Dual effects of CGRP-antagonist on allergic contact dermatitis in human skin

There is increasing evidence of an interaction between the nervous and the immune systems. The aim of this study was to investigate the rôle of calcitonin gene-related peptide (CGRP) in the modulation of the elicitation of immediate and delayed, immunological and non-immunological reactions in human skin. CGRP (13 pmol and 39 pmol), and the CGRP-antagonist, CGRP/8-37/, (50 pmol and 500 pmol) were injected intracutaneously prior to provocation tests. Patients with allergy to nickel were provoked with nickel sulfate epicutaneously, and the reactions were evaluated by a clinical scoring system (guidelines of the International Contact Dermatitis Research Group). Patients with allergy to birch pollen were provoked by a prick test with the allergen, and the volume of the weals was measured. The patients were also provoked with tuberculin (delayed immunologic reaction), benzalkonium chloride (irritant contact dermatitis), UV-light and benzoic acid (non-immunologic contact urticaria). The test reactions were estimated by planimetry. CGRP/8-37/ exerted dual effects on allergic contact dermatitis, causing potentiation at a dose of 500 pmol (p= 0.004) and inhibition at a dose of 50 pmol (p=0.012). Other reactions were not significantly affected by the pretreatments. The results suggest that CGRP participates in delayed inflammatory reactions, but is not involved in immediate immunologic reactions.