Cytokines are primarily produced by which cells?

• A. Mast cells
• B. T lymphocytes & macrophages
• C. Neutrophils
• D. Epithelial cells

Answer: (B)

Cytokines are signaling proteins that coordinate immune responses, and the primary sources of these signaling molecules are activated T lymphocytes and macrophages. T cells release cytokines such as IL-2 to promote their own proliferation and IFN-γ to activate macrophages, while macrophages produce IL-1, IL-6, and TNF-α to drive inflammation and recruit other immune cells. This combination is central to orchestrating immune signaling, making T lymphocytes and macrophages the chief producers.

Mast cells do release cytokines, but their hallmark functions are releasing preformed mediators like histamine, which drive allergic and immediate hypersensitivity responses. Neutrophils can secrete cytokines, yet they are more renowned for rapid phagocytosis and short-term antimicrobial actions rather than being the main cytokine producers. Epithelial cells can also produce cytokines in inflamed tissues, but the dominant, coordinating cytokine sources in most immune responses are the T lymphocytes and macrophages.