CD4 and chronic obstructive pulmonary disease: As a whole, these results highlight (1) the high heterogeneity in the COPD subpopulation in terms of EP genesis and consequently CD4+ T-cell dependent IL-4 expression; (2) the interest to evaluate IL-4 in circulating T-cells to better characterize COPD inflammatory phenotypes and to develop further studies to precise the putative role of EP to favour an IL-4-dependent anti-inflammatory response in COPD patients.