PTPRC and idiopathic pulmonary fibrosis: To investigate the morphology of blood vessels and the recruitment of neutrophils and macrophages in the lungs of mice with BLM-IPF, we performed immunohistochemical staining for CD31 (endothelial cell marker), MPO (myeloperoxidase, a neutrophil marker), CD86 (macrophage marker), and CD45 (pan-leukocyte marker).