DENSITY AND FINE-STRUCTURE OF PERIPHERAL-NERVES IN VARIOUS SKIN-LESIONS OF ATOPIC-DERMATITIS

The density and fine structure of the peripheral nerve system in vario us skin lesions of 64 patients with atopic dermatitis (AD) was quantit atively analyzed by immunohistochemical staining with antibodies direc ted against protein gene product (PGP) and substance P (SP). The densi ty of PGP-positive peripheral nerves was 2.5 x 10(3) mu m(2)/Delta s ( Delta s = 0.24 mm(2) selected area) in early acute lesions, 3.8 x 10(3 ) mu m(2)/Delta s in subacute lesions, 4.9 x 10(3) mu m(2)/Delta s in lichenified lesions and 7.1 x 10(3) mu m(2)/Delta s in prurigo lesions of AD. The density of nerve fibers in subacute, lichenified and pruri go lesions was significantly higher than in uninvolved skin of AD pati ents (2.0 x 10(3) mu m(2)/Delta s). Electron microscopically, bulging of axons with many mitochondria and a loss of their surrounding sheath of Schwann cells suggests that the free nerve endings in skin lesions of AD are in an active state of excitation. Many pinocytotic vesicles in the periphery of basal keratinocytes facing nerve endings which co ntained many neurovesicles suggests reciprocal effects between keratin ocytes and nerve endings. The number of SP-positive nerve fibers in AD lesions was far less than one-tenth of the number of PGP-positive ner ve fibers.