SF(RA) has a higher concentration of IL-6 compared to SF(OA; 7380 vs. 525.4 pg/ml; P = 0.009) and SF(control; 7380 vs. 22.4 pg/ml; P = 0.024), confirming previous reports (Kokebie et al., 2011). This evidence concerns the gene IL6 and rheumatoid arthritis.