Killer cells may help reduce effects of colitis

An immune-system cell long considered the bully on the block turns out to have a soft side, actually helping reduce inflammation. The discovery opens the possibility of new treatments for inflammatory bowel disease.

Natural killer cells are white blood cells that are on constant patrol, watching for any signs of infection or tumour cells. If found, the killer cells move in immediately to wipe out the invader, said Dr Silvia Melgar, a faculty investigator in University College Cork's alimentary pharmabiotic centre.

The scientists assumed that mice with inflammatory bowel disease such as colitis might have milder symptoms if they did not have killer cells. They tested this theory on a mouse that had no killer cells, but the opposite happened: inflammation increased.

Details of the Science Foundation Ireland-funded research are published in the Nature journal Mucosal Immunology.

“These cells were going to be the bad guys in the story. Instead, what we saw was when the cells were not there, the animals got worse colitis.”

When the killer cells were allowed back in, inflammation was reduced, a sign that the killer cells were somehow working against the colitis symptoms.

"Our findings open up the possibility of new therapeutic approaches for IBD and other inflammatory diseases such as cystic fibrosis, rheumatoid arthritis and severe asthma," said Dr Lindsay Hall, first author of the study.