The immune system may not only be guarding our physical health, but our mental health as well. Experts led by Yale University came to this conclusion while they compared immune system cells in the spinal fluid of MS patients and healthy subjects.
In the spinal fluid of healthy patients, the team discovered an inflammatory autoimmune response that is typically associated with neurodegenerative diseases such as multiple sclerosis (MS).
The findings support an emerging theory that gamma interferons, a type of immune cell that helps induce and modulate a variety of immune system responses, may also help to prevent depression in healthy people.
“We were surprised that normal spinal fluid would be so interesting,” said study senior author Professor David Hafler.
Previous studies have shown that blocking gamma interferons, along with the T cells they help produce, can cause depressive symptoms in mice. Professor Hafler noted that depression is also a common side effect in patients with MS treated with a different type of interferon.
The investigation was made possible through a powerful new technique which allows individual cells to be examined in great detail. Using this technology, the researchers determined that while the characteristics of T cells in the spinal fluid of healthy people share similarities with those of MS patients, they lack the ability to replicate and cause the damaging inflammatory immune system response seen in autoimmune diseases such as MS.
In the brain of all people, the immune system is prepared to make an inflammatory response and may have another function than defending against pathogens, said Professor Hafler. “These T cells serve another purpose and we speculate that they may help preserve our mental health.”
According to Professor Hafler, his lab and colleagues at Yale plan to explore how immune system responses in the central nervous system may affect psychiatric disorders such as depression.
The study is published in the journal Science Immunology.