Eosinophilia in blood and sputum in patients with severe asthma: a preliminary study

<bold>Introduction</bold>: Eosinophils (Eos) in induced sputum (IS) is a marker for the control of severe asthma (SA). Blood Eos count is related to its severity and phenotypes. However, the results in blood and IS are contradictory. The aim of this study is to assess the inflammatory phenotype and its correlation with the level of Eos in IS and blood of SA patients. <bold>Material and methods</bold>: Prospective study with SA patients in whom IS samples were obtained. Level of Eos in blood was quantified. Phenotypes were classified according to the IS results: eosinophilic (>2.5%); neutrophilic (>64%); mixed (Eos >2.5% and neutrophils >64%); and paucigranulocytic (none of them). Blood eosinophilia was considered if patients had >5% Eos. TH1/TH2 response and proinflammatory cytokines in IS were quantified. <bold>Results:</bold> 29 patients were included (10 men, mean age 52 years; 62% non-smokers and 28% ex-smokers). The median (range) Eos in IS and blood were 1.13% (0-46.75) and 3.2% (0.1-16.7) respectively. In IS, the phenotype was eosinophilic in 5 (17%) patients, neutrophilic in 6 (21%) mixed in 5 (17%) and paucigranulocytic in 13 (45%). In blood, 12 (41%) patients presented an eosinophilic phenotype, but only 4 also presented an eosinophilic or mixed phenotype in IS (3 eosinophilic and 1 mixed). Increased G-CSF and IL-1β levels was observed in IS of patients with mixed phenotype compared to the other groups (p < 0.05). <bold>Conclusions:</bold> No correlation was observed between the level of Eos in IS and blood in SA patients. The levels of G-CSF (neutrophilic stimulation) and IL-1β (pro-inflammatory) may indicate a higher inflammation in patients with a mixed phenotype. Funded by Instituto de Salud Carlos III (PI21/01346), FUCAP and SEPAR.