Close-up view of how immune cells kill cancer cells.

Close-up view of how immune cells kill cancer cells.

Our  immune system is constantly on the lookout for cells that are not acting normally.  Changes can occur due to infection with a virus or the conversion of a normal cell to a cancer cell.  Abnormal cells are killed by having holes 'punched' in their membranes.  The proteins that perform this function, perforins, have now been examined at the molecular level, providing a better understanding of the process.  The results should make it easier for researchers to find ways of helping the immune system identify and kill cancer cells that have found ways to avoid detection.