Immune Reactions in Contact Dermatitis Affected Skin

Allergic contact dermatitis is a term for a skin reaction resulting from exposure to specific substances that come into contact with skin that is hypersensitive (allergic) to the substance. These substances are called "allergens." Some common allergens are nickel, rubber, dyes, poison ivy, poison oak and other related plants. These allergens do not cause a skin reaction in most individuals, but for some, once the skin becomes sensitive or allergic to the substance, any exposure to that specific allergen will produce a rash that may consist of redness, swelling and blisters. This rash may become worse with each exposure to the allergen. The skin reaction results from two phases. In the induction phase, initial exposure to the allergen occurs. The body recognizes the allergen as foreign and the immune system, which is the body's primary line of defense against infections and other things perceived as foreign to the body, mounts an immune response against the body, itself. During this immune response, cells specific to the allergen are activated. In the second phase, the elicitation phase, the skin is again exposed to the allergen and an immune response occurs, as the cells that are specific to the allergen attack the skin, leading to the rash. In order to diagnose allergic contact dermatitis, a clinician will discuss the materials that touch the patient's skin at work and home and perform patch tests. In a patch test, a very small amount of the suspected allergens are applied to the skin for a fixed time. After that designated time, the clinician will determine whether a reaction has occurred to the applied allergens. Currently, the main treatment for allergic contact dermatitis is avoidance of the allergen.

This study hopes to improve our understanding of how the immune system acts in allergic contact dermatitis. In order to reach this goal, normal volunteers, who are suspected of having allergic contact dermatitis, will be patch tested for the fifteen most common allergens. Then, biopsies will be taken of the skin at the sites where the there is a positive reaction to the allergen. Also, small biopsies will be taken from an area that received a patch but no allergen and an area that did not receive a patch to serve as controls. In a second stage of the study, volunteers will receive patches with the allergen to which they demonstrated an allergic response. More biopsies will be taken, over three designated time points. The biopsied skin samples will then be studied in a laboratory by methods such as immunohistochemistry and microarray analysis, which will help define the progression of the immune reaction in allergic contact dermatitis. The rationale for the study is to better understand how the immune system is activated to produce the rash of allergic contact dermatitis, so that treatments can target the cells that are involved in the activation.