Blocking Immune T Cells Protects Brain Tissue in Alzheimer's — Without Removing Toxic Protein

Researchers at Washington University in St. Louis published a study in the journal Neuron in October 2026 showing that the immune system — not just the accumulation of toxic tau protein — is a major driver of neurodegeneration in Alzheimer's disease and related tauopathies. The team found that T cells, a type of immune cell, infiltrate brain tissue in response to tau build-up and attack neurons. By administering an antibody that blocks CXCR3, a protein on the surface of T cells that guides them into the brain, the researchers reduced T-cell infiltration by roughly half in mice with tau pathology. The result was striking: the treated mice preserved approximately 40% more brain tissue in memory centres and performed significantly better on memory tasks, even though the tau burden itself was not reduced. The finding matters because most Alzheimer's drug strategies have targeted either amyloid plaques or tau tangles, with limited success. This research suggests that interrupting the immune-cell attack on neurons could be an independent and complementary therapeutic avenue. An additional practical advantage is that the antibody acts on T cells in the bloodstream before they cross into the brain, potentially side-stepping the blood-brain barrier challenges that have hampered many neurological therapies. Senior author Dr. David M. Holtzman said the results warranted pursuit of clinical development.