IL-6 (A), IL-8 (B), VEGF (C) and TSP-1 (D) production by primary N/R and I SC. SC were isolated from N/R and I synovial biopsies as described in Materials and methods. Cells were cultivated for five days and the production of proteins was measured in conditioned culture supernatants by ELISA. Productions were normalized to DNA content. Results are expressed as the percent of the production of N/R SC. Results are expressed as mean ± SEM of 10 independent experiments performed with synovial cells isolated from 10 different donors. Comparison of mean values was performed by Mann-Whitney non-parametric analysis. *** P < 0.001: production of I SC cells was significantly different than production of N/R SC.