Imaging the Single Cell Dynamics of CD4+ T Cell Activation by Dendritic Cells in Lymph Nodes

Abstract

The adaptive immune response is initiated in secondary lymphoid organs by contact between antigen-bearing dendritic cells (DCs) and antigen-specific CD4+ T cells. However, there is scant information regarding the single cell dynamics of this process in vivo. Using two-photon microscopy, we imaged the real-time behavior of naive CD4+ T cells and in vivo–labeled DCs in lymph nodes during a robust T cell response. In the first 2 h after entry into lymph nodes, T cells made short-lived contacts with antigen-bearing DCs, each contact lasting an average of 11–12 min and occurring mainly on dendrites. Altered patterns of T cell motility during this early stage of antigen recognition promoted serial engagement with several adjacent DCs. Subsequently, T cell behavior progressed through additional distinct stages, including long-lived clusters, dynamic swarms, and finally autonomous migration punctuated by cell division. These observations suggest that the immunological synapse in native tissues is remarkably fluid, and that stable synapses form only at specific stages of antigen presentation to T cells. Furthermore, the serial nature of these interactions implies that T cells activate by way of multiple antigen recognition events.

3D and 4D imaging of immune cells in vitro and in vivo

“…Both lymph node preparations have yielded similar values for the migratory activity of DC and T cells (Lindquist et al 2004;Mempel et al 2004;Miller et al 2004b). The in vivo measurements of cell migration and communication are also in good agreement with microscopy studies performed in situ in excised, intact murine LNs (Bousso and Robey 2003).…”

Characterizing T Cell Movement within Lymph Nodes in the Absence of Antigen

“…From these experiments, the locations of individual T cells moving in lymphoid organs are obtained as a function of time (5)(6)(7)(8). The instantaneous and mean velocities of T cells, their mean free paths, and their trajectories in the presence and the absence of Ag-presenting dendritic cells can thus be determined.…”

“…The experimental data used to calibrate our model was taken from four different publications (5)(6)(7)(8). These papers were chosen because they presented the mean displacement of T cells as a function of the square root of time, which we used to fit our T cell movement model.…”

“…The experimental instantaneous velocity, v exp , is computed from the distance traveled by a T cell in the xy-plane over a short time interval (ϳ10 s) (5)(6)(7)(8). Over this time interval, some T cells are paused, some T cells are moving, and some will experience both states sequentially.…”

T cell–antigen-presenting cell interactions visualized in vivo in a model of antigen-specific inflammation

“…More recently in vivo documentation of T cell and APC trafficking and interactions have been documented, especially through the use of two photon confocal microscopy [4,5,6,7,8,9]. The majority of these studies involve the lymph node or other lymphoid organ such as the bone marrow or thymus [10,11].…”