RNase protection assay of mRNA expression by AM and HBEC. Representative autoradiographs of RNase protection assays (RPAs) showing mediator expression by AM/HBEC co-cultures, AM mono-cultures and HBEC mono-cultures after 2 and 24 h incubation in medium alone (control) or a 100 μg/ml of PM10 suspension (PM10). After 24 h exposure AM showed increased expression of LIF and ICAM-1 mRNA. Expression of GM-CSF, LIF and ICAM-1 mRNA by HBEC was increased by 24 h PM10 stimulation compared to their respective controls. MIP-1β, GM-CSF, M-CSF, MCP-1, IL-6, LIF and ICAM-1 mRNA expression by AM/HBEC co-cultures was increased 2 and/or 24 h after incubation with PM10 compared to control. L32 and GAPDH were used as controls for lane loading.