Cytokine

Small signaling proteins released by cells that regulate immunity, inflammation, and hematopoiesis. Key cytokine families include interleukins (ILs), tumor necrosis factors (TNFs), interferons (IFNs), and chemokines. Cytokines can be pro-inflammatory (IL-6, TNF-alpha) or anti-inflammatory (IL-10, TGF-beta). Research into immunomodulatory peptides frequently measures cytokine levels as endpoints, as they provide direct evidence of immune system modulation.