There are at least 2 major subsets of macrophages; classically activated (M1) macrophages stimulated by Th1-type responses and alternatively activated (M2) macrophages stimulated by Th2-type responses.32.M2 macrophages scavenge debris and contribute to angiogenesis, suppression of adaptive immunity, wound healing and fibrosis by producing IL-10 and CCL18.33 Murthy et al34 found that alveolar macrophages from patients with asbestos-induced pulmonary fibrosis showed high expression levels of MARCO. This evidence concerns the gene CCL18 and pulmonary fibrosis.