CD(11b) upregulation in nasal polymorphonuclear leukocytes as a potential marker of atmospheric pollutant exposure

Air pollutants are known to induce acute inflammatory responses in the respiratory tract of experimental animals and humans. This study was designed to explore whether young adults chronically exposed to a polluted urban atmosphere with ozone (O₃) as the major pollutant, have a significant nasal neutrophilic influx and if the expression of the β2 integrin CD(11b) in these cells could serve as an exposure biomarker. Polymorphonuclear leukocyte (PMN) nasal influx, nasal PMN-CD(11b) surface expression, rhinoscopic changes, and respiratory symptoms were evaluated in eighteen nonsmoker male volunteers, permanent residents in Southwest Metropolitan Mexico City (SWMMC). Twenty-one subjects living in Pacific and Gulf of Mexico ports served as controls. Nasal lavages (NALs) were done on the exposed subjects on five different summer days under variable atmospheric and meteorological conditions. In both control and exposed groups, nasal PMN values were similar on two of the three sampling dates, while in the third, samples were below control values. SWMMC residents were distinguished at all sampling dates by a significant upregulation of their NAL-PMN-CD(11b) expression compared to the control group (p < 0.001). Stimuli that increase the surface expression of CD(11b) on mature granulocytes have been characterized in bronchioalveolar lavages of subjects exposed to O₃ in experimental chambers. These include eicosanoids (i.e., leukotrienes, prostaglandins) as well as interleukins. Upregulation of CD(11b) in exposed populations would allow the airway neutrophils to be in close contact with endothelial and epithelial cells and initiate a cascade of events, such as oxidative-related damage and release of powerful proteolytic enzymes, eicosanoid and prostanoid products. The results of this study suggest an important CD(11b) upregulation in the neutrophils obtained from NALs of subjects chronically exposed for several hours a day to photochemical pollutants, while in the same group, the nasal PMN influx was not significant.