Metal-derivatized Major Histocompatibility Complex : Zeroing in on Contact Hypersensitivity

One of the prices we pay for our love of jewelry is allergic contact hypersensitivity to metal, an autoimmune condition that variably afflicts around 10% of all Caucasians (1). Contact hypersensitivity is a classic type IV DTH (delayed type hypersensitivity) response, involving primed T cells that are specific for metal modified antigens generated at a local site in the body (most commonly the epidermal layer of the skin). The T cells respond by producing proinflammatory mediators that result in local redness, swelling, and itching (2). In many cases nickel is found to be the culprit and unfortunately for sensitive people, nickel is one of the most common metals in the environment, which makes it particularly difficult to avoid. Being a ubiquitous component of metal alloys, nickel is found not only in catheters, needles, dental braces, and many other medical devices, but...