The possible role of Nickel in the pathogenesis of contact allergic dermatitis, immune dysregulation and Systemic Nickel Allergy Syndrome

nickel (ni) represents the principal hapten involved in the determinism of allergic contact dermatitis (aCD). Many studies have demonstrated a role of nickel in the dysregulation of the immune system and in the pathogenesis of the systemic manifestations of the allergy. ni is the most common contact allergen in both professional and non-professional fields because it is commonly present in metal objects, colorants for porcelain, glass, pottery, detergents and food. It is known that ni-aCD has a high prevalence in the general population. the exposure to ni can occur not only through the contact with the skin but also by the gastrointestinal absorption. the ni allergy was associated to immune dysregulation with prevalent immunosuppressive action, gastrointestinal symptoms, cutaneous manifestations, recurrent infections and increase in oxidative stress. the extracutaneous and cutaneous manifestations in areas not in contact with ni are the principal manifestations of the Systemic nickel allergy Syndrome. nevertheless the data of literature don’t consent to reach definitive conclusions. In this review we want to clarify the potential immunomodulatory action of nickel and the possible clinical manifestations of the allergy.