🧬 Cytokines are small proteins released by cells that regulate immune responses, inflammation, and hematopoiesis.
They act in autocrine 🔄, paracrine 📡, or endocrine 🩸 fashions to influence cell behaviour.
🌟 Types of Cytokines
- 🧪 Interleukins (ILs) :
- Produced mainly by leukocytes 🦠 → act on other leukocytes.
- Roles: activation, proliferation, differentiation, migration.
- Examples:
- 🔥 IL-1: Promotes inflammation & fever.
- 💪 IL-2: Stimulates T-cell proliferation.
- 🩸 IL-6: Inflammation + hematopoiesis.
- 🛑 IL-10: Anti-inflammatory regulator.
- 💥 Tumour Necrosis Factors (TNFs) :
- Produced by macrophages + T cells.
- Key in inflammation + apoptosis ☠️.
- Examples:
- 🔥 TNF-α: Drives inflammation & apoptosis.
- 🧩 TNF-β: Immune regulation & lymphoid development.
- 🛡️ Interferons (IFNs) :
- Produced in response to viral infections 🦠.
- Antiviral, antitumour, immunomodulatory.
- Examples:
- 🦠 IFN-α & IFN-β: Antiviral defence.
- ⚔️ IFN-γ: Activates macrophages + boosts antigen presentation.
- 🧭 Chemokines :
- Guide immune cell migration 🚶♂️.
- Examples:
- 🎯 CCL2 (MCP-1): Recruits monocytes + T cells.
- 🚑 CXCL8 (IL-8): Attracts neutrophils.
- 🩸 Colony-Stimulating Factors (CSFs) :
- Stimulate hematopoiesis in bone marrow.
- Examples:
- 🔵 G-CSF: Granulocytes (esp. neutrophils).
- 🟠 GM-CSF: Granulocytes + macrophages.
- 🌱 Growth Factors :
- Control cell growth & repair.
- Examples:
- 🛠️ TGF-β: Immune regulation + tissue repair.
- 🌿 EGF: Stimulates cell proliferation.
⚙️ Functions of Cytokines
- 🧩 Immune regulation: balance between humoral & cell-mediated immunity.
- 🔥 Inflammation: recruit leukocytes; IL-1 & TNF-α vs. IL-10.
- 🩸 Hematopoiesis: CSFs drive blood cell production.
- 🌱 Cell growth & differentiation: guided by growth factors.
- 🦠 Antiviral defence: IFNs inhibit viral replication.
- ☠️ Apoptosis: TNF induces programmed cell death.
🏥 Clinical Relevance
- ♻️ Autoimmunity: e.g., RA, MS, SLE → cytokine imbalance; TNF inhibitors used therapeutically.
- 🔥 Chronic inflammation: e.g., IBD, psoriasis.
- ⚠️ Infections: Cytokine storms in sepsis, COVID-19.
- 🎗️ Cancer: IL-2 & IFN-α used as immunotherapy agents.
- 🤧 Allergy & asthma: IL-4, IL-5 drive IgE + eosinophil activation.
📌 Summary
🧬 Cytokines are essential signalling proteins that coordinate immunity, inflammation, blood cell production, and tissue repair.
⚖️ They act in complex networks, and dysregulation underlies many diseases → making them key drug targets in modern medicine.
