Which cells release histamine and promote inflammation?

• A. Osteoclasts
• B. Melanocytes
• C. Fibroblasts
• D. Mast cells

Answer: (D)

The main concept here is identifying which cells release histamine to drive inflammation. Mast cells reside in connective tissue near blood vessels and, when activated (such as during injury or exposure to allergens), they degranulate and release histamine along with other mediators. Histamine causes the blood vessels to dilate and become more permeable, leading to redness, swelling, warmth, and itchiness—classic signs of inflammation. The cells listed have different primary roles: osteoclasts break down bone tissue, melanocytes produce pigment in the skin, and fibroblasts synthesize extracellular matrix and collagen for tissue repair. None of these primarily release histamine to promote inflammation in the same way mast cells do.