In contrast, Xie et al. reported an increase in CD19+ b lymphocytes in patients with severe and moderate OSA and explained this discrepancy by the fact that the patients recruited for their study did not have severe comorbidities, whereas the patients in the Domagala-Kulawik's study had comorbidities such as obesity, metabolic syndrome and chronic obstructive pulmonary disease (COPD), which may have influenced the expression and differentiation of immune cells such as B lymphocytes. This evidence concerns the gene CD19 and chronic obstructive pulmonary disease.