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How do interleukins help immune cells communicate?

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Immune stimulation by activated helper T cells — immune system Stimulation of immune response by activated helper T cells. Activated by complex interaction with molecules on the surface of a macrophage or some other antigen-presenting cell, a helper T cell proliferates into two general subtypes, T_H1 and T_H2. These in turn stimulate the complex pathways of the cell-mediated immune response and the humoral immune response, respectively.

Interleukins are a group of naturally occurring proteins that function as cytokines, acting as chemical messengers to facilitate communication between cells. Rather than being stored, they are synthesized and secreted rapidly in response to stimuli, such as the presence of an infectious agent.12

Once secreted, an interleukin travels to a target cell and binds to a specific receptor on the cell's surface. This binding event triggers a signaling cascade within the target cell, which ultimately alters the cell's behavior by influencing gene transcription and protein expression.12

In the context of the immune system, interleukins coordinate complex responses by regulating the growth, differentiation, and activity of various leukocytes. For example, they help activate T and B lymphocytes, mediate inflammation, and stimulate the production of antibodies. By determining which cells respond to a specific infection, interleukins ensure that the immune system mounts an appropriate and effective defense.123