To test this hypothesis, we developed CB201, a fully human anti-CD300c antibody, screened using a synthetic human phage library, and found that monocytes that differentiate to macrophages via CB201 induction can clear Aβ from the brain, and accordingly, administered CB201 to 5xFAD model mice to assess its efficacy in treating AD. This evidence concerns the gene CD300C and Alzheimer disease.