Interferons (IFNs) are a group of signaling proteins made and released by host cells in response to the presence of several pathogens, such as viruses, bacteria, parasites, and also tumor cells. In a typical scenario, a virus-infected cell will release interferons causing nearby cells to heighten their anti-viral defenses. IFNs belong to the large class of proteins known as cytokines, molecules used for communication between cells to trigger the protective defenses of the immune system that help eradicate pathogens. Interferons are named for their ability to "interfere" with viral replication by protecting cells from virus infections. IFNs also have various other functions: they activate immune cells, such as natural killer cells and macrophages; they increase host defenses by up-regulating antigen presentation by virtue of increasing the expression of major histocompatibility complex (MHC) antigens. Certain symptoms of infections, such as fever, muscle pain and "flu-like symptoms", are also caused by the production of IFNs and other cytokines. More than twenty distinct IFN genes and proteins have been identified in animals, including humans.
Transforming growth factor beta (TGF-β) is a multifunctional cytokine belonging to the transforming growth factor superfamily that includes four different isoforms (TGF-β 1 to 4, HGNC symbols TGFB1, TGFB2, TGFB3, TGFB4) and many other signaling proteins produced by all white blood cell lineages. Activated TGF-β complexes with other factors to form a serine/threonine kinase complex that binds to TGF-β receptors, which is composed of both type 1 and type 2 receptor subunits. After the binding of TGF-β, the type 2 receptor kinase phosphorylates and activates the type 1 receptor kinase that activates a signaling cascade. This leads to the activation of different downstream substrates and regulatory proteins, inducing transcription of different target genes that function in differentiation, chemotaxis, proliferation, and activation of many immune cells.
| Cytokine | Productive cell | Action |
| Interferonα | White blood cell | Antiviral action、MHC class I enhanced expression、NK-cell activation |
| Interferonγ | T-cell、NK-cell | Antiviral action、MHC class I enhanced expression、NK-cell activation |
| TGF-β1 | Chondrocyte、Macrophage、T-cell | Decrease in cell proliferation、Anti-inflammatory action (Th1-cell control/ macrophage control)、Extracellular matrix production、Iga production inducing |
| TGF-β2 | Chondrocyte、Macrophage、T-cell | Decrease in cell proliferation、Anti-inflammatory action (Th1-cell control/ macrophage control)、Extracellular matrix production、Iga production inducing |
| IL-1b | Monocyte、Macrophage、Dendritic cell | T-cell activation、Macrophage activation、IL-6production inducing、Endothelial cellE-selectin induced expression、Liver cell stimulation、Fever |
| IL-1ra | IL-1 antagonist | |
| IL-2 | T-cell activate | T-cell proliferation、B-cell proliferation/ differentiation、NK-cell proliferation/ differentiation |
| IL-4 | T-cell activate (Th2)、NKT-cell、Mast cell、Basocyte | B-cell activate/ proliferation、IgE/ IgG4 production inducing、Induced differentiation to Th2-cell、Inducing proliferation |
| IL-5 | Activate T-cell (Th2)、Mast cell | Acidocyte proliferation and differentiation、IgA production-inducing、CD5+B cell differentiation |
| IL-6 | T-cell activation、Macrophage、Endothelial cell | T-cell and B-cell proliferation and differentiation、Liver cell acute phase protein production-inducing、Blood stem cell cytodifferentiation/ inducing proliferation、Thrombocytosis |
| IL-7 | Bone marrow stroma cell、Thymus stroma cell、Lien activate T-cell (Th2) | Pre-B cell and pre-T cell inducing proliferation |
| IL-9 | T-cell activate (Th2) | Mast cell proliferation、T-cell proliferation |
| IL-10 | Tｈ2、Macrophage、Epstein-Barr virus | IL-1βIL-12 microphage production control、Costimulator suppressed expression、Th1-cell IFN-γ production control、Th2-cell differentiation-promoting |
| IL-12 | B-cell、Microphage、Dendritic cell | NK/ T-cell to IFN-γ production、NK-cell activation、Th1-cell inducement |
| IL-13 | T-cell activation | B-cell activation and proliferation、IgE production inducement、Microphage control |
| IL-15 | T-cell activation、NK-cell | IL-2 active、T/ B/ NK cells proliferation and differentiation |
| IL-17 | ||
| TNF-α | Microphage、Dendritic cell | Localized inflammation、Endothelial cell activation、Apoptosis induction、NF-κB activation、Fever、Blood clotting |
| G-CSF | Vascular endothelial cell、Microphage、Bone marrow stroma cell | Granulocyte proliferation and differentiation |
| GM-CSF | Bone marrow stroma cell、T-cell activation、Fibroblast、microphage | Marrow monocyte series proliferation and differentiation |
| Chemokine | Productive cell | active |
| IL-8 | Monocyte、microphage、Fibroblast、Vascular endothelial cell、Mast cell、Epidermal cell | |
| IP-10 | Monocyte、Fibroblast、Vascular endothelial cell | |
| MCP-1 | Monocyte、Fibroblast、Vascular endothelial cell | |
| MIP-1α | microphage、Monocyte、T-cell、B-cell、Heterophilic leucocyte、Mast cell | |
| MIP-1β | Monocyte、T-cell、B-cell、Heterophilic leucocyte | |
| RANTES | T-cell、Monocyte、microphage、Fibroblast、Vascular endothelial cell、Blood disc、Acidocyte、Respiratory epithelium | |
| eotaxin | Respiratory epithelium、Vascular endothelial cell、Fibroblast |
The regulatory T cells, formerly known as suppressor T cells, are a subpopulation of T cells that modulate the immune system, maintain tolerance to self-antigens, and prevent autoimmune disease. T-regs are immunosuppressive and generally suppress or downregulate induction and proliferation of effector T cells.