Which cells release chemicals such as histamine that promote inflammation?

• A. Neutrophils
• B. Basophils
• C. Eosinophils
• D. Mast cells

Answer: (D)

Histamine release to promote inflammation comes mainly from tissue-resident mast cells. These cells lie in connective tissue near blood vessels and mucosal surfaces, ready to respond when they encounter allergens or injury. When activated, mast cells rupture their granules and release histamine along with other mediators, causing vasodilation and increased vascular permeability. That makes the area red, swollen, and allows immune cells to access the site more easily, which is the hallmark of inflammation.

Basophils can also release histamine, but they circulate in the blood rather than reside in tissues, so mast cells are the primary drivers of local inflammatory histamine release. Neutrophils and eosinophils have other roles in immunity and inflammation and aren’t the main sources of histamine.