Responses of alveolar macrophages to post-Gulf-war airborne Dust from Kuwait

The Kuwait oil fires of 1991 resulting from the Iraqi invasion created an unprecedented environmental pollution to which the population was exposed for a prolonged period. The impact of such pollution on human health, especially the respiratory system, needs to be adequately assessed, given the well known relationship between air pollution and respiratory diseases. Alveolar macrophages (AM) are the main resident cells in the bronchial lumen and are known to perform microbicidal and tumoricidal roles by releasing oxygen radicals and cytokines. The effects of the extracts and particles of the post oil fire airborne dust collected from air conditioner filters in the Ahmadi area of Kuwait in 1991-1995 on the in vitro spontaneous and PMA-stimulated generation of superoxide ions (O-2) from guinea pig AM and lipopolysaccharide (LPS)-stimulated tumor necrosis factor (TNF alpha) release from mouse AM were studied. Treatment of adherent AM with aqueous extract of the 1991 dust (0.6-10 mg/mL) resulted in a dose-dependent inhibition of basal, as well as PMA-induced O-2 release. At lower concentrations, slight increases were seen. Fifty percent inhibition of O; release was achieved by extracts of 1-2.4 mg/mL of the dust and at 10 mg/mL the maximal inhibition was 79-88%. At the same concentration range, the extract also inhibited the LPS-stimulated release of TNF alpha from mouse AM. These effects were more pronounced in the 1991 dust samples than in the 1992 and 1995 samples. No such effect was seen with the extract of silica (SiO2) used as particulate control. All washed dust or SiO2 particulates directly induced the release of both O-2 and TNF alpha from these cells. These results show that the post-oil fire airborne dust of Kuwait contained soluble pollutants that were capable of inhibiting the host defensive functions of the: AM and this may have possibly resulted in an increased susceptibility to respiratory infections and neoplasms among the exposed population. (C) 1998 Elsevier Science Ltd.