Levels of Interleukin‐18 and Endothelin‐1 in Children with Henoch‐Schönlein Purpura: A Study from Northern India

Henoch‐Schönlein purpura (HSP) is an acute systemic vasculitis with unknown etiology, although several studies have found HSP to be related to cytokines such as tumor necrosis factor α, interleukin (IL)‐1, and adhesion molecules. In the present study we determined the levels of cytokines such as IL‐18 and endothelin‐1 (ET‐1) in children with HSP. Subjects were divided into three groups (group 1, 20 subjects with HSP; group 2, 10 subjects belonging to group 1 during their follow‐up 4 to 6 months later; and group 3, 16 controls who were healthy siblings of the subjects). IL‐18 and ET‐1 levels were determined using enzyme immunoassay and expressed as mean ± standard deviation. We observed higher IL‐18 levels in children with HSP (767.6 ± 145.1 pg/mL) than in controls (614.6 ± 66.54 pg/mL, p > 0.05), but IL‐18 levels were found to be significantly lower in subjects with HSP in remission (502.7 ± 60.81 pg/mL) than in those who were in an active phase (1,050 ± 244.5 pg/mL, p < 0.05, n = 10). ET‐1 levels were found to be significantly higher in subjects with HSP (1.93 ± 0.19 pg/mL) than in controls (1.10 ± 0.13 pg/mL, p < 0.05), although no significant difference was observed in ET‐1 levels between subjects in group 1 (1.88 ± 0.30 pg/mL) and group 2 (1.91 ± 0.120, p > 0.05, n = 10). A positive correlation was observed between IL‐18 and ET‐1 levels in subjects with HSP (correlation coefficient [r] = 0.5254, p < 0.01). These results suggest that levels of IL‐18 and ET‐1 are worth monitoring during the clinical course of the disease, but caution must be exercised in extrapolating data based on small study samples.