Detection of auto-antibodies against a 70 kDa protein derived from vascular smooth muscle cells in patients with Kawasaki disease

The aetiology and pathogenesis of Kawasaki disease (KD) remain unknown. To investigate the pathogenesis of vasculitis in KD, we tested for the presence of auto-antibodies against a component of vascular smooth muscle cells in the sera of patients with KD. Sera from 48 patients with KD, as well as sera from 14 sick children and from 22 healthy children, were examined for reactivity to both coronary arterial wall tissues and cultured smooth muscle cells (CSMC) derived from human coronary artery, using immunofluorescence and Western immunoblot assay techniques. Sera from 16 of 48 patients with KD gave positive immunoreactions to the vascular walls of coronary artery with fluorescein isothiocyanate-labelled rabbit anti-human IgA antibodies. In Western immunoblot assays, the sera from 15 of 34 and 10 of 31 patients with KD showed positive reactions against a 70 kDa protein from CSMC with IgA and IgM antibodies, respectively. Positive immunoreactivity of sera from patients with KD, determined either by immunofluorescence studies or by Western immunoblotting, was detected more frequently (P