Two-Photon Imaging of Lymphocyte Motility and Antigen Response in Intact Lymph Node

TLDR

Lymphocyte motility is essential for trafficking and antigen‑cell contact, yet prior visualization was limited to in vitro systems. The study uses two‑photon laser microscopy to image individual lymphocytes deep within intact lymph nodes. Two‑photon laser microscopy enables real‑time imaging of lymphocyte dynamics in the native lymph node environment. T cells move at over 25 µm/min—five to six times faster than B cells—and antigenic challenge induces swarming and clustering, revealing behaviors fundamental to immune initiation.

Abstract

Lymphocyte motility is vital for trafficking within lymphoid organs and for initiating contact with antigen-presenting cells. Visualization of these processes has previously been limited to in vitro systems. We describe the use of two-photon laser microscopy to image the dynamic behavior of individual living lymphocytes deep within intact lymph nodes. In their native environment, T cells achieved peak velocities of more than 25 micrometers per minute, displaying a motility coefficient that is five to six times that of B cells. Antigenic challenge changed T cell trajectories from random walks to “swarms” and stable clusters. Real-time two-photon imaging reveals lymphocyte behaviors that are fundamental to the initiation of the immune response.