INTEGRIN UP-REGULATION ON SPUTUM NEUTROPHILS IN SMOKERS WITH CHRONIC AIRWAY-OBSTRUCTION

To determine the relationship between the expression of leukocyte-spec ific integrins in the airways and the airway obstruction in smokers, w e analyzed hypertonic saline-induced sputum in 33 male subjects, age 6 4.7 +/- 0.5 yr (mean +/- SEM), with a smoking history of 12 to 94 pack -years, at the end of a 15-yr follow-up study. Average FEV(1)/VC ratio was 69 +/- 1% at the beginning of the study and 66 +/- 2% at the end of the follow-up period, and annual decline of FEV(1) was 20 +/- 3 ml/ yr. Fourteen individuals exhibited airway obstruction as assessed by a FEV(1)/VC ratio lower than 63.3%. Differential leukocyte count was pe rformed on cytospin preparations and the expression of integrin alpha (CD11a, CD11b, CD11c) and beta (CD18) chains was assessed on granulocy tes and mononuclear cells by immunocytology. The numbers of neutrophil s expressing CD11b and CD18, but not CD11c or CD11a, were increased in the subjects with airway obstruction compared with those without airw ay obstruction. CD11b- and CD18-positive neutrophils were negatively c orrelated with FEV(1)/VC ratio (p < 0.01). No significant correlations were found between CD11a-, CD11b-, CD11c-, CD18-positive mononuclear cells and lung function measurements. In conclusion, our results sugge st that leukocyte-specific integrin CD11b/CD18 expressed on sputum pol ymorphonuclear leukocytes represents a marker for the smokers who deve lop chronic airway obstruction.