CD74 and Alzheimer disease: In addition, the expression of the antigen recognition ligand CD74 secreted by macrophages and the corresponding receptors MIF (Migration Inhibitory Factor), APP (Amyloid Beta Precursor Protein), and COPA (COPI Coat Complex Subunit Alpha) in endothelial cells was significantly higher in AD tissues than in normal tissues (Figure 4E and Supplementary Figure S2E).