12 Aug 09
Immunologic aspects of chronic obstructive pulmonary disease
By M Cosio, M Saetta and A Agusti
Chronic obstructive pulmonary disease (COPD) is a major cause of illness and death throughout the world. It affects about 10% of the general population, but its prevalence among heavy smokers can reach 50%. COPD is the fourth leading cause of death in most industrialized countries, and it is projected to be the third leading cause of death worldwide by 2020. Tobacco smoking is the primary risk factor for the development of COPD, but other factors, such as burning biomass fuels for cooking and heating, are important causes of COPD in many developing countries.
A principal feature of COPD is a limitation of airflow that is not fully reversible and is associated with an abnormal inflammatory response in the small airways and alveoli. The principal abnormalities in small airways are the presence of an inflammatory cellular infiltrate and a remodeling that thickens the airway wall, thereby reducing the airway diameter and increasing resistance to flow. Additional features are prominent inflammatory infiltrates in the alveolar walls, destruction of alveoli, and enlargement of air spaces. These anatomical hallmarks of emphysema reduce the elastic pressure that generates expiratory flow. Chronic bronchitis, a condition that according to some authors has little to do with the development of airflow obstruction, develops in approximately 50% of smokers.