Antibodies Produced by the Human Immune System Are Typically Prevented

Antibodies produced by the human immune system are typically prevented from getting to the brain by the blood‒brain barrier.Does this mean that the brain has no immune defenses?

A) No, microglia in the brain and spinal cord provide an immune function.
B) No, astrocytes carry out an immune function in addition to their other functions.
C) No, macrophages from the general circulation cross the blood‒brain barrier.
D) Yes, but there is no need for immune defenses in the central nervous system, since the blood‒brain barrier also protects it from infection.
E) Yes, this is why infections of the brain are so common.