Iron is localized in macrophages in lung of COPD subjects and the percentage of iron positive macrophage increases with severity of disease.

<p>Perls-DAB and CD68 costaining was performed in lung samples obtained from (A–A’) a patient without COPD, (B–B’) a patient with grade 2 COPD and (C–C’) a patient with grade 4 COPD. (D) Percentage of iron positive macrophages was assessed in 8 lungs from subjects without COPD, 9 lungs from subjects with GOLD 2 or 3 COPD and lungs from 20 subjects with GOLD 4 COPD. (E) Correlation between the percentage of iron positive macrophages and the mean radiograph attenuation in the same lung area. *p<0.05 (Anova analysis with a Tukey-Kramer post-hoc test); Scale bars = 125 µm.