This CIRM grant allowed my group to translate findings from our Alzheimer’s research from mouse to man. Over several years my group, an others, showed that boosting T cell responses to a peptide found in the plaques of Alzheimer’s patients could reduce disease pathology and memory problems in mouse models of this disease. Interestingly, at least some people carry T cells in their immune system, but it was unknown who has them or if they are lost over the course of Alzheimer’s disease. In this CIRM-funded project we used stem cells to develop a new technology, called CD4see, to identify and quantify those T cells using a small sample of human blood, roughly the same amount taken for a standard blood panel. After years of development and testing of CD4see, we used it to look for and quantify those plaque-specific T cells in over 70 human subjects. We found an age-dependent decline of Aβ-specific CD4+ T cells that occurred earlier in women than in men. Men showed a 50% decline around the age of 70, but women reached the same level before the age of 60. Notably, women who carried the AD risk marker apolipoproteinE-ε4 (ApoE4) showed the earliest decline, with a precipitous drop that coincided with an age when menopause usually begins. This assay requires a sample of whole blood that is similar to standard blood panels, making it suitable as a routine test to evaluate adaptive immunity to Aβ in at-risk individuals as an early diagnostic test for Alzheimer’s disease. In future applications CD4see can be used to isolate those cells in the lab, expand them to millions of cells, and then return them back to the same person–our earlier mouse studies showed those T cells counter Alzheimer’s pathology and memory impairment, so this technology may lead to a new therapeutic approach. I am grateful to CIRM and California taxpayers for supporting young scientists and funding innovative research.