Researchers from the University of Virginia School of Medicine say they’ve found compelling evidence that social interactions are influenced by the immune system.

Researchers from the University of Virginia School of Medicine say they’ve found compelling evidence that social interactions are influenced by the immune system. 
When battling pathogens, a molecule called interferon gamma is released to keep any number of viruses, parasites, and bacteria in check. 
Previous research indicates the immune system delivers doses of the molecule during social interactions as well, likely due to the pathogen-spreading opportunities such encounters create. 
In recent experiments, scientists decided to investigate what would happen if interferon gamma was removed from the equation entirely and ended up with some rather interesting results. 
According to the study, "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."
The researchers concluded that interferon gamma fills a, “…profound role in maintaining proper social function.”