Reduced Frequencies of Peripheral Interferon-γ-Producing CD4+ and CD4– Cells during Acute Kawasaki Disease

BACKGROUND: This study was performed to analyze the frequencies of peripheral interferon (IFN)-gamma-producing cells at the single-cell level and to determine concentrations of circulating IFN-gamma in the acute and subacute phases of Kawasaki disease (KD). METHODS: Ten patients with KD were studied and seven healthy children were selected as control subjects. Using immunofluorescent detection of intracellular IFN-gamma in CD4-positive and CD4-negative cells, the frequencies of IFN-gamma-producing cells in peripheral blood mononuclear cells were studied. Circulating IFN-gamma levels were measured by enzyme-linked immunosorbent assay. RESULTS: The frequencies of peripheral blood CD4+ and CD4- IFN-gamma-producing cells in acute-phase KD patients were significantly lower than in subacute-phase KD patients and control children (p < 0.05). CD4- cells, thought to be mainly composed of CD8+ cells, appeared to be more responsible for the reduced frequencies of total IFN-gamma-producing cells than CD4+ cells. There were, however, no differences in the frequencies of IFN-gamma-producing cells between KD patients in the subacute phase and control children. In contrast, serum IFN-gamma levels were higher in KD patients in the acute phase than in the subacute phase (p < 0.05). CONCLUSIONS: The above results show increased levels of circulating IFN-gamma and decreased emergence of peripheral IFN-gamma-producing cells in acute KD patients, suggesting transient infiltration of activated IFN-gamma-producing cells into the inflammatory sites during acute KD. These findings also support the hypothesis that IFN-gamma plays an important role in the pathogenesis of KD-related vasculitis.