Cigarette Smoking in HIV Infection Induces a Suppressive Inflammatory Environment in the Lung

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Abstract
Lung lymphocyte numbers are frequently increased in human immunodeficiency virus (HIV)-infected individuals in the absence of lung infection, and may play a critical role in viral surveillance and protection against new infections. In this context, cigarette smoking by HIV-infected individuals has been associated with a relative increase in the peripheral blood CD4(+) T-lymphocyte count as compared with that of nonsmokers. Because lung defense is local, the aim of the present study was to determine whether cigarette smoking had a significant impact on local lung defenses in HIV-infected individuals. The numbers and subtypes of bronchoalveolar lymphocytes and the ability of lung lavage cells to produce proinflammatory cytokines were compared in 58 smokers and 34 nonsmokers. In contrast to a trend toward an increase in peripheral blood CD4(+) cell counts among nonsmokers, smokers had significant depressions in both the percentage and absolute numbers of CD4(+) and CD8(+) cells in their bronchoalveolar lavage fluid (BALF). A decrease in CD4(+)/CD8(+) cell ratios was also seen with smoking. In addition, production of both interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha) was suppressed with cigarette smoking. These observations show that cigarette smoking is associated with suppression in localized lung defenses, and suggest that smoking cessation may have a positive impact on lung defenses in HIV-infected smokers.