Solomon JJ, Matson S, Kelmenson LB, et al. - Given that idiopathic pulmonary fibrosis (IPF) shares genetic, histopathologic, and radiographic characteristics with the fibrosing interstitial lung disease noted in rheumatoid arthritis (RA), so, researchers determined RA-associated autoantibodies in IPF. This analysis was performed with IPF patients from two separate cohorts at National Jewish Health and Brigham Women’s Hospital (n = 181), general population control individuals (n = 160), and controls having disease (n = 86 [40 with RA-usual interstitial pneumonia and 46 with hypersensitivity pneumonitis]). The probability of being IgA-ACPA (antibodies to citrullinated protein antigens)-positive vs IgG-ACPA-positive was more in IPF patients, whereas, a greater likelihood of being IgG-ACPA-positive than IgA-ACPA-positive was noted in RA patients. Overall, IPF patients had elevated IgA-ACPA, and there was a correlation of IgA-ACPA with lymphoid aggregates in the lung; these findings support the notion that there may be a role of IgA-ACPA in lung disease pathogenesis in a subset of people with IPF.