Cytokine
A broad category of small signalling proteins released by immune cells that regulate inflammation, immunity, and cell communication. Cytokines include interleukins, interferons, and tumour necrosis factors. Excessive cytokine release (cytokine storm) can be a serious complication of immune-modulating therapies.
Technical Context
Major cytokine categories: interleukins (IL-1 through IL-40+ — diverse immune regulatory functions), interferons (IFN-α/β — type I, antiviral; IFN-γ — type II, macrophage activation and Th1 immunity), tumour necrosis factors (TNF-α, lymphotoxin), colony-stimulating factors (G-CSF, GM-CSF, M-CSF — haematopoiesis), chemokines (approximately 50 members — directing cell migration), and transforming growth factors (TGF-β — immunosuppressive, pro-fibrotic). Cytokine signalling: most cytokines signal through JAK-STAT pathway (receptor-associated JAK kinases phosphorylate STAT transcription factors → nuclear translocation → gene regulation). Cytokine storm (systemic inflammatory response from excessive cytokine release — potentially fatal) can occur with immune-activating therapies. For peptide drugs: corticotropin stimulates cortisol which broadly suppresses cytokine production; glatiramer acetate shifts cytokine profiles from Th1 (pro-inflammatory) to Th2 (anti-inflammatory); and thymosin alpha-1 modulates cytokine production by dendritic cells.