NEURAL REGULATION OF NEUTROPHIL INVOLVEMENT IN PULMONARY INFLAMMATION

1. The high viscoelastic property of neutrophils is the major factor c ontributing to their extensive accumulation (more than 50% of circulat ing neutrophils) in the pulmonary microvasculature. 2. The cholinergic parasympathetic and adrenergic sympathetic nerves modulate the size o f the pulmonary neutrophil pool by regulating arterial and venous pres sures, increases in which promote or reduce neutrophil transit times, respectively. 3. Biochemical factors, such as the cytokines and comple ment, which act upon the neutrophils to increase their viscoelasticity and promote the interaction of neutrophil cell adhesion molecules wit h counter ligands on the endothelial cell, are the primary factors reg ulating the size of the pulmonary pool of vascular neutrophils. 4. The primary afferent nerves, through their release of substance P, are th e most important neural elements regulating neutrophil accumulation an d function. Substance P facilitates the actions of other inflammatory agents (e.g. LTB4, platelet activating factor) on neutrophil adhesion, migration and biochemical reactivity. 5. The sympathetic nervous syst em indirectly regulates neutrophil functions by regulating the release of an immunosuppressive factor from submandibular glands. 6. With con tinued study of nervous system regulation of neutrophil function, the mechanisms by which psychological factors affect these cells will even tually be revealed.