Because lung tissues from IPF patients have been reported to express up-regulated alarmins (thymic stromal lymphopoietin and IL-33) and down-regulated GRα and HDAC2 compared to those from patients with COP and sarcoidosis (8, 18, 19), we hypothesized that increased levels of another alarmin, IL-17, may also contribute to corticosteroid insensitivity in IPF. The gene discussed is IL17A; the disease is cryptogenic organizing pneumonia.