The number of ICAM–1 positively expressed alveolar macrophages is significantly higher in IPF (median 167,813 cells per mm2, range 56,157–1,209,594 cells per mm2) compared to NC (median 71,714 cells per mm2, range 29,595–56,157 cells per mm2, p = 0.0004) (Figure 4C). This evidence concerns the gene ICAM1 and idiopathic pulmonary fibrosis.