Ethnic differences in immune response to TB bacterium

04 July 2013

Tuberculosis, X-ray

Image: Coloured X-ray of the chest of a male patient with pulmonary tuberculosis (TB).©  GUSTOIMAGES/SCIENCE PHOTO LIBRARY

The immune response to the bacterium that causes tuberculosis (TB) varies between patients of different ethnic origins, according to new research from the MRC's National Institute of Medical Research (NIMR; now part of the Francis Crick Institute) and Queen Mary, University of London.

The findings raise important implications for the development of tests to diagnose and monitor treatment for the disease.

TB is an infection caused by the bacterium Mycobacterium tuberculosis. It commonly affects the lungs. While the number of cases reduced in the UK due to BCG (TB) vaccination, improvements in living standards and the introduction of effective antibiotic treatment, it has been on the increase since the late 1980s. TB also remains a major global health problem, with nearly 9 million new cases and 1.4 million deaths in 2011.

Led by Adrian Martineau at NIMR and Queen Mary University of London, the researchers analysed the immune response of 128 newly-diagnosed TB patients in London who were divided by ethnicity into those of African (45), European (27), Asian (55) or mixed European/Asian (1) ancestry.

By analysing the levels of various inflammatory markers in blood samples taken before treatment, the scientists showed that immune responses of Asians and Europeans were similar to each other, but different from those of Africans. This difference was caused by ethnic variation in the patients' genetic make-up: it was not related to the strain of TB bacterium that the patients were infected with.

Dr Martineau said: "The TB bacterium has co-evolved with humans following migration to Europe and Asia some 70,000 years ago, and different strains of the TB bacterium disproportionately infect particular ethnic groups. Our study has shown, for the first time, that it is ethnic differences in the patient's genetic make-up that cause most of the variation in immune responses - with little effect of the TB strain they are infected with."

Dr Anna Coussens, who measured immune responses in patient samples at the NIMR, added: "These findings have important implications, both for the development of new diagnostic tests, which increasingly rely on analysing the immune response, and also for work to identify candidate biomarkers to measure response to anti-TB treatment. In the future, diagnostic tests and biomarkers will need to be validated in different ethnic populations."

The paper, Ethnic variation in inflammatory profile in tuberculosis, is published in PLOS Pathogens.

  • Scientists at the MRC's National Institute of Medical Research have helped to show that there are ethnic differences in the immune response to the bacterium that causes tuberculosis (TB).
  • The results have implications for the development of diagnostic tests and for research into ways to measure patient responses to treatment.
  • The work was funded by the British Lung Foundation and the MRC.