CD4 T-lymphocyte activation is associated with peak expiratory flow variability in childhood asthma

Background: Asthma has been recognized as a chronic inflammatory disorder of the airway. We have investigated the relationships among the activation markers on lymphocytes, eosinophils, their serum products in the peripheral blood, and the variability of airway obstruction in childhood asthma. Methods: Twenty-two patients with atopic asthma (mean age, 12 years) were treated regularly and asked to measure their peak expiratory flow (PEF) twice daily for 7 days. Peripheral venous blood was obtained on day 8. Results: The absolute counts of CD4 T lymphocytes expressing the activation marker CD25 in the peripheral blood or day 8 correlated significantly with the values of the coefficient of variation (CV) of both morning PEF (p < 0.01) and night PEF (p < 0.05) obtained over 7 days, but those of CD8+/CD25+ T lymphocytes, those of CD23+ B lymphocytes, and the serum concentrations of soluble CD25 did not. The absolute counts of peripheral blood eosinophils also demonstrated a significant correlation with the CV values of both morning PEF (p < 0.01) and night PEF (p < 0.05). Conclusion: CD4 T-lymphocyte activation and increased counts of eosinophils in peripheral blood correlate with CV of PEF is patients with asthma, suggesting that CV of PEF is a good marker for assessing not only die variability of airway obstruction but also the degree of airway inflammation.