The alveolar epithelial type I-like cell line as an adequate model for leukocyte migration studies in vitro

The lung is unique as leukocytes not only migrate into the bronchoalveolar space but also return to the parenchyma and then via the lymphatics to the draining lymph node. The aim of this study was to investigate the migration of leukocytes via an epithelial monolayer in a Transwell system against a chemokine gradient. Rat type I-like R3/1 alveolar epithelial cells were cultivated on a Transwell polyester membrane (pore diameter 3 microm) for 3 days until a monolayer was formed. The tightness of the monolayer was determined by transepithelial transport of horseradish peroxidase. Isolated human and rat peripheral blood mononuclear cells (PBMC) were placed in the upper chamber, and different concentrations of monocyte chemotactic protein-1 (MCP-1) in the lower chamber. The transmigration of PBMC was quantified and investigated by light and transmission electron microscopy. PBMC migrated through the epithelial cell barrier intercellularly as well as transcellularly. The migration of PBMC against the MCP-1 gradient was dose dependent. The results indicate that this model could help in the study of key events involved in chemokine-induced cell migration from the airways into tissue.