Reasons for rarity of Th17 cells in inflammatory sites of human disorders

A second reason for the rarity of human Th17 cells in the inflammatory sites is their rapid shifting into the Th1 phenotype, which is mainly related to the activity of IL-12 and TNF-α. We have named these Th17-derived Th1 cells as non-classic because they differ from classic Th1 cells for the expression of molecules specific for Th17 cells, such as RORC, CD161, CCR6, IL4I1, and IL-17 receptor E. This distinction may be important for defining the respective pathogenic role of Th17, non-classic Th1 and classic Th1 cells in many human inflammatory disorders.