Bronchial exudate of serum proteins during asthma attack

OBJECTIVE: Although altered vascular permeability and edema of the bronchial mucosa are associated with asthma attack, their influence on its severity remains unknown. We address this issue by comparing relative indices for the concentration of albumin (RIAlb) and α2-macroglobulin (RIα2M) in induced sputum and peripheral blood from patients with exacerbated asthma, patients with stable asthma, and control subjects. PATIENTS AND METHODS: Forty-six volunteers participated in the study: 14 with exacerbated asthma (forced expiratory volume in the first second [FEV 1] 743% [SD, 20.8%] of reference), 23 with stable asthma (FEV 1 93.6% [7.5%]), and 9 controls (FEV1 101.1% [9.9%]). The concentrations of albumin and α2-macroglobulin were quantified by immunoturbidimetry and immunonephelometry, respectively. The relative index was then calculated by dividing the concentration in sputum supernatant by the concentration in peripheral blood. RESULTS: The mean RIAlb was 1.2 (1.1) in the control group, 2.9 (3.1) in the stable asthma group, and 6.0 (6.7) in the exacerbated asthma group. The RIα2M values were 11.7 (10.9), 11.9 (14.7), and 3.2 (3.8) for the control group and stable and exacerbated asthma groups, respectively. The increases in the RIAlb values between all groups, and the decrease in the RIα2M value between the exacerbated asthma and control groups were statistically significant (P<.05). The percentage of neutrophils, but not of eosinophils, in sputum was correlated with the RIAlb (r=0.39; P=.008) but not the RIα2M (r=-0.035; P=.82). FEV1 displayed an inverse relationship with the RIAlb (r=-0.43; P=.009) but not with the RIα2M (r=-0.206; P=.24). No correlation was found between oxyhemoglobin saturation and either the RIAlb (r=-0.33; P=.19) or the RIα2M (r=-0.12; P=.84). CONCLUSIONS: Vascular permeability is altered during asthma exacerbations and appears to be correlated with the presence of neutrophils and the degree of bronchial obstruction.