Which dermal cell type is most associated with allergic responses and inflammation?

• A. Fibroblast Cells
• B. Leucocytes
• C. Histiocytes
• D. Mast Cells

Answer: (D)

Allergic reactions in the skin are driven by mast cells. These cells live in the dermal connective tissue and carry IgE antibodies on their surface. When an allergen binds to those IgE molecules, the mast cells degranulate, releasing histamine and other mediators. Histamine causes rapid changes: dilation of small blood vessels, increased vascular permeability, itching, redness, and swelling—classic signs of inflammation in an allergic response. That immediate, IgE-triggered degranulation is what links mast cells most directly to allergic inflammation in the skin.

Fibroblasts keep the tissue structure, making collagen and supporting the extracellular matrix. Leucocytes are a broad group of white blood cells involved in many inflammatory responses but aren’t the primary drivers of immediate allergic reactions in the skin. Histiocytes are tissue macrophages involved in cleaning up debris and presenting antigens; they participate in inflammation but not in the rapid histamine-mediated allergic response described above.