Increased Production of Serum IgA-class Antibody to Lipid A in Kawasaki Disease

Abstract

Objective: We recently reported that lipopolysaccharide (LPS) is bound to circulating neutrophils in the acute phase of Kawasaki disease (KD). The aim of the present study is to investigate the serum response to LPS in KD.Methods: We measured the serum levels of IgG-, IgM- and IgA-class antibodies (Abs) to lipid A, a toxic site of LPS, using ELISA in 20 patients with KD, 11 patients with gram-negative bacterial infection (GNBI), 27 healthy children, and 12 healthy adults. Results: The serum levels of anti-lipid A IgG, IgM and IgA tended to increase with advancing age in healthy children older than 6 months of age. The mean level of anti-lipid A IgM in the acute phase of GNBI and the mean levels of anti-lipid A IgM and IgA in the acute phase of KD were found to increase significantly, in comparison to the age-matched controls. Furthermore, the mean level of anti-lipid A IgA also showed a significant increase from the acute through the subacute phases of KD. Regarding the IgA-subclass response, higher titers of anti-lipid A specific Ab were seen in the IgA2 subclass than in the IgA1 subclass. Conclusion: These findings indicate that KD patients demonstrate an intense response to lipid A in the IgA, especially IgA2-subclass, thus suggesting that an unusual activation of the mucosal immune response to a ubiquitous antigen derived from gram-negative bacteria may be involved in the pathogenesis of KD.