You are here:
AMBIENT PARTICULATE MATTER DECREASED IN HUMAN ALVEOLAR MACHROPHAGE CYTOKINE RELEASE
Citation:
SAWYER, K. AND M. C. MADDEN. AMBIENT PARTICULATE MATTER DECREASED IN HUMAN ALVEOLAR MACHROPHAGE CYTOKINE RELEASE. Presented at 2nd International Conference on Environmental Science and Technology, Houston, TX, August 19 - 22, 2006.
Description:
Human exposure to ambient airborne particulate matter (PM) is associated with cardiopulmonary mortality and morbidity, including increased hospitalizations for lung infection. Normal lung immune responses to bacterial infection include alveolar macrophage cytokine production and release, among other processes. Our previous research demonstrates that diesel exhaust particulate matter (DEP) suppresses AM response and release of cytokines to lipopolysaccharide (LPS), a gram-negative bacterial product. To examine whether ambient airborne PM induces similar effects, we exposed human AM in vitro to non-cytotoxic doses of fine (<2.5 ¿m) and coarse (2.5-10 ¿m) fall (November 2001) and summer (June 2002) concentrated ambient Chapel Hill particles, and Standard Reference Material (SRM) 1649 Urban Dust particles (UD). We also exposed AM to three control particles: carbon black, volcanic ash, and SRM 2975 (forklift DEP). (SRMs were obtained from the National Institute of Standards, Gaithersburg, MD). After a 24-hour exposure to PM, AM were stimulated with LPS and incubated for a second 24-hour period. Intra- and extracellular interleukin 8 (IL-8) and tumor necrosis factor alpha (TNF-¿) concentrations were measured at 6 and 24 hours post LPS stimulation. November 2001 and June 2002 Chapel Hill course and fine PM similarly suppress IL-8 and TNF-¿ release at 24-hrs post LPS stimulation relative to control AM cultures (LPS stimulation, but no particle exposure). The cytokine suppression ranged between 30% and 85% for low (25¿g/mL) and high (100¿g/mL) PM doses, respectively. Coarse PM appeared to have a greater inhibitory effect on extracellular cytokine concentrations than fine PM. UD particles also suppressed IL-8 release (72% decrease) at 24-hrs post LPS stimulation. The decreased extracellular cytokine concentrations in most PM treatments were due in part to increased intracellular cytokine retention. Inclusion of additional particle collection months will enable us to better examine seasonal influences on PM-induced cytokine suppression. AM cytokine inhibition may be an important step between PM exposure and the development of adverse respiratory health effects. (Supported by NHEERL-DESE Cooperative Training in Environmental Sciences Research, EPA CT826513. This abstract may not represent official EPA policy.)