Cytokines

TNF : Major sources

Macrophages, T cells

TNF : Core action

Activates endothelium, increases vascular permeability, recruits leukocytes, and promotes fever

TNF : Significance

Excess systemic TNF can contribute to septic shock

IL-1 : Major sources

Macrophages, DCs, tissue cells

IL-1 : Core actions

Promotes endothelial activation, leukocyte recruitment, and fever

IL-1 : Significance

Signals infection or tissue injury

IL-6 : Major sources

Macrophages, endothelial cells, fibroblasts

IL-6 : Core actions

Drives fever and hepatic acute-phase proteins such as CRP

IL-6 : Significance

Connects local inflammation to systemic responses

IL-8 (CXCL8) : Major sources

Macrophages, epithelial cells, and endothelial cells

IL-8 : Core actions

Chemokine that forms a gradient and recruits/activates neutrophils during acute bacterial or fungal infection

IL-17 : Major sources

Th17 cells, innate lymphocytes

IL-17 : Core actions

Stimulates tissue cells to recruit neutrophils and produce antimicrobial signals

IL-17 : Significance

Protects barriers from extracellular bacteria and fungi

IL-10 : Major sources

Treg cells, macrophages, DCs

IL-10: Core actions

Suppresses inflammatory cytokines and APC activation

IL-10 : Significance

Limits tissue damage and promotes resolutions

TGF-β : Major sources

Treg cells, immune and tissue cells

TGF-β : Core actions

Limits immune activation, supports Treg development, IgA switching, repair, and matrix production

TGF-β : Significance

Persistent activity may promote fibrosis

Interferons : Major sources

Type I: infected cells/DCs

Type II: NK and T cells

Interferons : Core actions and significance

IFN-α/β induce antiviral defenses and increase MHC I

IFN-γ activates macrophages and strengthens cell-mediated immunity

IL-4 : Major sources

Th2 cells, mast cells

IL-4 : Core actions

Directs Type 2 immunity, Th2 development, IgE class switching, and alternative macrophage activation

IL-4 : Significance

Important in parasite responses and allergy

IL-2 : Major sources

Activated T cells

IL-2 : Core actions and significance

Promotes survival and clonal expansion of activated T cells and supports regulatory T-cell maintenance

G-CSF : Major sources

Macrophages, endothelial and stromal cells

G-CSF : Core actions

Stimulates neutrophil precursor survival, differentiation, and release

G-CSF : Significance

Therapeutically used to increase neutrophil counts

GM-CSF : Major sources

T cells, macrophages, endothelial and stromal cells

GM-CSF: Core actions and significance

Supports broader myeloid development and activation including granulocytes, monocytes/macrophages, and some dendritic cells