Measurement of soluble perforin, a marker of CD8+ T lymphocyte activation in epithelial lining fluid.

Background: CD8(+) T lymphocytes in the peripheral airways have been suggested to be involved in the pathogenesis of COPD. However, the significance of CD8(+) T lymphocyte activation in COPD is not well understood. A biomarker of CD8(+) T lymphocyte activation in patients with COPD is required.