Cytokine Families and Functions in Immune Response

What do Th1 cytokines generally do?

Promote cell-mediated immunity against intracellular pathogens; activate macrophages and CD8 T cells; pro-inflammatory

What do Th2 cytokines generally do?

Promote humoral immunity and responses against parasites; activate B cells, eosinophils, and IgE production

What do Th17 cytokines generally do?

Promote inflammation and recruit neutrophils to fight extracellular bacteria and fungi

What do Treg cytokines generally do?

Suppress immune responses, promote tolerance, and reduce inflammation

What do chemokines generally do?

Direct movement (chemotaxis) of immune cells to sites of infection

What do inflammatory cytokines generally do?

Amplify inflammation by activating leukocytes and endothelium

IL-2 - source and function

Made by Th1 cells; stimulates T cell proliferation and enhances NK/CTL activity

IFN-γ - source and function

Made by Th1, NK, CTLs; activates macrophages, increases MHC I/II expression, pro-inflammatory

IL-12 - source and function

Made by APCs; drives Th0 → Th1 differentiation and increases IFN-γ production

Are Th1 cytokines pro- or anti-inflammatory?

Pro-inflammatory

IL-4 - source and function

Made by Th2 and mast cells; induces Th2 differentiation and IgE class switching

IL-5 - source and function

Made by Th2 and mast cells; activates eosinophils

IL-6 - source and function

Made by many cells; promotes B cell development, can be pro- or anti-inflammatory

IL-10 - source and function

Made by Th2, Treg, macrophages; anti-inflammatory, inhibits Th1 responses

What pathogens do Th2 cytokines target?

Parasites (helminths)

IL-17 - source and function

Made by Th17 cells; recruits neutrophils and drives inflammation

What pathogens do Th17 cytokines target?

Extracellular bacteria and fungi

Are Th17 cytokines pro- or anti-inflammatory?

Strongly pro-inflammatory

TGF-β - source and function

Made by Treg and other cells; anti-inflammatory, promotes IgA class switching and immune tolerance

IL-10 - role in Treg function

Suppresses inflammatory cytokines and immune responses

Are Treg cytokines pro- or anti-inflammatory?

Anti-inflammatory

IL-1 - source and function

Made by APCs; increases vascular permeability, activates leukocytes

TNF-α - source and function

Made by many cells (esp. macrophages); major inflammatory cytokine, causes acute phase response and septic shock

IL-6 - role in inflammation

Stimulates acute phase response in liver; pleiotropic

What is a key feature of inflammatory cytokines?

Increase adhesion molecules and recruit immune cells

IL-8 (CXCL8) - function

Chemoattractant for neutrophils

What determines which cells chemokines recruit?

The chemokine receptor expressed on the target cell

Are chemokines pro- or anti-inflammatory?

Generally pro-inflammatory (recruit immune cells)

IFN-α and IFN-β - function

Antiviral; inhibit viral replication and increase MHC I expression

IFN-γ - role difference

More inflammatory; activates macrophages and promotes Th1 responses

What do CSFs (e.g., G-CSF, GM-CSF) do?

Stimulate production and function of myeloid cells (neutrophils, macrophages)

Are CSFs inflammatory?

Generally pro-inflammatory/supportive

Which cytokine can belong to multiple families?

IL-10 (Th2 and Treg), IL-6 (Th2 and inflammatory), IFN-γ (Th1 and inflammatory)

What is pleiotropy in cytokines?

One cytokine having different effects on different cells

What is redundancy in cytokines?

Multiple cytokines having the same effect

Which cytokine induces IgA class switching?

TGF-β