Progress in Research on T Helper 17 Cells and Onset of Relevant Diseases

T helper 17(Th17) cells are a newly identified subset of T helper cells that play important roles in host defense against microorganism.Th17 cells are also involved in the pathogenesis of various autoimmune diseases such as allergy,diabetes,rheumatoid arthritis and so on.Th17 cells are a unique helper T-cell subset different from Th1 and Th2 cells,which secret several cytokines including IL-17A,IL-17F,IL-21,and IL-22.This review provides a summary of the primary biological functions of Th17 cells as well as their correlations to infectious and autoimmune diseases.