Increased number of immunoreactive nerve fibers in atopic dermatitis.

The presence of immunologic markers for neurofilaments, neuropeptides of sensory nerve fibers (Calcitonin gene-related peptide and substance P), for noradrenergic innervation (neuropeptide Y and Tyrosine hydroxylase), and Neuron-specific protein 9.5 was evaluated in frozen tissue sections from normal skin (n = 34) and from skin biopsies manifesting urticaria (n = 6), leukocytoclastic vasculitis (n = 4), systemic lupus erythematosus (n = 23), and atopic dermatitis (n = 40, of which 16 were from lesions induced by epicutaneous atopic allergen patch tests). In some normal skin specimens immunoreactive nerve fibers expressing Neuron-specific protein 9.5 were observed in the epidermis, dermis, and around blood vessels. For the other markers, immunolabeling was mainly observed in the dermis around blood vessels. Neurofilaments, which are scarce in normal skin epidermis, were present in higher density in the epidermis of affected skin in all disease conditions. Biopsies from urticaria and systemic lupus erythematosus showed a decrease in density of fibers immunolabeled for neuropeptides substance P and Calcitonin gene-related peptide and for Neuropeptide Y. In biopsies from skin with atopic dermatitis, an increased density of fibers was observed for all markers except Neuropeptide Y and Tyrosine hydroxylase. In this group, biopsies from positive atopic allergen patch tests showed an enhanced density of fibers labeled by antibody to Neuron-specific protein 9.5 and a lower density in labeling for Tyrosine hydroxylase. The data indicate a potential role of innervation and neuropeptides in dermatoses like atopic dermatitis.