As a type of immune cell, it has always been considered one of the good guys. But in a stunning breakthrough in schizophrenia research, scientists say the "macrophage" immune cell can go rogue, causing havoc in the brain.

"Macrophage" means "big eaters" in Greek and is a fitting name for the cell because - when behaving - it digests cellular debris and foreign substances.

Australian researchers have, for the first time, identified the presence of macrophage cells in the brain tissue of a subgroup of people with schizophrenia.

"It's like a murder mystery, one that’s remained unsolved for a hundred years," Professor Cyndi Shannon Weickert from Neuroscience Research Australia (NeuRA) said.