What are cytokines in the immune system?

Cytokines are indeed signaling molecules that play a crucial role in mediating and regulating immune responses. They are proteins released by various cells in the immune system, including lymphocytes and macrophages, and they function as communication tools between cells. By binding to specific receptors on the surface of other immune cells, cytokines can enhance or suppress the immune response. They help coordinate the overall immune reaction by influencing the behavior of immune cells, such as promoting cell growth, differentiation, and activation.

In the context of the immune system, cytokines can initiate responses to pathogens and regulate inflammation, among other functions. This regulation is vital for maintaining homeostasis and ensuring that the immune response is appropriately balanced, avoiding excessive inflammation or immune dysfunction.

Other options describe different components of the immune system but do not accurately define cytokines. Pathogens refer to the organisms that provoke immune responses, while cells that engulf and digest foreign substances are typically phagocytes. Antibodies represent a distinct aspect of the immune response, produced by B cells to specifically target pathogens, rather than acting as signaling molecules like cytokines.