Fig. 1.

Hydroxychloroquine (HCQ) increases the apoptosis of synovial fibroblasts from rheumatoid arthritis (RA) patients. Fibroblast-like synoviocytes (FLS) were cultured with 1–100 µM of HCQ in duplicate. The cells undergoing apoptosis were assessed by cellular DNA fragmentation enzyme-linked immunosorbent assay (ELISA). (a) Time-dependent increase in the apoptosis of FLS treated with 100 µM of HCQ. (b) Dose-dependent increase in the apoptosis of FLS cultured with 1–100 µM of HCQ for 12 h. Data are expressed as the mean ± s.d. of six independent experiments. *P < 0·05; **P < 0·01 versus the untreated cells. (c) Phase-contrast microscopy of FLS apoptosis induced by a treatment with HCQ. RA synovial fibroblasts were cultured with 10 or 100 µM of HCQ for 12 h, and the cytolytic activity was observed under phase-contrast microscopy.