Dynamics of blood and sputum eosinophils in asthma patients with cold airway hyperresponsiveness during cold air provocation

<b>Background:</b> According to GINA, 63.8% of asthma patients have an eosinophilic pattern of airway inflammation (sputum eosinophils ≥3%). We aimed to assess the cell inflammatory pattern change in asthmatics with cold airway hyperresponsiveness (CAHR) in response to acute cold exposure. <b>Methods:</b> In 33 patients with CAHR induced sputum (IS) was collected, the next day the test with 3-minute isocapnic hyperventilation with cold air (IHCA) was performed, after which spontaneously produced sputum was collected. The cells percentage in sputum cytograms was determined. The absolute and relative eosinophil numbers in the peripheral blood were assessed. <b>Results:</b> Two groups were formed by IS pattern: 1st group (n=11) with non-eosinophilic (1.8±0.23% of eosinophils; 55.3±3.8% of neutrophils) and 2nd group (n=22) with eosinophilic (15.6±2.0% of eosinophils, p=0.00014; 41.0±2.9% of neutrophils, p=0.003) pattern of airway inflammation. The groups had no differences in FEV1 (90.5±2.7 vs. 91.7±2.3%) and asthma control (16.7±1.9 vs. 15.1±1.2 ACT points, p&gt;0.05). The fall of FEV1 in response to IHCA was in averaged -16.8±2.0 vs. -19.1±1.6%, respectively. A significant increase of eosinophils in sputum after IHCA till 18.1±7.6% (p&lt;0.01) was observed in the 1st group, while in the 2nd group there was no dynamics (13.8±1.7%; p&gt;0.05). Eosinophils in the peripheral blood did not have significant inter-group differences: absolute cell number was 172.0±17.1 vs. 217.4±22.6 per 100 cells; the relative one was 2.6±0.74 vs. 3.6±0.83%. <b>Conclusion:</b> In asthmatics with CAHR and non-eosinophilic inflammatory pattern, an acute cold exposure leads to an increase of sputum eosinophils.