Expression of a monocarboxylate transporter in reticular cells of the mouse lymph node and its involvement in the uptake of exogenous particles

Abstract

The monocarboxylate transporter (MCT)-1 plays an important role in the transfer of monocarboxylatemetabolites such as lactate, ketone bodies, and acetic acid. The present study revealed theselective localization of MCT1 in reticular cells of the murine lymph node. An intense MCT1 immunoreactivitywas found in the reticular cells forming a cellular network together with sinusliningcells in the medullary sinuses and in cells covering the inside of subcapsular sinuses.Electron-microscopically, MCT1 was localized along the plasma membrane of the reticular cells.The medullary reticular cells vigorously ingested carboxylate-modified latex particles, but any reticularcells within the cortical lymphoid follicles and medullary cords neither expressed MCT1nor incorporated latex particles. MCT1-immunoreactive reticular cells also expressed LYVE-1,which is a hyaluronan receptor abundant in both the lymphatic endothelium and hepatic sinusoidalepithelium. The selective localization of MCT1 and LYVE-1 suggests a high level of activity forlymphoid reticular cells in the uptake of carboxylate-modified and hyaluronate waste substancescirculating in the body.