Eosinophil activation status and corticosteroid responsiveness in severe asthma

BACKGROUND: Since eosinophils are implicated in asthma pathogenesis, we investigated whether these cells were activated in severe asthma. METHODS: Twenty-six asthmatics with different clinical responses to oral corticosteroid (CS), i.e. sensitive change in forced expiratory volume in 1 s (DeltaFEV(1)) >/= 25% after oral methylprednisolone, 40 mg daily, for 14 days, n = 7], resistant (DeltaFEV(1) /= 20 mg oral prednisone daily for acceptable asthma control, n = 10), were studied. RESULTS: Calcium ionophore-induced leukotriene (LT) C(4) release of purified blood eosinophils was similar in the three groups. Cell incubation with granulocyte-macrophage colony-stimulating factor (GM-CSF) enhanced ionophore-induced LTC(4) release, and this effect was higher in CS-sensitive (5-fold) than in CS-resistant subjects (1.7-fold) (p = 0.02). CS treatment decreased blood eosinophil counts in these two groups of subjects (p