Figure 3 TNFα production by blood cells of COPD patients and control subjects. Heparinised whole blood was diluted 1:20 in RPMI 5% fetal calf serum and TNFα production was measured by a dynamic immunoassay during a 24 hour culture period. Cells were incubated 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 11 non‐smoking controls, 10 smoking controls, 9 steroid free COPD patients, and 8 steroid treated COPD patients.