BAL eosinophil counts and specific clinical phenotypes of asthmatic and/or atopic children

Eosinophils play an important role in the inflammatory process of asthma and allergy, but their role is still unclear. This study aimed to investigate whether BAL eosinophils could identify specific clinical phenotypes of asthmatic and/or atopic children. We analysed BAL and bronchial biopsies from 107 children undergoing fiberoptic bronchoscopy for appropriate indications: 26 atopic asthmatics (AAS), 28 non-atopic asthmatics (NAAS), 22 atopics without asthma (ANAS) and 31 non-asthmatic non-atopic controls (C). Total and differential cell counts, ECP and IL-8 were analysed in BAL. Inflammatory cells were also quantified in bronchial biopsies by immunohistochemistry. Based on BAL counts we grouped children into non-eosinophilic (BAL eos ≤1%; 90 children: 16 AAS, 24 NAAS, 20 ANAS, 30 C) and eosinophilic (BAL eos ≥2%; 17 children: 10 AAS, 4 NAAS, 2 ANAS, 1 C). Age was similar in the two groups (median 5 yrs). Eosinophilic children showed significant increases in IgE, ECP, IL8, BAL neutrophils and tissue eosinophils (p<0.01 for all). When the eosinophilic group was divided in intermediate (2% ≤ BAL eos <4%) and severe (BAL eos ≥4%), both groups had increased IgE, ECP and tissue eosinophils. Instead, IL8 and neutrophil counts were increased in intermediate but not in the severe group (p<0.005). Severe eosinophilia was seen more frequently in children with difficult asthma (p=0.039). In conclusion, BAL eosinophilia in our study was observed in 15,8% of children and severe eosinophilia in 7.5%. AAS were more frequent in the intermediate and severe eosinophillic groups; NAAS were equally distributed in the three groups and ANAS were present in the non-eosinophilic and severe eosinophilic group.