The relationship between immune defense mechanisms and
environmental pollutants has been a focus of intensive research during the last decade. In animal experiments,
diesel exhaust particles (
DEP) have been shown to exert adjuvant effects on the
IgE response against aeroantigens and to compromise broncho-pulmonary immune defense. Important target cells are monocytes/alveolar macrophages which display the important functions of phagocytosis, antigenpresentation and modulation of inflammatory processes. To further evaluate the influence of
DEP upon these cells, we investigated whether exposure to suspended
DEP would change the phagocytic capacity and the
tumor necrosis factor alpha (TNF-α) release of human peripheral monocytes/alveolar macrophages. Our results demonstrated a dose-dependent reduction of phagocytosis (p < 0.001) and an additional increase of an ongoing TNF-α response (p < 0.005). These findings may help to link exposure to
environmental pollutants to such
biologic effects as increased susceptibility to broncho-
pulmonary disease or facilitated sensitization against aeroallergens.