Serum Levels of Soluble Interleukin–2 Receptor at Acute Asthma Exacerbation: Relationship with Severity of Exacerbation and Bronchodilator Response

Abstract

Background: T lymphocytes play a central role in the regulation of airway inflammation in asthma, and T cell activation appears to be a characteristic feature of acute asthma. It is not clear, however, whether this is proportional to the severity of acute asthma and is directly related to airway inflammation relevant to airflow obstruction during acute asthma. It is presumed that the extent to which bronchoconstriction or inflammation contributes to airflow obstruction in acute asthma may determine responsiveness to bronchodilator therapy. Methods: Fifty asthmatic children who visited the emergency room due to acute exacerbation were studied. Serum levels of soluble interleukin–2 receptor (sIL–2R), a marker of T cell activation, were measured at the time of acute exacerbation and of clinical remission. At acute exacerbation, FEV₁ was assessed before and after the administration of aerosolized salbutamol. Results: The mean (±SD) serum level of sIL–2R at acute exacerbation (854±248 U/ml) was significantly higher (p<0.01) than at clinical remission (676±211 U/ml). It correlated positively with the severity of exacerbation (r = 0.47, p<0.01), but showed no significant relationship with bronchodilator response (r = –0.17, p = 0.20). Conclusion: A higher serum level of sIL–2R at acute exacerbation was associated with more severe exacerbation but not with lower bronchodilator response. These findings suggest that in the context of acute asthma, T cell activation is proportional to disease activity, but its relationship to airway inflammation relevant to the genesis of airflow obstruction remains obscure.

Measurement of Inflammatory Mediators of Eosinophils and Lymphocytes in Blood in Acute Asthma: Serum Levels of ECP Influence the Bronchodilator Response

“…We took great care with the collecting and processing of blood samples. Our findings expand on the results of previous studies [24, 46]by showing not only that serum levels of sIL-2R at acute exacerbation were significantly higher than the internal control, but also that the levels correlated positively with the severity of bronchoconstriction. However, levels of serum sIL-2R did not correlate significantly with the degree of responsiveness to bronchodilator therapy at acute exacerbation.…”

“…Several studies have demonstrated that serum levels of sIL-2R are elevated in patients with asthma [15, 44, 45, 46]. It is not clear, however, whether the levels increase further during acute asthma [24, 44].…”

Reply

“…Matsumoto et al [6] also have shown that serum sIL-2R was elevated in asthmatics compared with normal control subjects. Although the comparison of sIL-2R between asthmatic and normal subjects was not a scope of our study [1], the increase in serum sIL-2R levels in asthmatic subjects compared with normal subjects may be one evidence that T cell activation is present in asthmatics.…”