Background & Aims: Integrins play diverse roles in cel- presenting cells, and may direct and regulate cellular lular actions and signaling in the immune system. In migration within tissues, cellular differentiation, and re-the context of mucosal immune responses, the integrin sponses to inflammatory stimuli through interactions a4b7 has received particular attention because of its with these adhesion proteins and extracellular matrix intimate involvement in lymphocyte recruitment to nor- components such as fibronectin. 3, 7, 8 These diverse cellular mal gastrointestinal mucosa and associated lymphoid adhesion events likely contribute to both normal and tissue. The aim of this study was to determine the pathological mucosal immune and inflammatory re-functional relevance of a4b7 in the pathogenesis of sponses. colonic inflammatory disease using the colitic cotton-