MPO and interstitial lung disease: NE (P = 0.226) and MPO (P = 0.067) did not differ significantly between patients in the RP-ILD and non-RP-ILD groups; however, IL-6 (P = 0.0002) level was significantly lower in patients in the RP-ILD group (see Figures 2(a), 2(c), and 2(d)).