OA patients had normal IL-7 (median 13.1 pg/ml, range 9.7 to 19 pg/ml) and patients with other inflammatory conditions (including active colitis, psoriatic arthritis, ankylosing spondylitis, gout, reactive arthritis) showed reduced levels only in 14 out of 96 individuals (median 12.7 pg/ml, range 7 to 29.6 pg/ml). This evidence concerns the gene IL7 and reactive arthritis.