Immunohistochemically stained activated eosinophils in sputum in patients with asthma.

BACKGROUND

Eosinophils play an important role in asthmatic airway inflammation. Monoclonal antibody EG2 has been considered to identify activated eosinophils.

OBJECTIVE

The present study was aimed to investigate whether immunohistochemically stained EG2+ eosinophils in sputum reflect the severity of asthma.

METHODS

Sputum was obtained in 23 asthmatic patients, of whom 13 patients were examined before and after antiasthma treatment including steroid preparations. We used immunohistochemical staining to detect EG2+ (activation marker) eosinophils and fluoroimmunoassay to detect eosinophil cationic protein (ECP).

RESULTS

Moderate to severe asthmatics had a significantly higher proportion of eosinophils and EG2+ eosinophils and higher levels of ECP compared to mild asthmatics (40.9 +/- 5.8 vs. 6.4 +/- 1.2%, 35.5 +/- 5.6 vs. 2.7 +/- 1.0%, 1.470.2 +/- 251.5 vs. 210.6 +/- 52.0 microgram/l, respectively; p < 0.01). Significant increases in proportions of eosinophils, EG2+ eosinophils and ECP in the sputum from patients with exacerbated asthma were evident. The proportions of eosinophils, EG2+ eosinophils, and the levels of ECP were reduced following treatment with antiasthmatic drugs. FEV(1) and FEV(1)/FVC were significantly correlated with EG2+ eosinophils.

CONCLUSION

These findings demonstrate that EG2+ eosinophils in sputum are closely related to the clinical status in patients with asthma.