Abstract
Habitual marijuana smoking may cause a number of potentially harmful effects on the lung, including the following: (1) acute and chronic bronchitis; (2) extensive histopathologic alterations in the cells lining the bronchial passages that could impair mucociliary clearance or predispose to malignancy; (3) increased accumulation of inflammatory cells (alveolar macrophages) in the lung; and (4) impairment in the function of these important immune-effector cells, including their ability to kill microorganisms and to produce protective pro-inflammatory cytokines. The major potential pulmonary consequences of habitual marijuana use are pulmonary infection and respiratory cancer. Infectious complications could be due to smoking-related damage to the muco-ciliary clearance mechanism, marijuana-related impairment in the antimicrobial function of alveolar macrophages and/or fungal or bacterial contamination of marijuana. Patients with pre-existing immune deficits due to AIDS could be particularly susceptible to pulmonary infectious complications of marijuana use.