Leukocyte infiltration patterns and structural changes in severe asthmatics with variable degree of clinical control

Results In the comparison between stable SA and symptomatic SA, stable SA was associated with higher levels of eosinophils (p<0.05), T-helper type-2 cells (p<0.05) and macrophages (p<0.01). The remaining cell types analysed; T-helper cells, T-cytotoxic cells, B-cells, natural killer cells, neutrophils, basophils and mast cells tended to be lower in symptomatic SA compared with stable SA, although no statistical significance was found. Comparing the two SA groups with healthy controls, stable SA was associated with significantly increased levels of several leukocyte populations whereas symptomatic SA was not. Interestingly, both SA groups were characterized by a significant epithelial metaplasia as compared with healthy control subjects. Reticular basement membrane thickness and airway smooth muscle mass was similar between all three groups, although some patients in the SA groups had high levels. Within the SA group (n=25), a significant correlation was found between FEV1/FVC and the expression of myosin light chain kinase in the airway smooth muscle mass (r=0.66 and p<0.001). The two SA groups were matched in terms of gender, age (median 51, p=1.0) years), BMI (median 28.4, p=0.3), FEV1/FVC (median 0.67, p=0.2), dose of oral corticosteroids (median 15 mg/d, p=0.8) and duration of disease (median 16 years, p=0.9).