Abstract: Objective To investigate the effect of traditional Chinese medicine Xuezhikang on experimental autoimmune neuritis (EAN) rats. Methods EAN model was established by immunization of Lewis rats with P0 peptide 180-199. Fifteen rats were randomly divided into three groups(n=5 in each group), i.e., control group, low-dose group and high-dose group, in which Xuezhikang was administrated orally by gavage daily at a dose of 200 mg/(kg·d) and 1 000 mg/(kg·d). The levels of intracellular cytokines TNF-α, IFN-γ, IL-10 and IL-17 as well as Treg cells among MNCs and CD4⁺ T cells from lymph nodes were analyzed by flow cytometry. Results Compared with control group, Xuezhikang treatment at both high and low dose successfully ameliorated EAN on day 16 post immunization(the peak of clinical symptoms). Xuezhikang, at doses of 1 000 and 200 mg/(kg·d), inhibited the secretion of TNF-α (P<0.01), as well as IL-10 (P<0.001 and P< 0.01). Lower IL-17 level was found in high-dose group compared with that in control group (P<0.01). Compared with control group, the percentage of CD4⁺CD25⁺ T cells among lymph node mononuclear cells in low-dose group, as well as the percentages of CD4⁺CD25⁺ T cells and CD4⁺Foxp3⁺ T cells among lymph node mononuclear cells and CD4⁺ T cells in high-dose group all decreased obviously(P<0.05). The percentages of CD4⁺CD25⁺ Foxp3⁺ T cells among lymph node mononuclear cells and CD4⁺ T cells in high-dose group were lower than those in control group(P=0.075 and 0.066). Conclusion Xuezhikang can ameliorate EAN bydown-regulating the production of cytokines TNF-α, IL-10 and IL-17, but at the same time it suppresses the differentiation of CD4⁺T cells to Treg cells.

Key words: Cytokine, T regulatory cell, Xuezhikang, syndrome, Experimental autoimmune neuritis, Guillain-Barré