Important Cytokines Flashcards
IL-1
“Hot T-Bone stEAk”
Secreted by macrophages. An endogenous pyrogen, causes fever, acute inflammation. Activates endothelium to express adhesion molecules; induces chemokine secretion to recruit leukocytes.
IL-2
“Hot T-Bone stEAk”
Secreted by all T cells. Stimulates the growth of helper, cytotoxic, and regulatory T-cells. Many immunosuppressents work by inhibiting IL-2:
- Cyclosporine (Nephrotoxic): Binds to cyclophilins, forming a complex that inhibits calcineurin which normally activates IL-2 production. No IL-2 = no T cell differentiation and activation
- Tacrolimus (Nephrotoxic): Binds to FK-binding protein, inhibiting calcineurin, resulting in the same effect as Cyclosporine
- Sirolimus: Binds FKBP-12 which inhibits mTOR. This inhibits the cell’s response to IL-2, resulting in the same effects as above
IL-3
“Hot T-Bone stEAk”
Secreted by all T cells. Supports growth and differentiation of bone marrow stem cells. Functions like GM-CSF
IL-4
“Hot T-Bone stEAk”
Secreted by Th2 cells. Induces differentiation into Th2 cells. Promotes growth of B cells. Enhances class switching to IgE and IgG
IL-5
“Hot T-Bone stEAk”
Secreted by Th2 cells. Promotes differentiation into Th2 cells. Promotes growth of B cells. Enhances class switching to IgA. Stimulates growth and differentiation of eosinophils.
IL-6
Secreted by macrophages and Th2 cells. An endogenous pyrogen. Causes fever and stimulates production of acute-phase proteins
IL-8 (CXCL-8)
“Clean up on aisle 8”
Secreted by macrophages. Major chemotactic factor for neutrophils
IL-10
Secreted by Th2 cells. Modulates inflammatory response. Inhibits actions of activated T cells and Th1. Also secreted by regulatory T cells. TGF-beta has similar actions to IL-10, because it is involved in inhibiting inflammation
IL-12
Secreted by macrophages and B cells. Induces differentiation of T cells into Th1 cells. Activates NK cells.
TNF-alpha
Secreted by macrophages. Mediates septic shock. Activates endothelium. Causes leukocyte recruitment, vascular leak.
Neutrophil chemotactant agents
- IL-8
- Complement (C5a)
- Leukotriene B4
Interferon Gamma (IFN-gamma)
Secreted by Th1 cells. Activates macrophages and Th1 cells. Supresses Th2 cells. Has antiviral and antitumor properties
Interferon Alpha (IFN-alpha)
Secreted by virus-infected leukocytes. Produces ribonuclease that degrades viral mRNA inhibiting viral protein synthesis
Interferon Beta (IFN-beta)
Secreted by virus-infected fibroblasts. Produces ribonuclease that degrades viral mRNA inhibiting viral protein synthesis
Transforming growth Factor (TGF)
Secreted by T cells, B cells, and macrophages. Inhibits the growth and activities of T cells. Enhances collagen synthesis; dampens the immune response.
