IL2 and Alzheimer disease: As in humans, FK506 accumulated in the brain and prevented or attenuated many AD pathologies including neuroinflammation, increased cytokine production, synaptic loss, and cognitive impairment and, importantly, did so without substantially affecting peripheral immune cell function as assessed by mitogen-induced, IL-2 mRNA expression from peripheral blood mononuclear cells (PBMC) harvested during therapy or splenocytes, harvested at euthanasia.