Mediation of pulmonary immunity and hypersensitivity by neuropeptides.

Noxious challenges and inflammatory reactions in pulmonary tissue selectively stimulate different subsets of peptidergic nerve fibers to release distinct neuropeptides, that elicit local and systemic responses similar to those of immediate hypersensitivity. The sensory neuropeptides affect functions of leukocytes, epithelial glands, and smooth muscle cells directly through receptor-medicated processes, and indirectly, through the actions of mediators released from mast cells stimulated by the peptides. The specificity of neuropeptide recognition by pulmonary lymphocytes, smooth muscle cells, mast cells and basophils, and the functional diversity of these neuropeptides suggests that the nervous system modulates immediate and delayed hypersensitivity responses in the lung by unique mechanisms.