Figure 2.

Main activities attributed to Th17 cells. IL-17 producing CD4⁺ T helper (Th17) cells produce several cytokines, the most important being IL-17 or IL-17A, which activated multiple cell types to produce proinflammatory cytokines, chemokines, nitric oxide synthase (NOS)-2, metallo-proteinases (matrix metalloproteinase [MMP]3) and colony-stimulating factor. This results in granulocyte recruitment, which plays an important role in protection against extracellular bacteria but also in macrophage recruitment and establishment of chronic inflammation. CCL, CC chemokine ligand; CXCL, CXC chemokine ligand; G-CSF, granulocyte colony-stimulating factor; GM-CSF, granulocyte/macrophage colony-stimulating factor; Th, T helper; TNF, tumour necrosis factor.