Review article Series V. The skin as target for IgE-mediated allergic reactions - Immunologic mechanisms in hypersensitivity reactions to metal ions:an overview

Metal ions such as Ni2+, Co2+, Cu2+, or Cr3+ are haptens with a high immuno genic potential, as contact dermatitis caused by ionic metals occurs in abo ut 10-15% of the human population. Since alloys containing Ni2+, Co2+, and Cr3+ are components of implants in replacement surgery, dentures, orthodont ic wires, and various other devices, adverse reactions to metal ions create serious problems in practical medicine as incompatibility reactions to met al-containing biomaterials. On the other hand, contact dermatitis to metal ions such as Ni2+ is a well-established model for studying the molecular me chanisms involved in the recognition of haptens by the immune system. Altho ugh many investigations have been performed to elucidate the molecular inte ractions causing contact hypersensitivity in man, many aspects remain to be clarified. This review will focus on the experimental data accumulated so far on the immunologic mechanisms responsible for the recognition of metal ions by T cells and eliciting adverse immune reactions causing contact derm atitis.