The way T cells respond to viruses and vaccines changes with age: this transformation affects the production of antibodies.
Why is the immune system’s response to vaccines generally weaker in older adults, the people who most need protection against infections? Research published in Nature has found an answer that in the future could help us create vaccines that are more effective and better suited to mature immune systems.
A different way of responding to threats (real or perceived)
T lymphocytes, i.e. white blood cells that recognize foreign substances (antigens) presented by other cells, have a key role in coordinating the immune response: among their tasks is in fact that of instructing B lymphocytes on the production of antibodies in response to viruses or vaccines.
A group of scientists from the Allen Institute in Seattle (Washington) has discovered that, as we age, the T lymphocytes of each of us undergo a profound transformation, which substantially alters the response of these cells to dangers: the way in which they react to threats changes – real, constituted for example by viruses, or “implants”, such as the viral components introduced specifically by vaccines to stimulate an immune response.
A normal consequence of age
To be more precise, what changes is gene expression, that is, the process in which the genetic information present in DNA is translated into molecules. The effects of all this weaken the memory of T lymphocytes; as a result, B cells struggle to produce as robust an amount of antibodies as they did in the past.
It may therefore happen that, even if the influenza vaccine is adapted to the viral strain circulating in that season, the B cells of elderly patients respond less effectively than those of younger ones.
These alterations do not depend on pathological aspects linked to advancing age, such as inflammatory processes, but are part of healthy physiological aging of all organisms.
A map of the immune system
To arrive at this discovery, scientists used cutting-edge techniques to observe how the immune profile of 96 adults between the ages of 25 and 65, followed for over two years, changed over time. Starting from this data they created a map of the changes in 71 different types of immune cells, which they made available to the scientific community (it is called the Human Immune Health Atlas, and can be freely consulted). Finally, they used this map to study over 16 million immune cells taken from healthy adults, aged 25 to over 90 years of age.
In the future: more effective vaccines
This new knowledge of how the immune system changes could help us develop vaccines with a more personalized approach suitable for advanced age, which take into account how cells age, or to imagine therapies to combine with vaccines that improve the immune response.
Allowing cells to react as they once did.
