Fig. 2

CD4⁺ T cell subset frequencies in blood and synovial fluid distinguish patients with rheumatoid arthritis (RA) from patients with osteoarthritis (OA). Frequency of CD4⁺ T helper subsets (a, c) and T regulatory subsets (b, d) identified according to phenotypic markers in blood and synovial fluid from healthy donors (HD) (open diamonds), patients with OA (open circles) and patients with RA (closed circles): *p ≤ 0.05, **p ≤ 0.005, Mann-Whitney unpaired two-tailed t test. Mean value ± SEM are reported. Treg T regulatory cells, Th T helper cells