IL17A and rheumatoid arthritis: The discovery of Th17 cells (100, 101) and the delineation of the IL-17 family members (104) as well as the shift from Th17 cells to Th1 cells (i.e., “non-classic Th1 cells”) being more pathogenic than Th17 cells per se shed new light on the contribution of inflammatory Th subsets to the initiation of RA (Figure 2) (105–108).