Figure 1 TNFα production by sputum cells of COPD patients and control subjects. TNFα production by sputum cells (20 000 cells/well) was measured by a dynamic immunoassay during a 24 hour culture period. Cells were incubated in RPMI 5% fetal calf serum without LPS (blank) or with LPS 1 ng/ml or 10 ng/ml. Data are presented as median with interquartile range (box) and range (whiskers) for 10 non‐smoking controls, 10 smoking controls, 9 steroid free COPD patients, and 8 steroid treated COPD patients. The p values indicate differences compared with spontaneous TNFα production by sputum cells from non‐smoking controls.