Functional Diversity of T-Cell Subpopulations in Subacute and Chronic Hypersensitivity Pneumonitis

Rationale: Hypersensitivity pneumonitis (HP) exhibits a diverse outcome. Patients with acute/subacute HP usually improve, whereas patients with chronic disease often progress to fibrosis. However, the mechanisms underlying this difference are unknown.Objectives: To examine the T-cell profile from patients with subacute HP and chronic HP.Methods: T cells were obtained by bronchoalveolar lavage from 25 patients with subacute HP, 30 patients with chronic HP, and 8 control subjects. T-cell phenotype and functional profile were evaluated by flow cytometry, cytometric bead array, and immunohistochemistry.Measurements and Main Results: Patients with chronic HP showed higher CD4+:CD8+ ratio (median, 3.05; range, 0.3–15; subacute HP: median, 1.3; range, 0.1–10; control: median, 1.3; range, 0.7–2.0; P < 0.01), and a decrease of γδT cells (median, 2.0; range, 0.5–3.4; subacute HP: median, 10; range, 4.8–17; control: median, 15; range, 5–19; P < 0.01). Patients with chronic HP exhibited an increase in the terminally ...