Principal dynamics leading to T cell priming by Ag-DCs in the T cell zone of a LN during an immune response. T cells enter through HEVs while DCs enter through ALs. Motile T cells exhibit short-term persistence but maintain a longer- term random walk as they scan DCs for cognate antigen, exhibiting characteristic free path lengths, speed distributions, and motility coefficients. This is supported by a LN environment that contains a dense FRC network and chemical signals. Once cognate antigen is located, T cells proceed through a multi-phase activation process, with Phase 1, transient interactions, and Phase 2, more prolonged interactions that include T cell clusters and swarms, defined based on 2PM data (Miller et al. 2004b; Mempel et al. 2004), (see above section 2.2 for greater details on phases). Ultimately, successful interactions lead to T cell activation, proliferation and egress to site of infection.