Anatomy Question

Likely obvious to a skilled professional, I am trying to learn, I have the following question based upon reading an anatomy textbook.

Question – Autoimmune diseases caused by white blood cells attack myelination creating inflammation in Multiple Sclerosis yet white blood cells can’t cross BBB (Blood Brain Barrier). Is it the Microglia (Resident Macrophages) that attack the myelination?

“Multiple sclerosis (MS) is one such disease. It is an example of an autoimmune disease. The antibodies produced
by lymphocytes (a type of white blood cell) mark myelin as something that should not be in the body. This causes
inflammation and the destruction of the myelin in the central nervous system. As the insulation around the axons is
destroyed by the disease, scarring becomes obvious. This is where the name of the disease comes from; sclerosis means
hardening of tissue, which is what a scar is. Multiple scars are found in the white matter of the brain and spinal cord.
The symptoms of MS include both somatic and autonomic deficits. Control of the musculature is compromised, as is
control of organs such as the bladder” – Anatomy and Physiology Volume 2 Open Stax

“Like a few other parts of the body, the brain has a privileged blood supply. Very little can pass through by diffusion.
Most substances that cross the wall of a blood vessel into the CNS must do so through an active transport process. Because
of this, only specific types of molecules can enter the CNS. Glucose—the primary energy source—is allowed, as are amino
acids. Water and some other small particles, like gases and ions, can enter. But most everything else cannot, including white
blood cells, which are one of the body’s main lines of defense. While this barrier protects the CNS from exposure to toxic
or pathogenic substances, it also keeps out the cells that could protect the brain and spinal cord from disease and damage.
The BBB also makes it harder for pharmaceuticals to be developed that can affect the nervous system. Aside from finding
efficacious substances, the means of delivery is also crucial.” – Anatomy and Physiology Volume 2 Open Stax

“Microglia are, as the name implies, smaller than most of the other glial cells. Ongoing research into these cells,
although not entirely conclusive, suggests that they may originate as white blood cells, called macrophages, that become
part of the CNS during early development. While their origin is not conclusively determined, their function is related to
what macrophages do in the rest of the body. When macrophages encounter diseased or damaged cells in the rest of the
body, they ingest and digest those cells or the pathogens that cause disease. Microglia are the cells in the CNS that can do
this in normal, healthy tissue, and they are therefore also referred to as CNS-resident macrophages.” – Anatomy and Physiology Volume 2 Open Stax