Pathways of T lymphocyte recirculation

Naive T cells preferentially leave the blood and enter lymph nodes across the High Endothelial Venules (HEVs).  Dendritic cells bearing antigen enter the lymph node through lymphatic vessels.  If the T cells recognize antigen, there are activated, and they return to the circulation through the efferent lymphatics and the thoracic duct, which empties into the superior vena cava, then into the heart, and ultimately into the arterial circulation.  Effector and memory T cells preferentially leave the blood and enter peripheral tissues through venules at sites of inflammation.  Recirculation through peripheral lymphoid organs other than lymph nodes is not shown.