ABSTRACT
Neuroendocrine–immune communication influences mammalian development, cellular differentiation, normal functions of organs in both systems, inflammatory responses to microbial invasion and tissue injury, tissue repair, and the pathogenesis of diverse diseases. Morphometric enumeration of nerve endings in lymphoid tissues has established proximity and connections with most T lymphocytes and mast cells, including occasional plasma membrane intercalations. Lymphoid organs are heavily supplied by noradrenergic autonomic nerves and cholinergic nerves, which also contain neuropeptide Y, somatostatin, galanin, and vasoactive intestinal peptide (VIP), and by the nonadrenergic and noncholinergic sensory nerves, which contain the tachykinins Substanz P (SP) and neurokinin A as well as calcitonin gene-related peptide. The finding of immunologically relevant concentrations of VIP and SP in broncho-alveolar lavage fluid after intratracheal antigen challenge of sensitized mice provided an opportunity to evaluate their roles in mobilizing and regulating T-cell and some other immune responses in the pulmonary parenchymal compartment.
