LYVE-1 expression on high endothelial venules (HEVs) of lymph nodes

LYVE-1 (lymphatic endothelium hyaluronan receptor) has been identified as a powerful marker for lymphatic endothelium. Apart from lymphatic endothelium, LYVE-1 is expressed in normal liver blood sinusoids, spleen endothelium and activated tissue macrophages. LYVE-1 has not been detected in blood vascular endothelium with the exception of blood vessels in the lung. High endothelial venules (HEVs) belong to the vascular compartment of lymph nodes. They are the major site of entry for circulating lymphocytes into the node. HEVs are characterized by cuboidal endothelial cells, the existence of discontinuous junctions between these endothelial cells, and the presence of large numbers of lymphocytes within their walls. 40 paraffin-embedded lymph node biopsy specimens from newly diagnosed patients with non-Hodgkin lymphoma were evaluated as well as 10 lymph node biopsy specimens from adult patients with reactive lymphadenitis, and 10 normal, non-metastatic lymph nodes obtained from adult patients during cancer surgery served as controls. Samples were fixed in 10% buffered formalin, paraffin embedded, and stained with hematoxylin and eosin for histopathological evaluation. Sections were also evaluated with mouse monoclonal antibodies against LYVE-1 and CD34, and expression of both LYVE-1 and CD34 was demonstrated in HEVs. LYVE-1 expression was also found on the endothelial cells of the lymphatic sinus and in reticular cells in the lymph nodes.