Objective:To explore the effects and mechanism of Huanglian Wendan decoction on experimental autoimmune neuritis（EAN）.Method:EAN model was established by immunizing Lewis rats with peripheral nerve myelin sheath antigen（P257-81）peptide and complete Freund’s adjuvant（CFA）.Lewis rats were randomly divided into Huanglian Wendan decoction high-dose group and low-dose group

the EAN model group and normal group.Huanglian Wendan decoction high-dose group and low-dose group were lavaged with 26.89 g·kg-1·d-1 or 6.79 g·kg-1·d-1 once daily from day 0 to day 15 post-immunization.The effects were assessed in terms of appearance of clinical signs

histopathology and T cells

macrophages infiltrating in sciatic nerve sections

T help 17（Th17） cells and Foxp3+ regulatory T（Foxp3+Treg） cells in peripheral blood

mRNA levels of inflammatory cytokines: tumor necrosis factor-α（TNF-α）

interferon-γ（IFN-γ）

interleukin-6（IL-6） and interleukin-17（IL-17） in the lymph nodes.Result: Huanglian Wendan decoction high-dose group primaryneurological signs were found at day 11.92±1.38

it was later than that in EAN group.The maximal neurological score（2.41±1.09） and the mean histological scores（0.58±0.51） of high-dose group were lower than that in EAN group.Huanglian Wendan decoction high-dose group and low-dose group reduced accumulation of macrophages and T cells in sciatic nerves.In peripheral blood

Foxp3+Treg cells in high-dose group and low-dose group（15.06±1.35

9.18±1.00）% were increased

but Th17 cells（1.88±0.47

2.71±0.39）%were decreased.Furthermore

TNF-α

IFN-γ

IL-6

IL-17mRNA levels in the lymph nodes of high-dose group（0.38±0.02）%

（0.45±0.08）%

（0.34±0.13）%

（0.63±0.17）%and low-dose group（0.45±0.03）%

（0.60±0.05）%

（0.74±0.12）%

（1.04±0.17）% significantly suppressed.Conclusion:Huanglian Wendan decoction could effectively suppress autoimmune response in EAN

it can treat EAN effectively.