MOSCOW, July 29:  Russian opposition leader Alexei Navalny was discharged from a hospital Monday even though his physician raised suspicions of a possible poisoning after he suffered facial swelling and a rash while in jail.

The immune system is incredibly important, thanks to its role in fighting off dangerous invaders in our bodies. But sometimes it gets it wrong, targeting harmless proteins from things like nuts or dairy products and triggering allergic reactions that ironically can themselves be fatal. Now, researchers from Michigan State University have identified a mechanism that helps keep the immune system in check, potentially paving the way for drugs that could prevent allergic reactions before they start.