2 weeks after exposure to measure the number of splenocytes and lymphocytes, as well as the differentiation and activation of lymphocytes by flow cytometry.
Results Compared with the control group, the number of splenocytes did not change after 1 or 2 weeks of PQ exposure (P > 0.05); the numbers of CD4+T cells and CD8+ T cells did not change either (P > 0.05); the number of B cells was higher after 2 weeks of exposure (t=-2.304, P < 0.05), but not after 1 week of exposure (P > 0.05). Compared with the control group, PQ decreased the proportions of type 1 T helper (Th1) cells (t=0.019, P < 0.05) and type 2 T helper (Th2) cells (t=0.038, P < 0.05) to CD4+T cells after 2 weeks of exposure, but not after 1 week of exposure (P > 0.05); PQ did not affect the proportions of T helper 17 (Th17) cells and regulatory T (Treg) cells (P > 0.05) to CD4+T cells. In addition, PQ reduced the expressions of a major histocompatibility complex class Ⅱ molecule I-A (t=0.047, P < 0.05) and B-cell surface antigen CD40 (t=0.000, P < 0.01) after 2 weeks of exposure, but did not affect the expression of B-cell surface antigen CD86 (P > 0.05).
Conclusion PQ exposure could increase the number of B cells, inhibit the differentiation of CD4+T cells into Th1 and Th2 cells, and inhibit the activation of B cells, suggesting that PQ could cause immune dysfunction by affecting the number, differentiation, and activation of immune cells.
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