Increased Allergen-Specific, Steroid-Sensitive γδ T Cells in Bronchoalveolar Lavage Fluid from Patients with Asthma

Abstract

To test the hypothesis that allergen-specific, steroid-sensitive gamma delta T lymphocytes are increased in bronchoalveolar lavage fluid of patients with asthma. Case series. The outpatient allergy services at the University of Perugia, Perugia, Italy. 12 untreated atopic patients (6 children and 6 adults) with mildly symptomatic chronic asthma were studied. Bronchoalveolar lavage fluid from 10 healthy non-smoking volunteers and age-matched children with cystic fibrosis (n = 5) or anatomic malformation of the airways (n = 4) served as control samples. Three patients received treatment with deflazacort, 60 mg twice daily, for 1 week. CD3+, CD4+, and CD8+ T cells from patients and controls were examined by two-color flow cytometry for coexpression of V delta 1 and V delta 2 isoforms of the gamma delta T-cell receptor. In vitro pulmonary gamma delta T-cell proliferation in response to a specific allergen, the apoptotic death of these cells after incubation with 10(-7) M dexamethasone, and bronchoalveolar lavage fluid T-lymphocyte composition before and after 1 week of deflazacort therapy were evaluated in 3 Dermatophagoides pteronyssinus-sensitive patients. The proportion of gamma delta T lymphocytes, primarily CD4+ or CD4- CD8- cells, was higher in asthmatic patients than in controls (P < 0.05 by one-way analysis of variance). Most lung gamma delta CD4+ lymphocytes expressed the gamma delta T-cell receptor V delta 1 chain. These cells proliferated in response to allergen stimulation, underwent steroid-induced apoptosis in vitro, and disappeared after systemic steroid treatment. Allergen-specific, steroid-sensitive gamma delta T cells may be one of the cellular components involved in the airway inflammation that characterizes allergic bronchial asthma.