What is the function of IL-8?

• A. Chemotactic factor for recruitment of neutrophils
• B. Stimulates antibody production
• C. Inhibits leukocyte recruitment
• D. Activates eosinophils

Answer: (A)

IL-8 is a chemokine whose primary role is to recruit neutrophils to sites of infection or injury. It creates a chemical gradient that guides neutrophils from the bloodstream into inflamed tissue and activates them to adhere, migrate, and release microbicidal substances. This chemotactic signal is produced by cells like macrophages, endothelial, and epithelial cells in response to pro-inflammatory signals such as IL-1 and TNF.

It does not drive antibody production, which is a B cell–mediated process influenced by other cytokines (like IL-4, IL-5, IL-6). It also does not inhibit leukocyte recruitment, nor is it the main activator of eosinophils (which are more driven by IL-5 and eosinophil-specific chemokines like eotaxin). So the best description is that IL-8 acts as a chemotactic factor for recruitment of neutrophils.