How do lymphocytes find their way in vivo?

How do lymphocytes find their way in vivo? Lymphocytes are mobile and travel from blood to lymph and then return to blood, which ensures a coordinated expression of immunological functions. In lymph nodes (LN) and Peyer's patches, the port of entry for naive T and B cells is the high endothelial venules (HEVs). The endothelial cells of HEVs are characterized by the luminal presentation of various adhesion molecules and chemokines. Some of the endothelial adhesion molecules are responsible for the tissue-specific trafficking of lymphocytes by giving lymphocytes positional cues, and hence are called vascular addressins. The peripheral LN addressins (PNAd) include several sialomucins and the mucosal LN addressin is MAdCAM-1. The complementary lymphocyte homing receptors for these addressins