In order to experimentally address these hypotheses, we ablated microglia cells from 12-month-old WT and APP-PS1 transgenic mice for 4 weeks using the colony stimulating factor 1 receptor (CSF1R) inhibitor PLX5622 and analyzed its consequences on behavior, on amyloid plaque pathology, on the recruitment of peripheral immune cells from the innate and adaptive immune system, i.e. macrophages and T-cells, and on the expression of typical pro-inflammatory, anti-inflammatory, and phagocytosis specific-genes. This evidence concerns the gene PSEN1 and amyloidosis.