Plasma immunoreactive endothelin (iET) levels were investigated in pat
ients with Kawasaki disease (KD). The iET level was 2.49 +/- 0.13 pg/m
L in KD patients and 1.32 +/- 0.06 in age-matched control subjects, sh
owing a significant increase with KD. The iET level was not increased
in patients with febrile inflammatory diseases of bacterial origin wit
hout KD (non-KD group). Parameters indicating an inflammatory reaction
, such as C-reactive protein, platelet count, white blood cell count,
and interleukin-6 level, were increased in the KD patients. However, t
hey were similarly increased in the patients with febrile diseases of
bacterial origin and showed no significant differences between the two
groups. This study is the first to report that plasma iET levels are
elevated in a disease mainly involving vasculitis. These results sugge
st that blood iET levels are increased in KD patients as a result of t
he associated vascular endothelial damage and that iET can be a useful
marker for the diagnosis of KD.