Household Air Pollution Causes Dose-dependent Inflammation and Altered Phagocytosis in Human Macrophages

Background Three billion people are exposed to household air pollution from biomass fuel use. Exposure is associated with higher incidence of pneumonia, and possibly tuberculosis. Understanding mechanisms underlying these defects would improve preventive strategies. Methods We used human alveolar macrophages obtained from healthy Malawian adults exposed naturally to household air pollution, and compared with human monocyte-derived macrophages exposed in vitro to respirable-sized particulates. Cellular inflammatory response was assessed by: IL-6 and IL-8 production in response to particulate challenge; phagocytosis of fluorescent-labelled beads and intraphagosomal oxidative burst capacity; ingestion and killing of Streptococcus pneumoniae and Mycobacterium tuberculosis measured by microscopy and quantitative culture. Particulate ingestion was quantified by digital image analysis. Results We were able to reproduce the carbon loading of naturally exposed alveolar macrophages by in vitro exposure of monocyte derived macrophages. Fine carbon black induced IL-8 release from monocyte derived and alveolar macrophages (p