Background: T lymphocytes (predominantly CD8+ cells) have previously been implicated in the pathogenesis of chronic obstructive pulmonary disease (COPD).
Objective: We sought to describe the profile of cytokine production by CD8+ and CD4+ cells isolated from bronchoalveolar lavage fluid.
Methods: Bronchoalveolar lavage was performed in 11 patients with COPD (median FEV1, 63.3% of predicted value) and 9 healthy control subjects. CD8+ and CD4+ T cells were isolated by means of positive selection after macrophage depletion. CD8+ and CD4+ cells were activated with anti-CD3/CD28 antibodies for 60 hours before restimulation with phorbol 12-myristate 13-acetate-ionomycin and brefeldin. Three-color flow cytometry was used to simultaneously measure levels of intracellular cytokines.
Results: IL-4 was expressed by a higher percentage of stimulated CD8+ T cells (TC2) compared with CD4+ T cells (TH2) in patients with COPD (P = .01). In contrast, IFN-gamma was expressed in a significantly higher percentage of stimulated CD4+ T cells (TH1) than CD8+ T cells (TC1) in the COPD group (P = .04). TNF-alpha was expressed by almost all TC1 and TH1 cells, with virtually no expression by TC2 and TH2 cells. In addition, a small number of T cells expressing TNF-alpha alone without concomitant IFN-gamma or IL-4 expression were seen in the majority of subjects. There was a higher percentage of TC2 cells in subjects with COPD compared with that seen in the control group (P = .03). Stimulation with anti-CD3/CD28 antibodies increased the percentage of TC2 cells and decreased the percentage of TH2 cells.
Conclusion: Our results suggest that there are increased numbers of TC2-like cytokine-expressing cells in the lungs of patients with COPD.
Clinical implications: These cells might be a source of TH2 cytokines, which might, at least in part, explain the lung eosinophilia associated with COPD exacerbations.