Sydney team develops new blood test

Scientists in Sydney have developed a new blood test to detect regulatory T cells, a subset of white cells that protect against the development of autoimmune and inflammatory diseases such as type I diabetes, multiple sclerosis, Crohn's disease and ulcerative colitis.

Using flow cytometry, collaborators at the Centenary Institute, the Centre for Immunology and the University of Sydney's Department of Paediatrics believe that the blood test is a world first.

"The problem is that the markers [regulatory T cells] express on their surface are a little bit different in humans and until now people haven't really been able to accurately identify them," said Centenary Institute's Assoc Prof Barbara Fazekas de St Groth. "What we've done is actually hunt through a lot of different markers and find the combination that really pulls them out of the very distinct population."

Regulatory T cells are believed to prevent the immune system from attacking itself. Patients with inflammatory bowel disease, such as Crohn's disease and colitis, produce only about half the number of regulatory T cells as compared with controls.

"Currently it is believed that the hygienic living conditions in the west have paradoxically allowed the immune system, which should be focused on responding to viruses, bacteria and parasites, to turn inward and attack the body itself," Fazekas de St Groth said.

She said inflammatory and autoimmune diseases were becoming more common every year with up to 10 per cent of people having an autoimmune disease, at least 25 per cent of preschool children having asthma and probably 40-50 per cent of the adult community having some sort of allergy.

"We've got rid of our infectious diseases, but at the same time we've inadvertently increased the incidence of all these other diseases," she said. "Somehow we're going to have to work out how to get rid of this new set of diseases without exposing ourselves to the old set that we've been trying to get rid of."

As well as Crohn's disease and colitis, the test will be used to look at diseases such as asthma and diabetes and will hopefully lead to a better understanding as to why these diseases are increasing in Australia and the rest of the western world.

Using only four monoclonal antibodies, the new blood test takes about an hour to complete. "It's quick and easy, very simple," said Fazekas de St Groth.

At the moment the test is only available for research. If the test is commercialised it would probably be through medical technology company Becton Dickinson, which has an exclusive worldwide license over the test's provisional patent for the next 12 months. "After that we'll assess what happens," said Fazekas de St Groth.

The research findings were presented at the Australasian Society for Immunology's annual scientific meeting, held in Melbourne last week.