An immune molecule that helps defend people from infection with viruses or bacteria may also keep brain activity in check, allowing people to be social. The preliminary findings, presented today at the
2015 Society for Neuroscience annual meeting in Chicago, show that
brain exposure to interferon-gamma — a molecule released in response to infection — is necessary for normal social behavior in mice.
The findings add an intriguing new layer to the link between the immune system and the brain. They suggest that conditions characterized by social deficits, such as autism, could stem in part from a faulty immune system, says lead researcher
Jonathan Kipnis, professor of neuroscience at the University of Virginia in Charlottesville.
“We are showing a very clear immune molecule that is important for immune function and that also works in the brain on social behavior,” Kipnis says. “We’re leaving behind the perception that the brain and immune system are completely separate and [that] neuroscience is for neuroscientists and immunology for immunologists.”
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That the same molecule might work to fight off infection and induce people to be more social may not be as surprising as it seems at first glance. Over the course of evolution, once animals started gathering in large groups they would have also needed a way to ward off contagious infections, says Filiano. “When organisms aggregate, there’s a better chance they could spread virus,” he says.
