The interstitium fibrosis, collagen, elastic, and smooth muscle elements; architectural remodeling, and chronic interstitial inflammation with variable increases in lymphocytes, neutrophils, plasma cells, macrophages, eosinophils, and mast cells; CD4-, CD8-, CD11b-, and CD18-positive cells; hyperplasia of type II cells; and hyperplasia of endothelial cells are common pathologic features in IPF. Here, CD4 is linked to idiopathic pulmonary fibrosis.