Single-cell analysis of cytotoxic T cell function by intravital multiphoton microscopy.

Novel nonlinear optical imaging modalities, most prominently multiphoton microscopy, allow for the direct in vivo visualization of dynamic biological processes in experimental animals at high spatial and temporal resolution. This has led to important new insights into the orchestration of adaptive immune responses. Here we describe in detail a technique that allows for the monitoring of the cytotoxic function of CD8(+) effector T cells in tumor-draining lymph nodes of mice at the single-cell level in vivo using multiphoton intravital microscopy.