Increased serum interleukin-32 levels in patients with Behçet's disease

Interleukin (IL)-32 is known to act as a proinflammatory cytokine and is likely involved in several chronic inflammatory diseases. The aims of this study were to investigate whether serum IL-32 levels are elevated in patients with Behçet's disease (BD) and to identify the correlation between IL-32 levels and disease activity.

We enrolled 50 patients with BD and 35 healthy controls. Serum IL-32 levels were measured using an enzyme-linked immunosorbent assay. Serum levels of IL-12p70, IL-17A, IL-1β, IL-6 and IL-8 were measured using a multiplex assay. BD disease activity was determined using the Behçet's Disease Current Activity Form (BDCAF).

Serum IL-32 levels were significantly higher in patients with BD (median [interquartile ranges], 0.4 [0.1-736.2] pg/mL) than in healthy controls (0.1 [0.1-14.7] pg/mL, P = 0.041). When patients with BD were divided into active (patient index score ≥ 2 or transformed index score ≥ 5 in the BDCAF) and inactive groups, IL-32 levels tended to be higher in patients with active BD, although this observation was statistically insignificant. Serum levels of IL-12p70, IL-17A, IL-1β, IL-6 and IL-8 did not differ between active and inactive groups. There was a weak positive correlation between serum IL-32 levels and BDCAF scores (R = 0.301, P = 0.033). BD patients with recent arthralgia exhibited higher IL-32 levels than did those without (P < 0.001).

These findings suggest that IL-32 may play a minor role in the pathogenesis of BD.