CD68 and chronic obstructive pulmonary disease: As COPD is a chronic airway inflammatory disease characterized by the infiltration of CD8+ T lymphocytes and CD68+ macrophages (42), we concluded that the differences in CD8+ T lymphocytes and CD68+ macrophages between the two groups may have been caused by COPD itself, suggesting that the existence of COPD is an important factor for the benefit of immunotherapy.