Mechanism Found to Temporarily Reverse Aging in the Immune System

The research has created an avenue to temporarily reverse the effects of aging on immunity and could, in the future, allow for the short-term boost of the immune systems of older individuals.

The study’s findings were published in the September 2011 issue of the Journal of Immunology. Weakened immunity is a serious issue for older people. Because immune systems become less effective as one ages, people suffer from more infections and these are often more severe, taking a serious toll on health and quality of life.

Prof. Arne Akbar, from University College London (UCL; UK), who led this research, explained, “Our immune systems get progressively weaker as we age because each time we recover from an infection a proportion of our white blood cells become deactivated. This is an important process that has probably evolved to prevent certain cancers, but as the proportion of inactive cells builds up over time, our defenses become weakened. What this research shows is that some of these cells are being actively switched off in our bodies by a mechanism, which hadn’t been identified before as important in aging in the immune system. Whilst we wouldn’t want to reactivate these cells permanently, we have an idea now of how to wake them from their slumber temporarily, just to give the immune system a little boost.”

Until now, aging in immune cells was thought to be largely determined by the length of specific caps on the ends of DNA. These caps, called telomeres, get shorter each time a white blood cell multiplies until, when they get too short, the cell is permanently deactivated. This means that our immune cells have a built-in lifespan of effectiveness and, as we live longer, this no longer long enough to provide us protection into old age.

However, when Prof. Akbar’s team took some blood samples and looked closely at the white blood cells they saw that some were inactive and yet had long telomeres. This told the researchers that there must be another mechanism in the immune system causing cells to become deactivated that was independent of telomere length. Prof. Akbar noted, “Finding that these inactive cells had long telomeres was really exciting as it meant that they might not be permanently deactivated. It was like a football manager finding out that some star players who everyone thought had retired for good could be coaxed back to play in one last important game.”

When the researchers blocked this newly identified pathway in the laboratory, they discovered that the white blood cells appeared to be reactivated. Pharmaceutical agents that block this pathway are already being developed and tested for use in other treatments so the next phase in this research is to explore further whether white blood cells could be reactivated in older individuals, and what benefits this could bring.

Prof. Akbar continued, “This research opens up the exciting possibility of giving older people’s immune systems a temporary boost to help them fight off infections, but this is not a fountain of eternal youth. It is perfectly normal for our immune systems to become less effective and there are good evolutionary reasons for this. We’re a long way from having enough understanding of ageing to consider permanently rejuvenating white blood cells, if it is even possible.”

Prof. Douglas Kell, chief executive of the Biotechnology and Biological Sciences Research Council (BBSR; Swindon, Wiltshire, UK), the organization that funded the research, said, “This is a fantastic example of the value of deepening our understanding of fundamental cell biology. This work has discovered a new and unforeseen process controlling how our immune systems change, as we get older. Also, by exploring in detail how our cells work, it has opened up the prospect of helping older people’s immune systems using medicines that are already being tested and developed. By increasing the incidence and severity of infection, weakened immunity seriously damages the health and quality of life of older people so this research is very valuable.”

Related Links:
University College London
Biotechnology and Biological Sciences Research Council