VCAM1 and vasculitis: An increase in Th17 cell numbers likely reflects active vasculitis [14], and an increase in the number of eosinophils or WBCs might induce upregulation of the expression of ICAM-1 or VCAM-1 on vascular endothelial cells; inflammatory cells such as eosinophils and lymphocytes, including Th17 cells, then migrate extravascularly into the colonic submucosa.