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How does interleukin-1 contribute to fever?

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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.

Interleukin-1 (IL-1) contributes to fever by acting as a pyrogen, a chemical substance that triggers an elevation in body temperature.1

When the body encounters infectious agents such as bacteria or viruses, the immune system produces specific cytokines, including IL-1, to mediate the inflammatory response. These pyrogens travel through the bloodstream to the hypothalamus, the region of the brain responsible for regulating body temperature.12

Upon reaching the hypothalamus, IL-1 and other pyrogens disturb its normal functioning by inhibiting heat-sensing neurons and exciting cold-sensing ones. This process effectively deceives the hypothalamus into perceiving the body as cooler than it actually is. In response, the hypothalamus raises the body's temperature set point, resulting in a fever. This physiological reaction is considered a defensive mechanism, as the increased temperature helps stimulate white blood cell activity and antibody production while potentially inhibiting the growth of certain pathogens.1