In the early neuroprotective stage of AD, the accumulation of amyloid-β enhances the binding of the astrocyte-derived cytokine interleukin-3 (IL-3) to its receptor, interleukin-3 receptor alpha chain (IL-3Rα), on the microglial membrane, thereby activating signaling mediated by triggering receptor expressed on myeloid cells 2 (TREM2). This evidence concerns the gene TREM2 and Alzheimer disease.