Increased α1-antitrypsin levels in acute-phase Kawasaki disease as shown by SELDI-TOF MS analysis.

Various agents have been suggested as causal or associated factors in the pathogenesis of Kawasaki disease (KD); however, the underlying factors of KD remain unknown. Plasma exchange is one of the most effective treatments for the acute phase of KD. This indicates that plasma may contain factors associated with the pathogenesis of KD. To search for proteins that may be involved in KD pathogenesis, we analyzed serum proteins with surface-enhanced laser desorption/ionization time of flight mass spectrometry (SELDI-TOF MS). Serum samples were obtained from 17 KD patients. Serum from six of the patients was collected during acute phase before acetylsalicylic acid (ASA) and intravenous immunoglobulin administration (phase A1), during remission with ASA (phase A2), and during remission without any medication (phase A3). Serum from the remaining 11 patients was collected for phases A1 and A2 only. There were two age- and sex-matched control groups comprising 8 afebrile healthy children (group B) and 8 febrile children with several infectious diseases (group C). There were no statistical differences in laboratory examination between phase A1 and group C except for albumin level, alanine aminotransferase, or sodium level. Serum samples were analyzed by SELDI-TOF MS after purification. We detected five peaks, i.e., those were specifically increased or decreased during phase A1, and identified 1 of these as α1-antitrypsin (α1-AT). α1-AT can inhibit neutrophil elastase activity. This elastase is thought to play a role in coronary artery damage. Our findings present an interesting starting point for further investigations into the pathophysiology of KD.