Stimulating immunity:
Dr. Brent Johnston looks to Natural Killer T cells in the fight against cancer
Natural Killer T cells could be powerful natural allies in the body's efforts to fight cancer. They just need a bit of prompting, according to Dr. Brent Johnston, Canada Research Chair in Inflammation and Immunity at Dalhousie Medical School.
“Natural Killer T cells are a rare population of white blood cells that have the potential to fight infections and cancers,” says Dr. Johnston, who joined Dalhousie in 2004 from Stanford University. “Once activated, the NKT cells can set off an aggressive immune response against tumour cells. The challenge then is to direct that response to the primary tumour’s specific location.” With funding from the Canadian Cancer Society, Dr. Johnston is exploring ways to do both. He’s studying how signalling proteins and receptors can be manipulated to stimulate NKT cells and attract them to tumour sites.
An expert in immune-system function, Dr. Johnston is also studying white blood cells known as gamma delta T cells. These important cells bridge the gap between the body’s non-specific innate defence systems, and the specific immunity we acquire after exposure to germs. They may play a crucial role in the defence against Pseudomonas, a lung infection that commonly afflicts people with cystic fibrosis.
Dr. Johnston’s interests also extend to autoimmune diseases, with a focus on the mechanisms behind rheumatoid arthritis. “In rheumatoid arthritis, signalling proteins called chemokines inappropriately signal white blood cells to migrate to healthy tissues,” he explains. “This triggers a vicious circle of damage and inflammation.” He wants to learn what initiates these faulty signals, so he can find molecules that will turn them off.
In essence, Brent Johnston works on both sides of the immunity coin. “Cancer and autoimmune disease are becoming ever more common…we must find ways to both ramp up and tone down the immune response to prevent sickness and disability.”