Nervous‐system‐associated mast cells: Gatekeepers of neural and immune interactions

Although mast cells have been described in or near certain areas of the central and peripheral nervous systems, the present investigation demonstrates that nervous‐system‐associated mast cells in the mouse are strategically located along the vasculature that supply or drain these tissues. Of particular interest are the mast cells present in the velum interpositum of the transverse fissure. These mast cells are distributed along blood vessels that perfuse or drain the thalmus, hippocampal formation, corpus striatum, corpora quadrigemini, and the choroid plexi of the lateral ventricles. Such a distribution suggests that mast cells and their vasoactive products (e.g., histamine, serotonin, leucotrienes) may be involved in regulating the regional permeability of the vessels supplying or draining these important brain regions. In addition, numerous periganglionic mast cells were found to be distributed in and around vessels of the dorsal root ganglia and spinal roots. Consequently, periganglionic mast cells may control the permeability of the blood vessels perfusing or draining the dorsal root ganglia and spinal roots and thereby control the ability of immune components to access these tissues, the spinal cord, and the adjacent subarachnoid space. Thus, nervous‐system‐associated mast cells may serve as cellular gatekeepers of interactions between the immune and nervous systems.