Methods: We enrolled 51 adult stable asthmatic patients who had been treated with ICS for more than 3 months. Analysis of induced sputum, blood test, pulmonary function test, FeNO measurement, and Asthma Control Test (ACT) were carried out. The percentages of basophils and CD203c expression on basophils in sputum and blood were examined by a flow cytometer.
Results: Forty-four sputum samples were analyzed. Basophils were detected as CD45+ FceRIhi SIRP-alo CD123hi c-kit- cells or CD45+ CD203c+ SIRP-alo CD123hi HLA-DR- cells in sputum of stable asthmatic patients. The percentages of sputum basophils were correlated with those of eosinophils and mast cells (r=0.765, P<0.001 and r=0.581, P<0.001 respectively). CD203c expression was significantly increased on sputum basophils as compared with that on peripheral blood basophils (92.9±44.6 vs 40.5±31.1, P<0.01).
Conclusions: Basophils were activated and increased in airways of eosinophilic asthmatic patients. Those findings suggest sputum basophils could be a biomarker as well as a therapeutic target of eosinophilic asthma.