Assaying antigen-specific T cell trans-endothelial migration in vitro with the Transwell system: application in tumor immunology.

T cells play a key role in tumor immune surveillance. Trafficking of T cells to the tumor microenvironment is critical for the success of cancer immunotherapies. The process of T cell trafficking involves a sequence of steps: initial rolling along the endothelium, firm adhesion, subsequent extravasation, and directed chemotactic movement toward the tumor site. It is emerging that tumor vasculature constitutes an important barrier to T cell infiltration. In this protocol, we summarize a method for assessing antigen-specific CD8⁺T cell trans-endothelial migration in vitro using the Transwell system. This technique is vital for studying the mechanisms of T cell extravasation and their interactions with the vascular endothelium, and provides a controllable experimental setup to investigate T cell trans-endothelial migration.