Pulmonary mast cells are mainly distributed in the surrounding of pulmonary vessels, bronchi, and mucosa. When pathogens invade, they are directly phagocyted by mast cells through endocytosis. In addition, pulmonary mast cells participate in the antigen presentation of pathogens, and then mediate cellular and humoral immunity. In conclusion, mast cells play an important role in protecting lung from pathogen infection.