Effects of cigarette smoke on the lung and systemic immunity.

The influence of tobacco smoke on human health is still an important problem worldwide. Complex inflammatory processes and changes in the immune system are crucial in the pathogenesis of smoking related disorders like chronic obstructive lung disease (COPD), lung cancer, atherosclerosis. The objective of this review is to present the alterations in the immune system in smokers. The main affected system by cigarette smoke (CS) is the respiratory tract. In bronchial epithelium metaplastic and dysplastic changes are accompanied by elevated expression of adhesion molecules and secretion of many cytokines capable of stimulation immune cells influx. In the population of pulmonary macrophages an elevated proportion of cells, changes in expression surface markers with impaired phagocytic and antigen presenting function are observed. Chronic exposure to CS causes increased production of metalloproteinases (MMP) by macrophages and proteolitic enzymes by neutrophils. These enzymes cause destruction of alveolar wall. Increased apoptosis of lung tissue results in augmentation of foreign material which may play a role of autoantigen and which is a target for cytotoxic/suppressor cells. The role of regulatory T (Treg) cells in this process is recently postulated. Smoking cessation is the most effective method of prophylaxis and treatment of diseases related to tobacco smoking. However many immunological changes in smokers are not completely reversible after quitting smoking.