What type of cells in the dermis are involved in allergic reactions?

• A. Mast cells
• B. Fibroblasts
• C. Keratinocytes
• D. Langerhans cells

Answer: (A)

Mast cells in the dermis are pivotal in allergic reactions due to their role in the immune response. These cells are equipped with granules that contain histamine and other inflammatory mediators. When an allergen is encountered, mast cells degranulate, releasing these substances into the surrounding tissue. This release leads to the typical symptoms of an allergic reaction, such as inflammation, redness, and swelling.

In contrast, fibroblasts, while crucial for the structural integrity and collagen production in the dermis, do not participate directly in immune responses, including allergic reactions. Keratinocytes, the predominant cells in the epidermis, primarily serve a protective function and are also not directly involved in the immune response to allergens. Langerhans cells play a role in immune surveillance and antigen presentation, but they are not the primary mediators of allergic reactions the way mast cells are. Understanding the specific functions of these various cell types clarifies why mast cells are central to the process of mediating allergic responses in the skin.