Scientists discover new 'immune hubs' in skull bone marrow

The skull has traditionally been regarded largely as armor for the brain. New research from the United States suggests it may have another role: proactively helping to defend what lies beneath it.

Researchers at Washington University School of Medicine in St. Louis identified previously unknown immune "security stations" in the bone marrow of mouse skulls.

The lymph node-like structures responded to brain tumors before more distant lymph nodes in the neck did. When researchers disrupted the structures in mice with glioblastoma, an aggressive brain cancer , the tumors grew faster and the animals died sooner.

"The skull should no longer be viewed simply as a protective shell around the brain," senior study author Jonathan Kipnis told DW.

"It contains specialized immune environments that appear capable of responding locally to changes within the brain."

The discovery, published in the journal "Nature," comes with an important caveat: The researchers have so far only demonstrated how the structures function in mice, not humans.

Kipnis cautioned that the human evidence remains preliminary: "We found similar immune cells in human skull marrow, suggesting that related structures may exist, but we have not yet demonstrated that they are organized or function in the same way as those in mice," he said.

For much of the 20th century, the brain was described as "immune privileged" — unusually protected from immune activity because inflammation that is useful elsewhere can damage delicate brain tissue.