Brain CD4 T cells and their influence over microglial homeostasis

The brain has a different immune system from the rest of the body, with a unique resident immune cell, the microglia, being the main immune cell type present. As well as their immune surveillance function, microglia are important for aiding the correct wiring of neurons during learning. Microglia are, however, a dual-edge sword, being pathogenic during dementia. We recently identified a novel component to the brain immune system, a type of T cell that transiently migrates from the blood into the brain and triggers the development of foetal microglia. In this programme we will find out how T cells get from the blood into the brain and why they stay there for months at a time. We will also work out the effect that these T cells have on adult microglia during health and the brain inflammatory states associated with dementia, in old age and traumatic brain injury.