Serum interleukin-18 in children with Henoch-Schonlein purpura: a promising marker of disease activity?

Henoch-Schönlein purpura (HSp) is the most common systemic vasculitis of childhood with typical skin involvement and concurrent signs involving joints, gastrointestinal tube and kidney. HSp pathogenesis is still far to be definitely unraveled, though a knotty cytokine complex is believed to contribute in its intimate processes. Aim of our evaluation was to establish the relationship between serum levels of interleukin (IL)-18 and disease outcome and establish its feasibility to provide a marker of disease activity or even a prognostic tool in the clinical practice. We examined clinical/laboratory variables and serum IL-18 in 17 unselected children hospitalized during the last year for HSp, diagnosed by EULAR/PRINTO/PRES criteria; the same patients were re-evaluated after 6 months too. All results were compared with 25 age-matched healthy controls. IL-12 and IL-6 were also evaluated in a cohort of the same patients and compared with controls. General and clinical variables (sex, edema of the extremities, gastrointestinal or renal complications, relapses and renal involvement at 6 months) had no relationship with cytokine levels. Serum IL-18 and IL-6 levels were found significantly increased at diagnosis in HSp patients when compared with healthy controls. After 6 months serum IL-18 and IL-12 levels were significantly decreased in patients, while IL-12 and IL-6 levels were significantly increased if compared with healthy controls. Though preliminary and expecting further confirmation on a larger sample, our data support the conclusion that serum IL-18 levels reflect HSp activity.