IL17A and arthritic joint disease: Interestingly, the balance of serum IL-17A/IFNγ showed a trend to be increased (P = 0.09) at D44 if P. gingivalis oral infection was present in mice developing arthritis in the CFA/CII group compared with CFA/CII alone, and a nonsignificant trend in IL-17F/IFNγ ratios (Figure 4B).