Transmigration of leukocytes across epithelial monolayers

Abstract

Migration of leukocytes through epithelial monolayers represents an essential step in the generation of an inflammatory response and is often seen in inflammatory conditions such as Crohn’s disease (Matthews et al., Toxicol Pathol 42:91–98, 2014) and asthma (Lambrecht and Hammad, Nat Med 18:684–692, 2012). Transepithelial migration involves adhesion to the basal surface of the epithelium before migration through the epithelial cell layer to the apical surface. Analyzing this process can present a technical challenge due to complications of using a coculture model and trying to recapitulate an intact monolayer. Here we describe two methods of assessing transepithelial migration based on a Transwell assay, the first of which measures the apical–basal migration of epithelial cells and the second “Inverted” transwell assay that measures basal–apical transmigration of leukocytes and therefore more closely mimics the in vivo process.