Dendritic cells and macrophages neurally hard-wired in the lymph node

Abstract

The neural hard-wired pathways in which the lymphoid organs are innervated by the nervous system is of special interest with respect to suggested afferent and sensory systems informing the central nervous system about the status of the immune system. Until today efferent also like afferent innervation seem to be unspecific, targeting many types of cells by affecting many cells at the same time. We for the first time show that antigen presenting cells (APC) are abundantly innervated in the T-cell enriched area, the subsinoidal layer and the cortical extrafollicular zone of lymph nodes in rats by a mesh of filamentous neurofilament positive structures originating from single nerve fibers and covering each single APC similar to a glass fishing float, so that we termed them "wired" APC (wAPC). These wAPC also found in humans seem to be restricted to the cell body, not to follow membranous extensions, they may be dynamic and receptive as MAP2 is expressed and axonal growth cones can be detected and they probably lack vesicular activity through missing synaptophysin expression. The specific innervation targeting single cells which show a distribution divided in several areas in one lymph node suggests a form of topographically organized afferent sensory system.