CD4 and chronic obstructive pulmonary disease: The content of lymphocytes with cytotoxic function (CD3+CD8+) in absolute values was prevalent in COPD patients compared with control group and patients with asthma (p1-2 = 0.000440, p2-3 = 0.000010) that affected the immunoregulatory index (CD4+/CD8+), which was increased to the value of 2.4 standard units (p1-2 = 0.008355, p2-3 = 0.000030, and p2-4 = 0.0000132).