Leukocyte Adhesion Factor Mac-1 Expression on Granulocyte Associates with Vasculitis in Kawasaki Disease

We have revealed massive expression of Ca binding protein myeloid-related protein (MRP) on circulating leukocyte in acute phase of Kawasaki disease. Newton et. al. (J Immunol 1998 160:1427) reported MRP reinforce the ability of adhesion molecule Mac-1, which suggest the keen relationship between MRP, Mac-1 and vasculitis. We quantified leukocytes Mac-1 expression in Kawasaki disease, and evaluated the adhesion ability between cultured human coronary artery endothelial cell and Kawasaki disease patients' peripheral leukocyte. (Materials and Methods) mRNA was extracted from the Kawasaki disease patients' leukocyte (n=21) and was converted to cDNA by RT-PCR, and Mac-1 expression was evaluated by quantitative PCR (Applied Biosystems; GeneAmp 5700). The patients' leukocyte, labeled with BCECF-AM, exposed to cultured human coronary artery endothelial cell, and leukocyte adhesion assay was performed. (Result) Mac-1 expression was a peak on acute phase of Kawasaki disease and significantly decreased after 1 month of onset. The patients' leukocyte adhesion ability to endothelial cell was significantly increased, which was significantly inhibited by addition of anti-Mac-1 antibody. We postulated Mac-1 play the key role for leukocyte invasion into endothelium, which is the initial step for causing vasculitis.