TNF and chronic obstructive pulmonary disease: CD8+ lymphocyte, macrophage and neutrophil levels have been demonstrated to increase in bronchial biopsy tissue, while IL-8, IL-6, tumor necrosis factor-α (TNF-α) and their soluble receptor levels have been demonstrated to increase significantly in the circulation and airducts of patients with COPD in flatland areas, indicating that persistent chronic inflammation is present in COPD (19).