IL-6 and MMP-3 were also secreted from unstimulated OA FLS, although the levels were lower than those from RA FLS (IL-6; RA: 1,393 ± 493 mg/dl (n =3), OA: 171 ± 83 mg/dl (n =2), P <0.05, MMP-3; RA: 2135 ± 644 mg/dl, OA: 296 ± 50 mg/dl, P <0.05). Here, IL6 is linked to rheumatoid arthritis.