Blood serum interleukin-1 receptor antagonist in pars planitis and ocular Behcet disease

PURPOSE: To determine the levels of interleukin-1 receptor antagonist (IL-1ra) in the blood serum of patients with idiopathic bilateral pars planitis and Behcet disease. METHODS: Five milliliters of blood was withdrawn from the cubital vein of 91 patients (58 with the ocular type and five with the combined type of Behcet disease; 28 with pars planitis) and 36 volunteers. Serum was separated from these samples and stored at -70 C until assayed. Interleukin-1 receptor antagonist levels were determined by human IL-1ra enzyme-linked immunosorbent assay kits, In patients not receiving any systemic medication, one serum sample was obtained before initiating treatment and another when the patients had been under full medical treatment for 6 weeks or more. RESULTS: Pretreatment mean +/-SD serum IL-1ra levels were 320 +/- 32 pg/ml for the patients with pars planitis, 380 +/- 54 pg/ml for patients with Behcet disease, and 271 +/- 29 pg/ml for the control subjects (no statistical significance). During treatment, a mean serum level of 352 +/- 37 pg/ml was observed in patients with pars planitis (not significantly different from control subjects) and 538 +/- 79 pg/ml in patients with ocular Behcet disease (P = .0116 compared with control subjects). The greatest increase in IL-1ra levels was observed in patients with Behcet disease who received a combination of cyclosporine and corticosteroids. CONCLUSIONS: Because IL-1ra is one of the natural immunomodulating molecules, the significant increase of serum IL-1ra levels, especially after combined treatment with cyclosporine and corticosteroids, could indicate that the therapeutic effects of this regimen may be mediated through its effects on this molecule.