Indirect immunofluorescence assay with HeLa cell chips. Serum samples containing the probe antibodies were incubated with the cell chips, which were visualized using an Olympus FV1000 confocal laser-scanning microscope at ×40 magnification. (A) KD serum exhibited significantly higher immunoreactivity with proteins from HeLa cells compared with (B) FC and (C) HC serum. (D) Positive control (serum samples replaced with anti-ACTB antibody) and (E) blank control (serum samples replaced with PBS) groups. (F) Semi-quantitative analysis of the fluorescence intensity of KD, FC, and HC. Positive recognition of proteins in the HeLa cells by antibodies in the serum appear green, and the nucleus is stained blue. ACTB, β-actin; FC, febrile control; HC, healthy control; KD, Kawasaki disease.