A CONVENIENT type of killer white blood cell could make organ rejection a thing of the past.

The cells suppress the immune response in the livers of mice, without affecting the rest of the immune system. Humans have this type of blood cell, so it might be possible to create immune-tolerant organs for transplant.

Marta Monteiro and colleagues at the University of Lisbon, Portugal, studied mice protected from the animal equivalent of multiple sclerosis by natural killer T-cells (NKT), a class of white blood cell which helps to control the immune system.

They discovered a population of NKT cells that …