Intravital Imaging of Intraepithelial Lymphocytes in Murine Small Intestine.

Intraepithelial lymphocytes expressing γδ T cell receptor (γδ IEL) play a key role in immune surveillance of the intestinal epithelium. Due in part to the lack of a definitive ligand for the γδ T cell receptor, our understanding of the regulation of γδ IEL activation and their function in vivo remains limited. This necessitates the development of alternative strategies to interrogate signaling pathways involved in regulating γδ IEL function and the responsiveness of these cells to the local microenvironment. Although γδ IELs are widely understood to limit pathogen translocation, the use of intravital imaging has been critical to understanding the spatiotemporal dynamics of IEL/epithelial interactions at steady-state and in response to invasive pathogens. Herein, we present a protocol for visualizing IEL migratory behavior in the small intestinal mucosa of a GFP γδ T cell reporter mouse using inverted spinning disk confocal laser microscopy. Although the maximum imaging depth of this approach is limited relative to the use of two-photon laser-scanning microscopy, spinning disk confocal laser microscopy provides the advantage of high speed image acquisition with reduced photobleaching and photodamage. Using 4D image analysis software, T cell surveillance behavior and their interactions with neighboring cells can be analyzed following experimental manipulation to provide additional insight into IEL activation and function within the intestinal mucosa.