CD11B AND L-SELECTIN EXPRESSION ON EOSINOPHILS AND NEUTROPHILS IN BLOOD AND INDUCED SPUTUM OF PATIENTS WITH ASTHMA COMPARED WITH NORMAL SUBJECTS

Background Patients with asthma show altered surface expression of the adhesion molecules CD11b and L-selectin on airway granulocytes compar ed with blood granulocytes. Objective To investigate whether this modu lation is related to disease activity or due to transendothelial migra tion, we compared the CD11b and L-selectin expression on blood and ind uced sputum eosinophils and neutrophils between patients with asthma a nd normal subjects. Methods Eleven normal subjects (21-43 years), nine patients (21-34 years) with mild atopic asthma and 10 patients (20-47 years) with moderate to severe atopic asthma on regular treatment wit h inhaled steroids underwent sputum induction by inhalation of nebuliz ed hypertonic saline (4.5%). CD11b and L-selectin expression on granul ocytes from blood and DTT-homogenized sputum were analysed by flow cyt ometry. Eosinophils could be discriminated from neutrophils by using d epolarized light scatter. Disease activity was assessed by baseline FE V1 and airway responsiveness to histamine (PC20) Results Sputum eosino phils showed higher expression of CD11b (P<0.001) and lower expression of L-selectin (P<0.001) compared with peripheral blood eosinophils. C D11b and L-selectin expression on eosinophils from blood or sputum did not differ between the three groups. Similar results were obtained fo r neutrophils. The PC20 in the patients with moderate-to-severe asthma was related to CD11b expression on blood (R=-0.92, P = 0.001) and spu tum eosinophils (R = 0.75, P = 0.02). Conclusions Flow cytometry of in duced sputum granulocytes from asthmatic as well as normal subjects is feasible. We conclude that the modulated expression of CD11b and L-se lectin on airway,granulocytes is not specific for asthmatic airway inf lammation, but is probably the result of tissue migration per se. This implies that CD11b and L-selectin expression on granulocytes in induc ed sputum cannot be used as marker of disease activity.