Which cells are primarily responsible for mediating immune responses in the brain?

Microglia are the primary immune cells of the central nervous system and play a crucial role in mediating immune responses in the brain. These specialized macrophage-like cells are responsible for monitoring the brain's environment and responding to injury or infection. Microglia continuously survey brain tissue, and when they detect damage or pathogens, they can become activated. Upon activation, microglia can phagocytose debris, release pro-inflammatory cytokines, and present antigens to T cells, enhancing the immune response.

Additionally, microglia have a role in maintaining homeostasis by modulating synaptic connections and supporting neuronal health. Their ability to respond to neuroinflammation and neural injury highlights their significance in the brain's immune defense, distinguishing them from other cell types such as astrocytes, neurons, and oligodendrocytes, which have different primary functions.