cytokín

Cytokin, or cytokines, are a broad and diverse group of small secreted proteins that act as signaling molecules between cells, especially within the immune system. They are produced by a wide range of cells, including macrophages, T cells, dendritic cells, endothelial cells, and fibroblasts, in response to infection, injury, or other stimuli. Cytokins exert their effects by binding to specific receptors on target cells, triggering intracellular signaling cascades such as JAK-STAT, MAPK, and NF-kB pathways, which regulate gene expression and cellular behavior.

Cytokin are classified into several families, including interleukins, interferons, chemokines, tumor necrosis factors, growth factors, and colony-stimulating factors. They can act in autocrine, paracrine, or endocrine manners and often display pleiotropy, redundancy, synergism, or antagonism. Their effects depend on the context, concentration, and receptor expression on target cells.

Functions include coordinating immune responses to infection, shaping inflammation, and promoting tissue repair and hematopoiesis. Dysregulation or excessive production can contribute to disease, such as autoimmune disorders, chronic inflammatory diseases, sepsis, or cytokine storms, and may influence cancer progression.

Therapeutic and clinical relevance: cytokine pathways are targets for drugs (for example, TNF inhibitors and IL-6 receptor blockers) and, in some cases, cytokines themselves are used as therapies (such as interferons or interleukins in cancer or viral infections). Cytokine levels can serve as biomarkers, though their short half-lives and dynamic regulation complicate interpretation.