UNIVERSITY OF BIRMINGHAM NEWS RELEASE –
Ill health may not be an inevitable part of getting older A common virus causes our immune system to work overtime as we get older
A new study has uncovered changes to our immune systems which may explain why we become more vulnerable to common infections as we get older.
Research from the University of Birmingham has shown that as we age greater numbers of helper T-Cells, which play a key role in directing the immune system, become sidelined in responding to the CMV virus, which is normally harmless. The study, which was funded by the Medical Research Council is published in the Journal of Virology.
Cytomegalovirus, or CMV, is a Herpes virus, which infects around 7 in 10 people in the UK. In most healthy individuals the virus remains dormant, without causing any symptoms, although it is a serious health problem amongst patients with compromised immune systems.
Lead author Professor
Paul Moss explains
: “By studying the levels of T-Helper cells that respond to CMV in different age groups we were able to examine how the body’s immune response to the virus changed over time. The level of the T-Cell response to CMV in our elderly donors was disproportionately high. This suggests that the virus is actually having a much more negative impact by taking up an increasing amount of the body’s immune capacity.” The researchers from the university’s Institute for Cancer Studies analysed the levels of T helper cells that were activated in response to the CMV virus in blood samples from a group of 40 healthy donors aged 60 and over. These volunteers were members of the "The Thousand Elders Panel", a nationwide group, which was set up by the university’s Centre for Applied Gerontology to help investigate the needs of older people. They then compared these levels with similar samples from a group of 30 younger volunteers (aged under 40).
They found that the number of T-Cells responding to the CMV virus was more than twice as high in the older group. On average nearly 6% of their total CD4-T Cell response was directed at CMV compared to only 2.3% in the younger group.
Professor Moss continues: “The results were very striking: in the older donors the number of CMV specific T-Cells was more than double that in the younger group. In a significant number of our elderly donors the response to CMV was far above the average, in one person up to a third of the total T-Cell response was activated by CMV. Traditionally CMV has been seen as a harmless virus, because it doesn’t produce symptoms in most healthy people. However, this study backs up the evidence that CMV may have a malign impact on our immune systems as we get older, eating up valuable resources that could be directed elsewhere.”
The study also showed that donors infected with CMV had fewer T helper cells that were capable of responding to newly encountered pathogens. This further suggests that the presence of CMV in the body compromises the immune system.
Dr Laxman Nayak from the University’s Centre for Applied Gerontology, which works to promote awareness of the needs of older people adds: “We know that elderly people are more vulnerable to a range of infectious diseases, without knowing exactly why. It is very good to see that in recent years there has been more research to explain the biological processes at work, as this opens up the possibility of treatments to boost immunity. These kinds of findings also send out the message that we shouldn’t accept that ill health is an inevitable part of getting older.”
ENDS The full title of the paper is: The CMV-specific CD4+ T cell response expands with age and markedly alters the CD4+ T cell repertoire
Batoul Pourgheysari, Naeem Khan, Donna Best, Rachel Bruton, Laxman Nayak and Paul A.H. Moss – it is published in the Journal of Virology
For further information contact: Ben Hill, Press Officer, University of Birmingham, Tel 0121 414 5134, 07789 921 163.
NOTES TO EDITORS CMV
Cytomegalovirus (CMV), is a member of Herpes family of viruses; in humans the species is known as Human herpesvirus 5 (HHV-5). CMV, is a very common virus, which infects a large percentage of the population. It is thought that the percentage of the population infected is between 50 and 80%. Once a person becomes infected, the virus latently persists in the body throughout their life. In the general population, CMV rarely produces symptoms. However, the virus can also be life threatening for patients who are immunocompromised particularly patients with HIV, organ transplant recipients and newly born babies
T-helper cells
T helper cells are a sub-group of lymphocytes (a type of white blood cell ) that plays an important role in establishing and maximizing the capabilities of the immune system. These cells do not play a role in killing infected host cells or pathogens. Their key role is in activating and directing other immune cells. They have a role in the activation and growth of cytotoxic T cells, and in maximizing bactericidal activity of phagocytes such as macrophages. It is this diversity in function and their role in influencing other cells that gives T helper cells their name. Mature T helper cells are believed to always express the surface protein CD4. T cells expressing CD4 are also known as CD4+ T cells.
Medical Research Council
The Medical Research Council is dedicated to improving human health through excellent science. It invests on behalf of the UK taxpayer. Its work ranges from molecular level science to public health research, carried out in universities, hospitals and a network of its own units and institutes. The MRC liaises with the Health Departments, the National Health Service and industry to take account of the public’s needs. The results have led to some of the most significant discoveries in medical science and benefited the health and wealth of millions of people in the UK and around the world. www.mrc.ac.uk
