CCL18 and idiopathic pulmonary fibrosis: Analysis of the derivation cohort showed that serum CCL18 levels were significantly higher in the IPF patients (645 ng/mL [IQR 393 – 847]) compared with the healthy controls (185 ng/mL [IQR 123-272]), p < 0.0001, as shown in Figure 2A. The serum CCL18 levels (median 642 ng/mL [IQR 429-943] in eight patients who received low dose corticosteroids were not significantly different from those of the IPF patients who did not receive immunosuppressive therapy (median 652 ng/mL; IQR 400-856; p = 0.880) at the time of sampling.