Levels of soluble IL‐2 receptor in plasma from asthmatics. Correlations with blood eosinophilia, lung function, and corticosteroid therapy

SUMMARY Evidence now suggests that cosinophils and T lymphocytes infiltrating bronchial tissues may play a key role in the pathophysiology of asthma. Circulating cosinophils, lung function, and plasma soluble IL‐2 receptor (sIL‐2R) were measured in 42 asthmatic patients referred for symptomatic asthma. The patients were divided into two groups based on the presence or absence of atopy. The group of non‐atopic asthmatics was further divided according to the patients’ requirement for long term oral corticosteroids. The mean sIL‐2R ± s.d. was 36.3 ± 9.9 pM in the control group, 28.9 ± 9.2 pM in the atopic asthmatics, 43.3 ±18.07 pM in the non‐atopic asthmatics without oral steroid therapy, but was increased in the steroid‐treated group (62.2 ±19‐3 pM, P<0.01). A significant correlation was found between I‐FEV 1 and circulating cosinophils in atopic asthmatics and in non‐atopic asthmatics without oral corticosteroid therapy, but not in the steroid‐treated group. Furthermore, significant correlations were found between sIL‐2R and FEV 1 and between sIL‐2R and blood eosinophils, in the group of non‐atopic asthmatics not on oral steroid therapy. No such correlations were evidenced in the other groups of asthmatics. Similar results were obtained during the clinical course of three non‐atopic patients followed for more than I year. These data suggest that T cell activation appears more prominent in non‐atopic asthma than in atopic asthma. Moreover, it appears that T cell activation can occur in severe forms of asthma despite steroid treatment. Finally, the results suggest a possible link between T cell activation, eosinophils. and lung function, which may reflect a particular pathogenetic mechanism involved in non‐atopic asthma.