In a startling discovery that raises fundamental questions about human behavior, researchers at the University of Virginia School of Medicine have determined that the immune system directly affects -- and even controls -- creatures' social behavior, such as their desire to interact with others. So could immune system problems contribute to an inability to have normal social interactions? The answer appears to be yes, and that finding could have great implications for neurological conditions such as autism-spectrum disorders and schizophrenia.
"The brain and the adaptive immune system were thought to be isolated from each other, and any immune activity in the brain was perceived as sign of a pathology. And now, not only are we showing that they are closely interacting, but some of our behavior traits might have evolved because of our immune response to pathogens," explained Jonathan Kipnis, PhD, chairman of UVA's Department of Neuroscience. "It's crazy, but maybe we are just multicellular battlefields for two ancient forces: pathogens and the immune system. Part of our personality may actually be dictated by the immune system."
It was only last year that Kipnis, the director of UVA's Center for Brain Immunology and Glia, and his team discovered that meningeal vessels directly link the brain with the lymphatic system. That overturned decades of textbook teaching that the brain was "immune privileged," lacking a direct connection to the immune system. The discovery opened the door for entirely new ways of thinking about how the brain and the immune system interact.
The follow-up finding is equally illuminating, shedding light on both the workings of the brain and on evolution itself. ...
The UVA researchers have shown that a specific immune molecule, interferon gamma, seems to be critical for social behavior and that a variety of creatures, such as flies, zebrafish, mice and rats, activate interferon gamma responses when they are social. Normally, this molecule is produced by the immune system in response to bacteria, viruses or parasites. Blocking the molecule in mice using genetic modification made regions of the brain hyperactive, causing the mice to become less social. Restoring the molecule restored the brain connectivity and behavior to normal. In a paper outlining their findings, the researchers note the immune molecule plays a "profound role in maintaining proper social function."...
https://www.sciencedaily.com/releases/2016/07/160713143156.htm