Which type of sensitization is primarily involved in allergic dermatitis?

Allergic dermatitis primarily involves cell-mediated hypersensitivity, specifically Type IV hypersensitivity, which is an immune response that is mediated by T cells rather than antibodies. This type of reaction occurs when allergens penetrate the skin and are processed by antigen-presenting cells, leading to the activation of T lymphocytes. These T cells then release cytokines that promote inflammation and recruit other immune cells to the site of exposure, resulting in the symptoms characteristic of allergic dermatitis, such as redness, itching, and swelling.

This immune response is distinct from IgE-mediated hypersensitivity, which primarily involves immediate reactions like anaphylaxis or allergic rhinitis. In contrast, Type IV hypersensitivity reactions typically take hours to days to manifest. Antibody-mediated hypersensitivity involves different mechanisms such as the activation of the complement system, and autoimmune hypersensitivity relates to conditions where the immune system mistakenly attacks self-tissues. All of these mechanisms are distinct from the T cell-mediated pathway involved in allergic dermatitis.