Real-time imaging of lymphocytes in vivo

Abstract

New preparations, fluorescent probes and imaging techniques are providing the means to observe the behavior of cells in the tissue environment of lymphoid organs. In particular, when combined with two-photon laser microscopy, intravital imaging of surgically exposed lymph nodes provides a unique view of lymphocyte migration and antigen presentation as it occurs within the living animal. The view is emerging that lymphocytes migrate randomly within lymphoid organs, and that lymphocyte contact with antigen-presenting cells may be a stochastic process rather than one guided by chemokine gradients.

Figure 1

The strengths and weaknesses of model systems in current use for the real-time imaging of lymphocytes. EC, endothelial cell.

Figure 2

Intravital two-photon microscopy: an anesthetized mouse with surgically exposed lymph node on the microscope stage. Details of the preparation have been described [23].

Figure 3

Intravital two-photon images of T cells in the inguinal lymph node of an anesthetized mouse. (a) Trajectories of four separate cells at varying times. The colors represent cells at different depths, ranging from ∼100 to 150 μm below the surface of the lymph node, with blue representing the bottom and red the top of the imaging volume. Scale bar: 25 μm. (b) T cells (green), vessels and fibers (both red) labeled via tail vein injection with tetramethylrhodamine dextran. Scale bar: 50 μm.