Immune biomarkers in relation to exposure to particulate matter: A cross-sectional survey in 17 cities of central Europe

Human population data on air pollution and its effects on the immune system are scarce. A survey was conducted within the framework of the Central Eur opean Study of air Quality and Respiratory Health (CESAR) to measure a pane l of immune biomarkers in children of Bulgaria, Czech Republic, Hungary, Po land, Romania, and Slovakia. Seventeen cities were chosen to represent a wi de range of exposure to outdoor air pollution, in each, ambient particulate matter of less than 10 mum diameter and less than 2.5 mum diameter (PM10 a nd PM2.5) were measured with a Harvard impactor. Blood was collected from 3 66 school children aged 9 to 11 yr between 11 April and 10 May 1996. The pe rcentage of B, total T, CD4+, CD8+, and natural killer (NK) lymphocytes was determined by flow cytometry (Becton Dickinson); total immunoglobulins of class G, M, A and E (IgC, IgM, IgA, and IgE) were measured in serum using n ephelometry (Behring). Associations between PM and each log-transformed bio marker concentration were studied by linear regression, in a two-stage mode l. The yearly average concentrations varied from 41 to 96 mug/m(3) for PM10 across the 17 study areas, from 29 to 67 mug/m(3) for PM2.5, and from 12 t o 38 mug/m(3) for PM10-2.5 (coarse). Number of B, CD4+, CD8+, and NK lympho cytes increased with increasing concentration of PM, having adjusted for ag e, gender, parental smoking, laboratory of analysis, and recent respiratory illness. Differences in lymphocyte number were larger and statistically si gnificant for exposure to PM2.5. Similar results were found when we examine d the association between PM and lymphocyte number separately for each labo ratory. Total IgG was increased with increasing concentration of PM, signif icantly in the case of PM2.5. When we repeated the analyses with two other statistical approaches the results did not differ from those reported here. The effect of coarse PM on lymphocyte numbers appears small in comparison to PM2.5. One possible interpretation of our findings is that long-term exp osure to airborne particulates leads to inflammation of the airways and act ivation of the cellular and humoral immune system.