You are here:
EVALUATION OF IMMUNOTOXICITY OF AN URBAN PROFILE OF NITROGEN DIOXIDE: ACUTE, SUBCHRONIC, AND CHRONIC STUDIES
Citation:
Selgrade, M., M. Daniels, AND E. Grose. EVALUATION OF IMMUNOTOXICITY OF AN URBAN PROFILE OF NITROGEN DIOXIDE: ACUTE, SUBCHRONIC, AND CHRONIC STUDIES. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-91/273 (NTIS PB92113356).
Description:
While a number of studies have demonstrated suppression of extra- pulmonary immune responses following exposure to NO2, an ubiquitous ambient and indoor air pollutant, most of these studies have utilized extremely high concentrations of NO2 relative to the environment. ur intent was to assess effects of NO2 on extra-pulmonary immune responses using an exposure regimen that was more relevant to environmental conditions. ats were exposed for 1, 3, 13, 52, or 78 wk to air or a pattern of NO2 designed to mimic episodic pollution in urban areas at concentrations 2-5 times those commonly seen in such areas. aily exposures consisted of 0.5 ppm for 16h, a 6 h exposure spike during which the concentration rose to 1.5 ppm, remained there for 2 h, and then returned to 0.5 ppm, and a 2 h down time. ats were exposed to this profile 5 days/wk; weekend exposures did not include the spike. lood was drawn and spleens were removed at the end of each exposure period. pleen cells were assessed for natural killer (NK) cell activity and responses to T-cell mitogens, phytohemagglutinin and concana-valin A, and the B-cell mitogen, Salmonella typhimurium glycoprotein. eripheral blood lymphocyte (PBL) responses to T-cell mitogens were also assesses. o changes as a result of NO2 exposure were observed in sections from spleen, femur (including marrow), thymus, and mandibular, peribronchial and mediastinal lymph nodes taken from similarly treated rats and examined histopathologically. here were no NO2-related changes in mitogen responses although significant suppression of these responses in both air and NO2 groups was noted in the spleen at 52 and 78 wk, and in PBL at 13, 52, and 78 wk, presumably as a result of aging. uppression of NK cell activity was noted after 3 wk of exposure but not after 1, 13, 52, or 78 wk of exposure. Age did not appear to affect NK cell activity. he transient suppression of NK cell activity may be important in light of reports of enhanced susceptibility of mice to challenge with syngenic tumor cells or murine cytomegalovirus. he data suggest that effects of NO2 on NK cell activity deserve further study.