Important Cytokines

Secreted by macrophages

Interleukin-1 Causes fever, acute inflammation.

Activates endothelium to express adhesion molecules.

Induces chemokine secretion to recruit WBCs.

Also known as osteoclast-activating factor.

Induces VEGF expression.

IL-1β contributes to cancer cachexia

Activates naïve TH0 lymphocytes to differentiate into Th1 & Th2.


“Hot T-bone stEAK”:

IL-1: fever (hot).

IL-2: stimulates T cells.

IL-3: stimulates bone marrow.

IL-4: stimulates IgE production.

IL-5: stimulates IgA production.

IL-6: stimulates aKute-phase protein


Interleukin-12 Induces differentiation of T cells into Th1 cells.

Activates NK cells.

Interleukin-6 Causes fever and stimulates production of acute phase proteins → ­ ESR

Contributes to cancer cachexia

Interleukin-8 Major chemotactic factor for neutrophils. “Clean up on aisle 8.” Neutrophils are recruited by IL-8 to clear infections.
Tumor necrosis factor-α Secreted by macrophages and T-cells

Activates endothelium.

Causes WBC recruitment, vascular leak, fever, acute phase reactions (CRP, fibrinogen).

Regulates apoptosis.

Increases basal metabolic rate.



Causes cachexia in malignancy.

Maintains granulomas in TB.

Induces insulin resistance through activation of serine kinases, which phosphorylate serine residues on insulin receptors, inhibiting tyrosine phosphorylation.

IL-1, IL-6, TNF-α can mediate fever and sepsis.


Secreted by all T cells

Interleukin-2 Stimulates growth of helper, cytotoxic, and regulatory T cells, B cells, and NK cells.
Interleukin-3 Activated by CD4+ Th cells.

Supports growth and differentiation of bone marrow myeloid stem cells. Functions like GM-CSF.


From Th1 cells, NK Cells

Interferon-γ Secreted in response to antigen or IL-12 from macrophages dimerization of the receptor & activation of Janus kinase 1 & 2 nuclear signaling via STAT1 & transcription of IFN-gamma-regulated genes stimulates macrophages to kill phagocytosed pathogens.

Inhibits differentiation of Th2 cells.

Also activates NK cells to kill virus-infected cells.

Stimulates CD8+ cytotoxic T-cells (together with IL-2)

Increases MHC expression and antigen presentation by all cells.

Induces VEGF expression.


From Th2 cells

Interleukin-4 Induces differentiation of T cells into Th (helper) 2 cells.

Promotes growth of B cells.

Enhances class switching to IgE and IgG.

Ain’t too proud 2 BEG 4 help.
Interleukin-5 Promotes growth and differentiation of B cells and eosinophils. Enhances class switching to IgA.  
Interleukin-10 Attenuates inflammatory response. Decreases expression of MHC class II and Th1 cytokines (by inhibiting interferon gamma synthesis, leading to decreased Th1 cells). Inhibits activated macrophages and dendritic cells. Also secreted by regulatory T cells. TGF-β and IL-10 both attenuate the immune response.


From Treg cells, platelets, macrophages, endothelial cells, smooth muscle cells, fibroblasts & keratinocytes

TGF-ß Decreases T cell proliferation and cytokine production. Involved in tissue regeneration & repair.

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