Immunohistochemical characterization of HSP, alpha-MSH, Merkel cells and neuronal markers in acute UV dermatitis and acute contact dermatitis in vivo

Objective: To study the immunoneurocrine network in inflammatory dermatoses, we investigated histochemically acute UV and acute contact dermatitis. Methods: Antibodies were applied to frozen and paraffin specimens of human skin after irradiation (n = 10), to positive patch tests (n = 10) and controls (n = 10) against: HSP 70, 72, 27, neuronal polypeptides (a-MSH: NSE, bombesin, PGP 9.5, NGF, NGF-R) and intermediate filaments (peripherin, NF 200, CK 19, 20). Results: HSPs and alpha-MSH were upregulated in UV dermatitis in the epidermis compared to contact dermatitis and normal skin. Sunburn cells did not express HSPs or alpha-MSH in UV dermatitis. Neuronal markers and HSP 27 labeled more nerve fibers in UV than in contact dermatitis, except the increased staining for NGF, NGF-R and alpha-MSH in nerve fibers in contact dermatitis. In UV dermatitis, 50% of Merkel cells were suprabasal, but in contact dermatitis, basal, rounded and reduced in number. Conclusions: Merkel cells, HSPs and markers of neuroinflammation are of different importance in UV and contact dermatitis in vivo.