Effect of serial-day exposure to nitrogen dioxide on airway and blood leukocytes and lymphocyte subsets

Abstract

Nitrogen dioxide (NO2) is a free radical-producing oxidant gas. Inhalation of NO2 could cause airway inflammation, and decrease immune function. This experiment tested the hypothesis that exposure to NO2 would: 1) increase leukocytes in bronchoalveolar lavage (BAL); and 2) change the distribution of lymphocyte subsets and activation in BAL and peripheral blood (PB). Using a counter-balanced, repeated-measures design, 15 healthy volunteers were exposed to filtered air (FA) or 2.0 parts per million NO2 for 4 h x day(-1) (4 x 30 min of exercise), for three consecutive days. Bronchoscopy was performed 18 h following each exposure set, and PB was drawn pre-exposure and pre-bronchoscopy. Flow cytometry was used to enumerate lymphocyte subsets and activation makers in BAL and PB. In the bronchial fraction, there was an increase in the percentage of neutrophils following NO2 exposure compared to FA (median (interquartile range): 10.6 (4.8-17.2)% versus 5.3 (2.5-8.3)%; p=0.005). In the BAL, there was a decrease in the percentage of T-helper cells following NO2 exposure compared to FA (55.9 (40.8-62.7)% versus 61.6 (52.6-65.2)%; p=0.022). For PB, there were no between-condition differences in any leukocyte or lymphocyte subsets, or activation. In conclusion exposure to nitrogen dioxide results in bronchial inflammation and a minimal change in bronchoalveolar lavage T-helper cells, and no changes in peripheral blood cells.

Air pollution exposure affects circulating white blood cell counts in healthy subjects: the role of particle composition, oxidative potential and gaseous pollutants – the RAPTES project

“…For instance, Frampton et al (2002) reported a significant decrease in blood lymphocytes with short-term exposures to 0.6 and 1.5 ppm NO 2 in healthy subjects, whereas Rubinstein et al (1991) observed a nonsignificant increase in total WBC for 0.6 ppm NO 2 exposure using a similar study design. Repeated exposure to 2.0 ppm NO 2 did not induce cellular changes in blood (Solomon et al, 2000). NO 2 concentrations used in these studies were far above the levels measured in our study, yet we observed strong and consistent associations between NO 2 and the number of lymphocytes and eosinophils.…”

Chronic Exposure to Ambient Ozone and Lung Function in Young Adults

“…increases in inflammatory markers in respiratory tract lining fluid. [47][48][49] Thus, our data are best interpreted as an expression of the oxidant environments to which the subjects were exposed over their lifetimes, as well as to effects specific to the oxidant properties of O 3 itself. That our data do reflect, at least in part, some effects that are specific to O 3 relates also to the functional abnormalities observed.…”

Immunological biomarkers in salt miners exposed to salt dust, diesel exhaust and nitrogen oxides

“…The results of the challenge studies (exposure between 0.6-4 ppm NO 2 ) suggest inflammatory changes in bronchoalveolar lavage (BAL) and blood, but the (Blomberg et al 1997;Sandstro¨m et al 1992;Solomon et al 2000;Frampton et al 2002).…”