Which cell type in the nervous system is primarily responsible for immune responses?

Microglia are specialized cells in the nervous system that play a crucial role in immune responses. They act as the primary immune defense in the central nervous system (CNS), constantly monitoring the environment for signs of injury or disease. When activated, microglia can migrate to sites of damage, where they perform several important functions, including phagocytosis of debris and pathogens, releasing inflammatory mediators, and helping to modulate the repair processes. This ability to respond to changes in the CNS makes microglia essential for maintaining homeostasis and responding to neurological diseases.

Astrocytes, while involved in various supportive roles in the brain, such as maintaining blood-brain barrier integrity and modulating neurotransmitter levels, do not primarily function as immune cells. Schwann cells are responsible for myelination in the peripheral nervous system, and oligodendrocytes serve a similar purpose in the CNS but do not have roles in immune responses. Therefore, microglia stand out as the key players in the immune landscape of the nervous system.