A Flow Chamber Assay for Studying MAIT Cell Trafficking.

Human MAIT cells show little expression of the selectin CD62L and the chemokine receptor CCR7, which are important for entering lymph nodes, and high expression of selectin ligands and chemokine receptors that mediate trafficking into inflamed tissue. Extravasation of leukocytes into tissue requires sequential steps including rolling, firm arrest, crawling, and transendothelial migration, and can be modeled using endothelial cell monolayers in flow chambers that approximate the sheer stress found in post-capillary venules. Using MAIT cells purified from elutriated lymphocytes by fluorescence-activated cell sorting, we have used flow chambers to demonstrate roles for individual chemokine receptors in specific steps required for extravasation. These methods provide a general way to study the molecular mechanisms underlying MAIT cell trafficking from blood into tissue.