Leucocyte migration in the presence and absence of a soluble lung homogenate has been studied in a group of asymptomatic cigarette smokers. Results were expressed as migration indices. Controls consisted of age-matched subjects who had never smoked and had no past history of any pulmonary disease. The migration indices, the number of pack-years* smoked and the results of pulmonary function studies were tested for correlation.
The mean leucocyte migration index of the test group of sixteen smokers was significantly less than was that of the control group (P < 0·001). Inhibition of leucocyte migration in the presence of the lung homogenate was not observed in any of the control subjects. Six of the sixteen asymptomatic cigarette smokers, however, were identified by inhibition of leucocyte migration in the presence of the lung homogenate. The number of pack-years which had been smoked did not correlate with the migration indices (r=−0·06); however, inhibition of leucocyte migration was not observed in subjects who had smoked less than 6 pack-years.