Interleukin ‐17 family cytokines in protective immunity against infections: role of hematopoietic cell‐derived and non‐hematopoietic cell‐derived interleukin‐17s

ABSTRACT Interleukin (IL)‐17 family cytokines consisting of six members participate in immune response in infections, autoimmune diseases and inflammatory diseases. The prototype cytokine of the family, IL‐17A, was originally identified from CD4+ T cells which are now termed Th17. Later IL‐17A‐producing cells are expanded to various hematopoietic cells including CD8+ T cells (Tc17), invariant NKT cells, γ δ T cells, non‐T non‐B lymphocytes termed type 3 innate lymphoid cells (ILC3), and neutrophils. Some members of the IL‐17 family cytokines other than IL‐17A were also expressed by CD4+ T cells: IL‐17E by Th2 cells, and IL‐17F by Th17 cells. IL‐17A and IL‐17F induce expression of pro‐inflammatory cytokines to induce inflammation and anti‐microbial peptides to kill pathogens, while IL‐17E induce allergic inflammation. However, function of other IL‐17 family cytokines had been unclear. Recent reports demonstrated that IL‐17B and IL‐17C are expressed by epithelial cells rather than hematopoietic cells. Interestingly, expression of IL‐17E and IL‐17F by epithelial cells have also been reported, and the epithelial cell‐derived IL‐17 family cytokines showed important role in immune response to infections at epithelial sites. In this review, we summarize current information on hematopoietic cell‐derived IL‐17A and non‐hematopoietic cell‐derived IL‐17B, IL‐17C, IL‐17D, IL‐17E and IL‐17F in infections, and propose function...
Source: Microbiology and Immunology - Category: Microbiology Authors: Tags: Review Source Type: research