The immunomodulatory effect of nerve growth factor

A prolonged application of nerve growth factor (NGF) to neonatal prepuberal rats induced selective hypertrophy and hyperfunction of ganglionic sympathetic neurons. This was accompanied by higher density and fluorescence intensity of varicose adrenergic fibers and terminals in the immunocompetent organs, total increase of catecholamines in them, catecholamine diffusion into the intercellular space, and their accumulation by macrophages and mast cells. The plaque-forming and lymphocyte blast transformation responses were activated, signs of increased lymphocyte migration to peripheral lymphoid tissues appeared, and histamine concentration in the thymus and spleen increased. All of the foregoing indicate the immunomodulatory effect of NGF and the dependence of immune responsiveness of the organism on the functional state of the adrenergic moiety. The net effect of the increase is attributed to non-specific protein sensitization, changes in the sympathetic (and, probably, somatic) nervous system, and direct action on immunocompetent cells.