Serum levels of interleukin-18 are elevated in the subacute phase of kawasaki syndrome.
Elevations of various cytokines, including Th1 and Th2 cytokines, have been reported in the acute phase of Kawasaki syndrome (KS). As interleukin (IL)-18 plays an important role in the Th1 cell response, investigating the relevance of IL-18 in KS should be helpful in determining the pathophysiology of KS. Therefore, we examined the IL-18 values in KS. Serum IL-18 values were measured by an enzyme-linked immunosorbent assay. Samples were obtained from 41 patients in the acute and subacute phase of KS, 35 age-matched febrile controls and 13 afebrile controls. No difference was observed in the values of white blood cell counts or C-reactive protein between acute-phase KS patients and febrile controls. On the contrary, acute-phase KS patients showed a significantly lower mean IL-18 value (398 +/- 206 pg/ml) than that of febrile controls (584 +/- 307 pg/ml) (p = 0.006). Subacute-phase KS patients showed a significantly elevated level of IL-18 (517 +/- 276 pg/ml) compared to acute-phase patients (p = 0.0008). The IL-18 values in the subacute-phase patients showed a significant positive correlation with the duration of fever (r = 0.427, p = 0.0055) and also with the presence of coronary artery abnormalities (r = 0.332, p = 0.0340). The incidence of elevated IL-18 values in the subacute-phase patients was significantly higher than that in the afebrile controls (p = 0.048). Patients with KS showed normal IL-18 values in the acute phase and elevated values in the subacute phase. IL-18 pathways were activated in the subacute phase of KS, and subacute IL-18 values might be reflected in the severity of KS.