Blood gas analysis indexes, forced expiratory volume in first second (FEV1 Studies show that impaired immunologic tolerance play an important role in pathogenesis of COPD,7,8 and COPD exacerbation and RF are associated with the imbalance of circulating CD4+ T cell subsets, more specifically, T-helper 1 and 2 (Th1/Th2) ratio.1-4 The balance of Th1/Th2 cells plays an important role in allergy and autoimmune diseases. Here, CD4 is linked to chronic obstructive pulmonary disease.