IL17A and Arthritis: In addition, the arthritis in the anti-IFN-γ group was associated with significantly elevated IFN-γ, IL-4, and IL-17 levels in the joints, whereas the arthritis in the anti-IFN-γ + anti-IL-4 group was associated with significant increase in IFN-γ and IL-4 and a modest increase in IL-17 responses (Figure 3c).