Receptors for adhesion molecules are induced on monocytes exposed to PM10

Inhalation of urban particles (PM 10 ) has been linked to systemic effects such as alterations in the circulatory system. In previous studies, rats exposed to particles, presented monocytes adhering to the blood vessels distant from the lung (Nurkiewicz et al. Environ Health Perspect. 2006;114(3):412-419). The adhesion of monocytes to endothelial cells is mediated by adhesion molecules (i.e. selectins, ICAM-1, VCAM-1, PECAM-1) expressed in the endothelial cells and their receptors (i.e. PSGL-1, sLex, LFA-1, VLA-4 and aVb3), expressed in activated monocytes. In the present study we exposed in vitro human monocytes to PM 10 from Mexico City. The monocytes were exposed during 1, 2, 3, 18 and 24 h and the expression of PSGL-1, sLex, LFA-1, VLA-4 and aVb3 were measured by means of flow cytometry. The tested concentrations ranged from 0.001 μg/mL up to 30 μg/mL. At 3h, a significant increase (p < 0.05) of PSGL-1 and sLex expression was observed from 0.03 μg/mL (Fig 1). The concentrations of 0.001 to 0.01 μg/mL did not induce the expression of these molecules. After 18 h of exposure, the expression of LFA-1 and VLA-4 were induced at all concentrations from 0.03 μg/mL (p 10 to activate human monocytes. Thus, low concentrations of PM 10 inducing the expression of these molecules may be linked to systemic effects induced by inhaled particles.