Fig. 3

Effects of 5-hydroxytryptophan (5-HTP) on disease activity in the mice with collagen-induced arthritis (CIA). a Protocol for CIA induction and 5-HTP supplement. CII bovine type II collagen, CFA complete Freund’s adjuvant. b and c Arthritis scores and histological scores (mean ± standard error (SE)). d Histological staining of arthritic ankle joints. Ti tibia, Ta talus. e Serum cytokine levels (mean ± SE). f Percentages of IFNγ⁺CD4⁺ T cells (IFNγ⁺CD4⁺CD3⁺ cells/CD4⁺CD3⁺ cells, mean ± SE) in the spleen (Sp) and inguinal lymph nodes (Ln). *Significant compared with group 1. Each group contained eight mice. Multiple comparisons were performed using the Kruskal–Wallis test, if significant (p <0.05), then the Duncan test was used to find out which pairs were different