Relationship between induced sputum cell counts and fluid-phase eosinophil cationic protein and clinical or physiologic profiles in mild asthma

Are sputum eosinophil cationic protein and eosinophils differently associated with clinical and functional findings of asthma?

“…According to these results, we might speculate that the symptomatic phases of the disease (‘active phases’) are associated with the recruitment of activated eosinophils (high sputum eosinophil counts and ECP levels) in the airways, whereas with the progression of the disease (long asthma duration and remodelling development), the number of eosinophils may decrease while still remaining strongly activated, thus explaining high ECP levels. In our study, changes in the pattern of airway inflammation with the increase in duration of disease were confirmed by the direct relationship between sputum neutrophil counts and asthma duration, as already reported , and between sputum neutrophil counts and ECP concentrations.…”

“…In a study comparing the relationship of blood and sputum eosinophils and ECP with clinical and functional indices of asthma severity, only sputum eosinophils and ECP were found to correlate with symptom score, spirometry and airway hyperresponsiveness, with stronger correlations for eosinophils than for ECP [12]; furthermore, although sputum ECP was reported to be a more sensitive marker of airway inflammation and asthma severity than serum ECP and blood eosinophils, the authors, however, concluded that sputum ECP adds no clinically important information to the results obtained with sputum eosinophils. On the other hand, some authors reported data suggesting that ECP may correlate better than eosinophils with pulmonary function and/or bronchial hyperresponsiveness, at least in subgroups of asthmatic patients [9], whereas others reported that both sputum eosinophils and ECP correlated with parameters of airway obstruction [12,28,29]. The discrepancy among these results might be explained by differences in the number of patients studied, in the levels of asthma severity, in the effects of inhaled corticosteroid treatment.…”

“…One study showed that both sputum eosinophils and ECP correlate with airway hyperresponsiveness in asthmatic patients , whereas Gutierrez et al. reported that only sputum eosinophil counts were inversely correlated with PC 20 ‐methacholine in mild asthmatic patients. In a study comparing the relationship of blood and sputum eosinophils and ECP with clinical and functional indices of asthma severity, only sputum eosinophils and ECP were found to correlate with symptom score, spirometry and airway hyperresponsiveness, with stronger correlations for eosinophils than for ECP ; furthermore, although sputum ECP was reported to be a more sensitive marker of airway inflammation and asthma severity than serum ECP and blood eosinophils, the authors, however, concluded that sputum ECP adds no clinically important information to the results obtained with sputum eosinophils.…”

Full blood count parameters for the detection of asthma inflammatory phenotypes

“…One study did not use sputum to evaluate the airway eosinophilia but biopsy specimens and did not control for oral corticosteroid use. Another study found a non‐significant trend between peripheral blood and sputum eosinophil counts ( r = 0.34, P = 0.067), but the sample size was only 31 patients and so may have been underpowered .…”

Airway responsiveness to hypertonic saline: dose-response slope or PD15?

“…Since airway responsiveness below the level of AHR was only associated with asthma symptoms, it is suggested that airway responsiveness to hypertonic saline also reflects longer-term airway abnormalities. Other explanations may be a lack of sensitivity for blood eosinophilic markers to detect bronchial inflammation [23], or the possibility that airway responsiveness and eosinophilic activation represent different inflammatory pathways [24,25].…”