Similar with results observed in metabolic diseases (23, 34, 38), our data revealed that circulating MAIT cell deficiency was accompanied by upregulation of HLA-DR, and CCR5 expression, indicating that reduction in MAIT cell numbers in peripheral blood of COPD patients might be due partly to the migration of MAIT cells to inflamed tissues. This evidence concerns the gene CCR5 and chronic obstructive pulmonary disease.