Scientists have discovered a new "organ" hidden in the skull

Biologists at Washington University School of Medicine in St. Louis have discovered previously unknown immune structures inside the skull bones of mice. The researchers suggest that such an "organ" may also be present in humans, helping the immune system recognize and attack brain tumors. The results of the study have been published in the journal Nature.

The unusual structures were discovered by scientists in the bone marrow of mouse skulls. They turned out to resemble germinal centers — areas of the lymphatic system where immune B cells undergo "training" and begin to develop defenses against specific threats.

The discovery was made possible by previous research from the same scientific group. The scientists had identified small channels that pass from brain tissue through the dura mater directly into the skull bones. In the new study, using fluorescent markers, they traced the movement of molecules through these channels and discovered a connection between the brain and immune structures in the bone marrow.

The researchers named the discovered formations localized lymphoid structures. Their location may be of significant importance: the immune cells are situated directly adjacent to the brain and are capable of rapidly responding to pathological processes occurring within it.

To verify the role of these structures, the scientists conducted experiments on mice with glioma — an aggressive brain tumor. When the activity of the discovered immune formations was suppressed, tumors developed faster and the animals' lifespan was shortened. Conversely, stimulation of these structures using three immunoactive proteins enhanced the anti-tumor response and increased survival rates in mice.

For now, scientists cannot say with certainty that the same system exists in humans. However, follicular T cells have previously been found in the bone marrow of the human skull, which may indicate the presence of analogous immune structures. If the existence of this mechanism in humans is confirmed, the discovery could lead to a new approach to treating brain diseases without direct intervention in the tissue.