In vivo assessment of lung inflammatory cell activity in patients with COPD and asthma

The involvement of inflammatory cells in the pathogenesis of chronic obstructive pulmonary disease (COPD) and asthma is well established. This study aimed to quantify differences in inflammatory cell function in situ in these patients as compared to normal subjects. Positron emission tomography was used to assess neutrophil activity (18F-fluorodeoxyglucose (18FDG)) and macrophage accumulation (11C-PK11195) in six patients with COPD, six chronic asthmatics and five age-matched normal control subjects. 18FDG uptake was greater in COPD than in normal subjects, with no increase in asthmatics. The mean slope of 18FDG uptake, corrected for volume of distribution, was 4.0 min(-1) in COPD patients compared with 1.5 min(-1) in control subjects and 1.7 min(-1) in asthmatics. Mean 11C-PK11195 uptake (plateau tissue:plasma) was higher in four of six COPD patients (10.8) and three of five asthmatics (11.8) than the maximum value in control subjects (6.2). From this preliminary study the authors conclude that positron emission tomography may be useful to assess polymorphonuclear neutrophil and macrophage activity in vivo in chronic obstructive pulmonary disease and asthma, and may reveal differences in cell behaviour between the study groups. In addition, positron emission tomography may provide indices of disease activity for future therapeutic studies.