Evidence for a critical T cell - B cell interaction in tolerance induced by anti-CD45RB

RESULTS: Splenic T cell migration to CCL19 or CXCL12 is enhanced by, but does not require, S1P receptor stimulation. In contrast, lymph node T cell migration to CXCL12 but not CCL19 requires both chemokine and S1P receptor stimulation. The requirement for CXCR4 and S1PR stimulation of lymph node T cells is particularly important for mechanisms involving transendothelial migration of T cells. The results also demonstrate that: 1) splenic versus lymph node T cells use different molecular migration mechanisms; 2) CCR7 and CXCR4 stimulation engage different molecular migration mechanisms; and 3) S1P and FTY720 have distinct S1PR agonist and antagonist properties.