Lung macrophages: old hands required rather than new blood?

Comparisons to normal lung tissue obtained from cancer resections, suggest that there is no significant difference in the total number of macrophages in transplanted lung tissue across the 2 years. [...]while there was a large amount of inter-individual variation the abundance of donor-derived macrophages was largely unchanged over the follow-up period. Macrophage numbers are increased in lung tissue taken from patients with COPD and the number of airways containing macrophages increases in line with disease severity. 5 While numbers are increased, there are reports of macrophages being less mature in COPD in terms of both size 6 and surface marker expression. 7 Taken together with the increased expression of the chemokine monocyte chemoattractant protein-1 (CCL2) described in the COPD airway, 8 these observations suggest that monocytes may be recruited to the COPD airway.