Consistently, in this much larger cohort using a CD4+ T cells to APCs ratio (10:1), we found a strong positive correlation between the production of IFN-γ (r = 0.59, P < 0.0001) and IL-6 (r = 0.58, P < 0.0001), and the severity of emphysema as determined by quantitative CT scan (Figures 2A,B). This evidence concerns the gene CD4 and pulmonary emphysema.