Recruitment of CD34+ progenitor cells into peripheral blood and asthma severity.

BACKGROUND: Previous studies have suggested that the number of progenitor cells is elevated in the peripheral blood of asthmatic patients and that the number of progenitors correlate with the severity of the disease.

OBJECTIVE: To evaluate the number of leukocyte progenitor and eosinophil progenitor cells in the peripheral blood of patients with bronchial asthma in relation to disease severity.

METHODS: The study involved 51 patients with asthma (25 patients with a mild form and 26 with a severe form of the disease) and a group of 12 healthy controls. Using the flow cytometric method, leukocyte (CD34+ leukocytes) and eosinophil progenitors (CD34+CD125+) were detected in the peripheral blood of both asthmatic patients and healthy controls.

RESULTS: Patients with asthma had significantly more leukocyte progenitor cells (median, 0.06% vs 0.016%) and eosinophil progenitor cells (median, 0.046% vs 0.004%) compared with the controls. Patients with severe asthma had more leukocyte progenitor cells (0.12% vs 0.035%) and more eosinophil progenitor cells (0.102% vs 0.019%) than patients with mild asthma. The number of circulating leukocyte and eosinophil progenitor cells inversely correlated with the forced expiratory volume in 1 second percentage of predicted value (r = -0.4 and r = -0.35, respectively) and positively correlated (r = 0.63 and r = 0.65, respectively) with the dose of inhaled steroids used to control asthma.

CONCLUSION: These data suggest that the presence of leukocyte precursors and eosinophil progenitor cells in the peripheral blood of asthmatic patients may reflect ongoing airway inflammation.