Serum human cartilage glycoprotein 39 as a marker of arthritis associated with inflammatory bowel disease.

BACKGROUND Common blood markers of arthritis are difficult to interpret in arthritis associated with inflammatory bowel disease (IBD) owing to the coexistence of two inflammatory events. No specific serological disease marker is available for IBD. OBJECTIVE To determine a value of serum human cartilage glycoprotein 39 (HC gp39) as a marker of arthritis associated with IBD. METHODS Serum levels of HC gp39 and ultrasensitive C reactive protein (CRP) were determined in 121 patients with IBD: 58 without arthritis (IBD-nonA) and 63 with arthritis (IBD-A), and in 20 healthy controls. IBD was classified as active (aIBD) and non-active (naIBD), and patients with IBD-A were classified as type I, II, and III arthritis by clinical activity indices. RESULTS HC gp39 was higher in IBD-A than in IBD-nonA (p<0.001) and controls (p<0.01), while no difference was found between IBD-nonA and controls. CRP was increased in both IBD-A and IBD-nonA compared with the controls (p<0.01 and <0.05, respectively) and in aIBD-nonA v naIBD-nonA (p<0.05), but no difference in CRP was found between aIBD-A and naIBD-A. Finally, a correlation was found between the number of affected joints (NAJ) and HC gp39 (r = 0.6, p<0.001). DISCUSSION Increased serum levels of HC gp39, which were higher in IBD-A than in IBD-nonA, suggest that this substance might be a marker of arthropathy in IBD. HC gp39, because of its relationship with NAJ in IBD-A, may also be proposed as a disease activity marker in arthritis associated with IBD.