CD8A and chronic obstructive pulmonary disease: In particular, moderate but significant univariate correlations were found between the Forced Expiratory Volume in 1 s/Forced Vital Capacity (FEV1/FVC) ratio (used to diagnose COPD if below 0.7), and the density of fibrocytes, the density of interacting cells, the mean minimal distance between fibrocytes and CD8+ T cells and the density of fibrocytes-CD8+ T cells clusters (Figure 1—figure supplement 4A–D).