Immune cells have been discovered to play a surprising role in helping neurons send messages from the brain to the body. From Osaka University, scientists show how the immune system’s involvement in nerve propagation may have applications to neurological disorders like autism, schizophrenia, and multiple sclerosis.
Scientists previously thought that T and B cells could not cross into the brain tissue via the blood brain barrier. Apparently that’s not the case.
“Our study suggests otherwise, though, as we found that a certain type of B cell is quite abundant in the ventricles, meninges, and choroid plexus in the brains of young mice,” explained lead author Shogo Tanabe. “Even more surprising, these cells appear to stimulate axon myelination in the surrounding neurons."
T cell research links this immune cell to learning and memory function in the meninges, but this is the first study to place B cells in the brain, aiding in myelin production during early development.
The myelin sheath is a plasma membrane wrapped around a nerve to insulate the electrical messages that pass through neurons. Myelin is produced by cells other than the actual neurons the myelin sheath wraps itself around - cells called oligodendrocytes.
In a new study, researchers found that a specific type of B cells, called B-1a cells, regulate the number of oligodendrocytes as the brain develops and produces myelin to cover neurons. Researchers also saw that when young mice lacked adequate B-1a cells in the brain, oligodendrocyte levels dropped drastically.
"Our findings provide direct evidence that B cells reside in the mouse neonatal brain and promote both oligodendrocyte proliferation and neuron myelination,” explained lead investigator Toshihide Yamashita. “This suggests to us that B cell dysfunction in early development may contribute to later mental disorders, a possibility that we believe deserves further exploration in future studies."
"It turns out that so-called natural antibodies secreted by B-1a cells induce oligodendrocyte precursors to proliferate,” Tanabe explained. “These antibodies are typically involved in immune surveillance, but in this case they promote the myelination of axons."
The present study was published in the journal Nature Neuroscience.
Sources: Basic Neurochemistry: Molecular, Cellular and Medical Aspects. 6th edition; Osaka University
