𧬠Cytokines are small proteins released by cells that regulate immune responses, inflammation, and hematopoiesis.
They act in autocrine π, paracrine π‘, or endocrine π©Έ fashions to influence cell behaviour.
π Types of Cytokines
- π§ͺ Interleukins (ILs) :
- Produced mainly by leukocytes π¦ β act on other leukocytes.
- Roles: activation, proliferation, differentiation, migration.
- Examples:
- π₯ IL-1: Promotes inflammation & fever.
- πͺ IL-2: Stimulates T-cell proliferation.
- π©Έ IL-6: Inflammation + hematopoiesis.
- π IL-10: Anti-inflammatory regulator.
- π₯ Tumour Necrosis Factors (TNFs) :
- Produced by macrophages + T cells.
- Key in inflammation + apoptosis β οΈ.
- Examples:
- π₯ TNF-Ξ±: Drives inflammation & apoptosis.
- π§© TNF-Ξ²: Immune regulation & lymphoid development.
- π‘οΈ Interferons (IFNs) :
- Produced in response to viral infections π¦ .
- Antiviral, antitumour, immunomodulatory.
- Examples:
- π¦ IFN-Ξ± & IFN-Ξ²: Antiviral defence.
- βοΈ IFN-Ξ³: Activates macrophages + boosts antigen presentation.
- π§ Chemokines :
- Guide immune cell migration πΆββοΈ.
- Examples:
- π― CCL2 (MCP-1): Recruits monocytes + T cells.
- π CXCL8 (IL-8): Attracts neutrophils.
- π©Έ Colony-Stimulating Factors (CSFs) :
- Stimulate hematopoiesis in bone marrow.
- Examples:
- π΅ G-CSF: Granulocytes (esp. neutrophils).
- π GM-CSF: Granulocytes + macrophages.
- π± Growth Factors :
- Control cell growth & repair.
- Examples:
- π οΈ TGF-Ξ²: Immune regulation + tissue repair.
- πΏ EGF: Stimulates cell proliferation.
βοΈ Functions of Cytokines
- π§© Immune regulation: balance between humoral & cell-mediated immunity.
- π₯ Inflammation: recruit leukocytes; IL-1 & TNF-Ξ± vs. IL-10.
- π©Έ Hematopoiesis: CSFs drive blood cell production.
- π± Cell growth & differentiation: guided by growth factors.
- π¦ Antiviral defence: IFNs inhibit viral replication.
- β οΈ Apoptosis: TNF induces programmed cell death.
π₯ Clinical Relevance
- β»οΈ Autoimmunity: e.g., RA, MS, SLE β cytokine imbalance; TNF inhibitors used therapeutically.
- π₯ Chronic inflammation: e.g., IBD, psoriasis.
- β οΈ Infections: Cytokine storms in sepsis, COVID-19.
- ποΈ Cancer: IL-2 & IFN-Ξ± used as immunotherapy agents.
- π€§ Allergy & asthma: IL-4, IL-5 drive IgE + eosinophil activation.
π Summary
𧬠Cytokines are essential signalling proteins that coordinate immunity, inflammation, blood cell production, and tissue repair.
βοΈ They act in complex networks, and dysregulation underlies many diseases β making them key drug targets in modern medicine.