Macrophages in respiratory system

Macrophages are the key player of the immune system and locate all over the body to ensure a healthy life. The lung is a vital organ of our body that exchanges oxygen and carbon dioxide to and from the body. However, it always contacts the external environment and is infected with external biotic and abiotic contaminants. Asthma, lung cancer, pulmonary fibrosis, pneumonia, tuberculosis, etc., are the most common respiratory illnesses. Alveolar macrophages and interstitial macrophages are the common types of macrophages expressed in the lung to protect the lung. They originate from the precursor cells in hemopoietic organs and enter the respiratory tract via lymph and blood. Macrophages are present in almost all the tissue in the body and start a defensive mechanism in the damaged tissues by phagocytosis, release proinflammatory and toxic contents into the environment. They can activate acquired and innate immunity in the presence of any microorganism or other harmful substances. Macrophages can protect from different kinds of bacteria, viruses, fungi, inhaled particulate matter, and ambient chemicals. Though macrophages can be disabled in some disease conditions and drugs, the protective mechanism of macrophages in the respiratory system cannot be denied.