Inclusion Criteria:  Patients with ILD (hypersensitivity pneumonitis) with age between18 and 65 years old. Symptoms including dry cough and shortness of breath. Significant decrease in pulmonary function (desaturation by 4% after 6-minute walk distance), where the patients were no more controlled on their prednisolone maintenance therapy (up to 10 mg/day). Chest CT showing ground glass opacity and band of shadow.  Exclusion Criteria:  Patients with any other organ affliction (heart failure (ejection fraction 40-50%), renal failure (decrease in glomerular filtration rate > 75%), or liver cirrhosis (transient elastography liver stiffness measurements 12.5-75.5 kPa)). Active infection. Patients on other immunosuppressive medications (e.g., cyclophosphamide) and anti-fibrotic (e.g., interferon, pirfenidone, endothelin-1 antagonist and tumor necrosis factor α modulator). History of pulmonary embolism (corticosteroids' use increase the risk of recurrence of pulmonary embolism). Pregnancy.