Interleukins are which type of signaling molecule and are primarily produced by which cells?

• A. Enzyme produced by liver for metabolism
• B. Protein (cytokine) primarily produced by T cells, active in inflammatory and immune responses and leukocyte communication
• C. Hormone produced by pancreas
• D. Antibody produced by B cells

Answer: (B)

Interleukins are signaling molecules in the immune system; they are cytokines, meaning they are proteins that act as messages between immune cells. They help coordinate inflammation, activate and differentiate immune cells, and direct leukocyte traffic during an immune response. Helper T cells are a primary source of these signals, and their release of interleukins modulates how other immune cells respond to infection or injury. This is why the correct description is a protein (cytokine) produced by T cells, active in inflammatory and immune responses and leukocyte communication. They are not enzymes from the liver, hormones from the pancreas, or antibodies produced by B cells.