Important Cytokines

IL-1

• secreted by macrophages

• causes fever, acute inflammation

• activates endothelium to express adhesion molecules

• induces chemokine secretion to recruit WBCs

IL-6

• secreted by macrophages

• Causes fever

• stimulates production of acute-phase proteins (ex: CRP)

TNF-alpha

• Secreted by macrophages

• activates endothelium

• Causes WBC recruitment, vascular leak (into tissues)

• Causes cachexia in malignancy

IL-8

• Secreted by macrophages

• Chemotaxis of neutrophils

IL-12

• secreted by macrophages

• Induces differentiation of T cells → Th1 cells

• Activates NK cells

IL-2

• Secreted by T-cells

• Stimulates growth of helper, cytotoxic, regulatory T-cells and NK cells

IL-3

• Secreted by T-cells

• Supports growth and differentiation of bone marrow stem cells; functions like GM-CSF

IFN-gamma

• secreted by Th1 cells and NK cells in response to antigen or IL-12 from macrophages

• Stimulates macrophages to kill phagocytosed pathogens

• Inhibits differentiation of CD4+ cells into Th2 cells

• Induces IgG isotype switching in B-cells

• Increases MHC expression and antigen presentation by all cells

IL-4

• Secreted by Th2 cells

• Induces T cells → Th2 cells

• Promotes growth of B-cells

• Class switching to IgE and IgG

IL-5

• Secreted by Th2 cells

• Promotes growth and differentiation of B-cells

• Enhances class-switching to IgA

• Stimulates growth and differentiation of eosinophils

IL-10

• secreted by Th2 cells and Treg

• atTENuates inflammatory response

• decreases expression of MHC Class II and Th1 cytokines

• Inhibits macrophages and dendritic cells

IL-13

• Secreted by Th2 cells

• Promotes IgE production by B-cells

• Alternative macrophage activation