ABSTRACT
Clinical evidence exists demonstrating changes in platelet behavior and function in inflammatory diseases and infections of the respiratory tract, in particular in asthma, rhinitis, acute lung injury arising from Adult Respiratory Distress Syndrome (ARDS), COVID-19 and chronic obstructive pulmonary disease (COPD). Despite being anucleate, platelets participate in the pathogenesis of these disorders in a manner distinct from their effects in thrombosis and hemostasis. These include the expression of adhesion molecules, the release of proinflammatory mediators, tissue-degrading enzymes, cationic proteins, and the ability to undergo chemotaxis. Platelets can themselves be activated by mediators released by other inflammatory cells. There is now substantial experimental evidence that supports a role for platelets in the development of immunity, leukocyte recruitment to inflamed tissue, airways hyperresponsiveness, lung remodeling and repair, and pulmonary hypertension.