Which type of hypersensitivity is associated with contact dermatitis?

Prepare for the NBEO Systemic Disease Exam. Use flashcards and multiple-choice questions to test your knowledge. Each question includes hints and explanations. Enhance your understanding and readiness for the exam.

Contact dermatitis is primarily associated with Type 4 hypersensitivity, also known as delayed-type hypersensitivity. This reaction involves T-cell mediated immune responses rather than antibody-mediated mechanisms. In the case of contact dermatitis, substances such as poison ivy or certain metals trigger an immune reaction after the skin comes into direct contact with these allergens.

Upon first exposure to an allergen, skin-associated dendritic cells capture the allergen and present it to naïve T cells in the lymph nodes. This primes the T cells and leads to the development of memory T cells specific to that allergen. Upon subsequent exposures, these memory T cells rapidly respond, activating immune cells and leading to inflammation and skin damage, which manifests as the symptoms of contact dermatitis.

This mechanism distinctly differentiates Type 4 hypersensitivity from the other types, which involve different immune responses. For instance, Type 1 hypersensitivity is characterized by IgE-mediated reactions, such as allergies to pollen. Type 2 hypersensitivity involves IgG or IgM antibodies against cell surface or matrix antigens, resulting in cell destruction. Type 3 hypersensitivity is associated with immune complex deposition, leading to inflammation and tissue damage. These mechanisms are not the primary processes involved in contact dermatitis, reinforcing why Type 4

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