Although the mechanisms responsible for lung damage and respiratory function deterioration for each type of alveolitis are not entirely known, with the opportunity to study the cells present in the lower respiratory tract, their functions and the mediators released in different conditions, we will be able to better understand the link between the inflammatory process, the acute tissue damage, the progression of the disease and the pulmonary scarring. This knowledge will be helpful in a better management of patients with interstitial lung diseases modulated by immunologic mechanisms.