Method: The CD45+, CD34+, CD11b+ cells from 4 patients were isolated by cell sorting, and stained for Procollagen. 30 patients (10 of each RA, fibrotic ILDs: IPF or non-specific interstitial pneumonitis (NSIP), severe asthma) and 10 HC were included. Current medication, disease activity, lung function and radiographic data were collected. In 100 µL of lysed blood cells were enumerated by flowcytometry. Further, PBMC were isolated and cultured for 5 days. Coverslips from two wells were stained and mature fibrocytes counted and reported as fibrocytes per 106 PBMC originally added to the well.