Researchers discovered lymph node-like immune hubs inside skull bone marrow that appear to act as rapid-response centers for the brain.

For decades, the brain was thought to operate largely apart from the immune system. Researchers at Washington University School of Medicine in St. Louis have now identified lymph node-like structures inside the skull bone marrow of mice that respond rapidly to brain cancer, before more distant lymph nodes receive signals that abnormal cells are present. They also found evidence of similar immune cells in human skull bone marrow.

The findings add to growing evidence that the brain communicates directly with the immune system and suggest that specialized immune centers are positioned unusually close to the organ they help protect.