What is the main immunological process that mediates allergic contact dermatitis?

Allergic contact dermatitis is primarily mediated by T cells, specifically through a type of delayed-type hypersensitivity reaction. This immunological process involves sensitization to a specific allergen that penetrates the skin. Upon first exposure, dendritic cells capture and process the allergen, presenting it to naïve T cells in the lymph nodes. This interaction leads to the activation and proliferation of CD4+ T helper cells and CD8+ cytotoxic T cells, which then migrate back to the skin.

Upon re-exposure to the same allergen, these primed T cells mount an immune response that results in inflammation and the clinical manifestations of allergic contact dermatitis, such as erythema, vesiculation, and pruritus. The involvement of macrophages further amplifies the immune response in the affected area and contributes to tissue damage.

In contrast, the other immunological processes mentioned do not play a direct role in allergic contact dermatitis. B-cell and antibody-mediated responses are more characteristic of immediate hypersensitivity reactions, such as those seen in allergic rhinitis or anaphylaxis. Complement-mediated processes and neutrophil-mediated responses are generally associated with other types of immune reactions, like infection or autoimmune conditions, rather than the specific delayed hypersensitivity seen in allergic contact