Changes in T-lymphocyte subpopulations and natural killer cells following exposure to ambient levels of nitrogen dioxide.

The effects of ambient levels of NO2 on murine splenic T-lymphocyte subpopulations and natural killer cells were investigated. AKR/cum and C57BL/6J mice were exposed, in inhalation chambers, to 0.25 ppm NO2 for 7 wk and 0.35 ppm NO2 for 12 wk, respectively. Monoclonal antibody technology was used in conjunction with fluorescence-activated cell sorter (FACS) analysis to detect quantitative changes in total T-lymphocytes (Thy-1.2-positive), mature T-lymphocytes (Lyt-1-positive), T-helper/inducer lymphocytes (L3T4-positive), T-cytotoxic/suppressor lymphocytes (Lyt-2-positive), and natural killer cells (asialo GM1-positive). Percentages of all T-lymphocyte subpopulations tested and natural killer cells were lower in spleens of mice exposed to NO2 compared to filtered-air controls. This is the first report providing evidence linking alterations in T-lymphocyte subpopulations and natural killer cells to NO2 exposure at ambient levels. Changes in T-lymphocyte subpopulations detected by FACS and correlated to impaired immune function may provide an extremely sensitive means of demonstrating NO2-induced changes in the immune system.