PhotoCatching a cold can be something of a pain for adults who work on a busy schedule, but as you get older it can become a serious medical issue. The human immune system has a tendency to slow down as we age, and its ability to fight viruses, bacteria, and infection becomes seriously hampered as a result.

However, a new study from the University of Arizona Sciences Department of Immunobiology shows that this trend does not necessarily need to be set in stone. The researchers found that stimulating a certain subset of white blood cells may be able to boost the immune system of older individuals and help protect them from pathogens and infection.

Changing T cells

The study focused primarily on one type of T cell – a white blood cell that fights infection – called a naïve T cell. Naïve T cells are different from normal T cells in that they have not yet been exposed to a virus or infection. Because of this, they cannot actively fight a virus or infection, unlike other T cells that are tailored by their interactions to fight certain pathogens.

“When there is an infection, like an influenza virus, for example, a small cohort of these naïve T cells – only those that have special molecules on their surface that will bind to fragments of influenza – are deployed in a very targeted manner,” explains principal investigator Dr. Janko Nikolich-Zugich.

When these naïve T cells are deployed, they change their nature and become effector T cells, which are “armed” to fight. After clearing the virus, many of these T cells end up dying off, but those who don’t stay behind and act as “memory cells” that help fight off the virus if it comes back.

More diversity

While investigating these naïve T cells, the researchers found that they could force them to begin making an anti-viral molecule by stimulating them with pieces of virus. This interaction caused naïve T cells to turn into another sort of memory cell, with the result being that they began to actively fight pathogens in the body.

Specifically, these new cells began attacking cytomegalovirus (CMV) – a virus that nearly everyone is infected with but which is generally only dangerous to those with compromised immune function, such as the elderly. These findings reveal a complexity to naïve cells that scientists were not aware of in the past.

“So our new discovery is that there is more diversity than we realized within naïve cells, and that some have committed to dealing with CMV and other really persistent infections, and others are really, truly naïve,” said Nikolich-Zugich.

Determining level of protection

The next step for the researchers will be trying to figure out how to predict the number of these naïve cells are within the human body. In general, the amount of T cells in a person begins to decline as they age, but these naïve cells may provide a way to protect these individuals from sickness and infection.

“The biggest challenge for us going forward is to measure the status of the immune system, including these new cells, and actually show, in an average person, if you are below a certain level of a T cell population, or a certain cytokine or a certain antibody, what is your risk of infection or poor response to vaccination. And if you are at risk, how can we work to help you and your immune system,” said Nikolich-Zugich.

The full study has been published in the journal Nature Immunology

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