The shorter the telomeres, the weaker the immune system
The shorter the telomeres, the weaker the immune system
Some immune cells act like the body's special forces, fighting off viral infections. These immune cells are called T cells. These cells differentiate and form in the thymus gland below the sternum, and as they mature, they leave the thymus and circulate throughout the body.
Each T-cell has a unique receptor on its surface, which acts like the searchlight of a police helicopter, scour the body for "prisoners" -- cells that have become infected or cancerous. (One type of T cell in particular is associated with aging: CD8 cells.)
To do the job, T cells must receive a second signal from a surface protein (CD28), a green light that signals an immune response. After T cells destroy the target, T cells will have "memory", the same virus will invade the body in the future, T cells will reproduce thousands of cells and their own daughters, play a strong immune response, quickly destroy that virus. This is the basis of vaccination.
A vaccine is usually a viral protein or fragment of a virus that has been killed, and the immune effect lasts for many years, because The T-cells that respond to the initial vaccination can survive for a long time (sometimes for a lifetime) and then go out and destroy the virus once it invades again.
We have many different types of T cells, each of which can recognize an antigen or a virus. So when we are infected with a virus, a few T cells with the right receptor can multiply to fight the virus. For T cells to keep dividing, to make lots of them, they need lots of telomerase. However, if the rate of telomere shortening is too fast to replenish, the telomerase reaction will become weaker and the telomeres in T cells will become shorter and shorter. If the T cells' telomeres are too short, they age, lose their surface marker, CD28, and are unable to mount an effective immune response.
At this point, the body is like a financially strapped city with no budget for police helicopters and searchlights. Although the city looks fine on the outside, there will be more and more delinquents. Bacteria, viruses and cancerous cells cannot be removed from the body. This is why people with aging cells (including the elderly and those with chronic stress problems) are more likely to get sick and catch the flu or pneumonia. This is one of the causes of the disease in people with HIV.
Once T cells age, telomeres become too short, making it easy for even young people to get sick. Cohen, a psychologist at Carnegie Mellon University, recruited young people to live in single rooms in hotels and infect them with the cold virus.
He then measured their telomeres. He found that immune cells with shorter telomeres, especially CD8 cells that were about to age, developed cold symptoms faster and more severe (as measured by toilet paper they had used for sneezing and runny noses, and by weighing themselves).
The ideas shared here come from the Telomere Effect, a book by Nobel Laureate Elizabeth Blackburn.