Objective: To test the hypothesis that allergen-specific, steroid-sensitive γδ T lymphocytes are increased in bronchoalveolar lavage fluid of patients with asthma.
Design: Case series.
Setting: The outpatient allergy services at the University of Perugia, Perugia, Italy.
Patients: 12 untreated atopic patients (6 children and 6 adults) with mildly symptomatic chronic asthma were studied. Bronchoalveolar lavage fluid from 10 healthy nonsmoking volunteers and age-matched children with cystic fibrosis (n = 5) or anatomic malformation of the airways (n = 4) served as control samples.
Intervention: Three patients received treatment with deflazacort, 60 mg twice daily, for 1 week.
Measurements: CD3+, CD4+, and CD8+ T cells from patients and controls were examined by two-color flow cytometry for coexpression of Vδ1 and Vδ2 isoforms of the γδ T-cell receptor. In vitro pulmonary γδ 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.
Results: The proportion of γδ 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 γδ CD4+ lymphocytes expressed the γδ T-cell receptor Vδ1 chain. These cells proliferated in response to allergen stimulation, underwent steroid-induced apoptosis in vitro, and disappeared after systemic steroid treatment.
Conclusions: Allergen-specific, steroid-sensitive γδ T cells may be one of the cellular components involved in the airway inflammation that characterizes allergic bronchial asthma.