Fig. 1

Serum and synovial fluid (SF) concentration levels of tryptase, chymase, and histamine and the expression of c-kit, FcεRI, tryptase, and chymase in the synovial tissues of rheumatoid arthritis (RA) patients. a The serum concentration of tryptase, chymase, and histamine in RA patients and healthy controls was measured using ELISA. b The associations between serum concentration levels of tryptase, chymase, and histamine in RA patients were analyzed using Pearson’s correlation test. c The SF concentration of tryptase, chymase, and histamine in patients with RA and osteoarthritis was measured using ELISA. d The associations between SF concentration levels of tryptase, chymase, and histamine in RA patients were analyzed using Pearson’s correlation test. Data are presented as mean ± SEM. *p < 0.05, **p < 0.01, and ***p < 0.001. e Synovial tissues of patients with RA and osteoarthritis (OA) were labeled with anti-c-kit (red), anti-FcεRI (white), and anti-tryptase (green) antibodies and photographed under appropriate filters (original magnification = × 200, scale bar = 50 μm). f Synovial tissues of patients with RA and OA were labeled with anti-c-kit (red), anti-tryptase (green), and anti-chymase (white) antibodies and photographed under appropriate filters (original magnification = × 400, scale bar = 20 μm). g Synovial tissues of patients with RA and OA were labeled with anti-FcεRI (red), anti-tryptase (green), and anti-chymase (white) antibodies and photographed under appropriate filters (original magnification = × 400, scale bar = 20 μm). Merged image shows co-localization of the three markers (yellow). Sections were counterstained with DAPI (blue). Figures are representatives of three independent experiments. RA, rheumatoid arthritis; HC, healthy control; OA, osteoarthritis