CD8A and chronic obstructive pulmonary disease: Therefore, in the present study, in order to evaluate immune responses, the authors investigated the percentages of CD4+ T-lymphocytes, CD8+ T-lymphocytes and the ratio of CD4+ and CD8+ T-lymphocytes in peripheral blood, and further evaluated concentrations of interferon-γ, soluble interleukin-2 receptor,interleukin-6,tumor necrosis factor-α in serum from TB patients with or without COPD and healthy volunteers.