Luka Cicin-Sain: “The immune response becomes inefficient with age”
In the coronavirus pandemic, older people are particularly at risk from severe courses of COVID-19. However, other infectious diseases also affect them more than younger people. On the occasion of the International Day of Older People on 1 October, Prof Luka Cicin-Sain, Head of the Department „Viral Immunology“ at Helmholtz Centre for Infection Research (HZI) in Braunschweig, talks about the ageing of the immune system.
Like most organs in the body, the immune system ages. How does this change the immune system’s ability to fight off infections and respond to vaccinations?
Our body continuously renews itself through the activity of stem cells. These provide a supply of new cells in all organ systems. Stem cells constantly multiply, the daughter cells mature and become, for example, blood cells, bone cells and skin cells. However, over the decades, the number of stem cells in our body declines and the ability to renew decreases: We grow old. Thus, ageing is essentially determined by the loss of stem cells. This particularly affects the immune system, where white blood cells are constantly renewed.
Lymphocytes are a subgroup of white blood cells and they are the basis of the adaptive immune response. In our body, there is an enormous variety of lymphocytes that can recognise millions of different molecules of infectious agents, the so-called antigens. Through stem cells, the lymphocytes constantly renew themselves. However, as we age, this function diminishes and our immune system recognises fewer and fewer antigens. This means that an immune response becomes inefficient in old age – against both vaccines and infections.
Older people have already experienced numerous infections in their lives and have built up an immune memory against many pathogens. Why are they still often more severely affected by infectious diseases? Is the ability to recognise and ward off new pathogens „used up“ at some point?
The immune memory against pathogens that older people encountered in their youth may well remain intact in old age. It is rather the ability to recognise new pathogens and antigens that is affected. However, the recognition of new pathogens is not in competition with memory. These are two functions performed by two different groups of cells: The naïve cells are responsible for recognising new pathogens and the memory cells recognise the previously-encountered pathogens. The problem is rather that too few new naïve cells are created, and not that the already acquired immune memory takes away their place.
You can find the complete interview on our homepage under the link https://www.helmholtz-hzi.de/en/news-events/interview/luka-cicin-sain-the-immune-response-becomes-inefficient-with-age/
Helmholtz Centre for Infection Research:
Scientists at the Helmholtz Centre for Infection Research (HZI) in Braunschweig and its other sites in Germany are engaged in the study of bacterial and viral infections and the body’s defence mechanisms. They have a profound expertise in natural compound research and its exploitation as a valuable source for novel anti-infectives. As member of the Helmholtz Association and the German Center for Infection Research (DZIF) the HZI performs translational research laying the ground for the development of new treatments and vaccines against infectious diseases. www.helmholtz-hzi.de/en