Immune System Practice Test

Immune cells communicate with one another through signaling molecules called cytokines. These proteins are released by various immune cells in response to infection or injury and travel to target cells by binding to specific receptors. The result is coordinated actions across the immune system—activating cells, promoting or limiting inflammation, guiding cell growth and differentiation, and helping recruit cells to sites of infection. Cytokines include many different types, such as interleukins, interferons, and tumor necrosis factors. Chemokines are a subset of cytokines whose main job is to direct cell movement toward areas of infection (chemotaxis), so they’re still part of the broader cytokine family. Antibodies, while crucial for recognizing and neutralizing pathogens, are not the signaling messages used for communication between immune cells. Hormones act as endocrine signals in the body and are not the primary means of immune-cell communication.