A standard industrial cooling step accidentally turns a "go" signal for the immune system into a "stop" signal.

IVIg therapy is a common treatment for immune disorders, but why it works has been poorly understood. Researchers found that the cold ethanol used during manufacturing changes the fundamental message of IFN-gamma proteins. These molecules usually tell the immune system to attack, but the process transforms them into suppressors that calm the system down. This accidental discovery explains why the treatment is so effective at stopping cytokine storms and inflammation. It highlights how the way we manufacture medicines can be just as important as the ingredients themselves.