An Algorithm for Immunological Age and Disease

Your age does not determine how healthy you are or how long you are going to live for.

Scientists from the Stanford School of Medicine and the Buck Institute for Research on Aging have found a way to calculate the age of your immune system, what they’re calling “iAge” or an inflammatory clock. The study’s results were published in July 2021 in Nature Aging.

Your iAge score may be a better predictor of your health than your chronological age in years. This new method allows doctors to determine how soon a person will experience age-related changes, which opens the door for early detection and intervention to help minimize the effects of age-related changes in susceptible individuals.

Further, the iAge tool could lead to new interventions targeted at increasing healthspan. It works by sum-totaling the amount of chronic inflammation in a person’s body, and at a biological level, inflammation can be traced to our immune systems.

Immunology 101

A healthy immune system protects the body from harm. Having a strong immune system increases resilience to help the body fight back against illness and germs.

It is often activated by antigens, which are foreign substances not recognized by the immune system as a part of the body. When they attach to receptors on cells in the immune system, the body responds.

When the body first encounters an antigen, it studies and remembers the germ to learn how to fight it. The immune system is constantly developing and adapting as new germs and diseases enter the body.

That’s why having a strong immune system is vital to maintaining health. Without a strong immune system, there would be no way to:

  • Fight disease-causing germs, like bacteria, viruses, parasites, or fungi and remove them from the body.
  • Recognize and neutralize harmful substances from the environment.
  • Respond to disease-causing changes in the body, such as cancer cells.

As we age, our immune systems naturally start to decline in function, and the more reduced its function becomes, the more susceptible we are to disease.


Immune systems can respond the same way they do to antigens, even when they are not supposed to. This means that the body is defending against cells that are meant to be present in the body.

When the immune system experiences inflammation over a long period of time, it can lead to health problems, such as heart disease, arthritis, depression, Alzheimer’s disease, and in some cases, cancer.

Older adults are more likely to experience the effects of inflammation and weak immune system health, increasing the likelihood of these health problems.

Therefore, the development of iAge is pivotal to understanding how to prevent immune system decline. Here’s the science behind it:


The Stanford 1000 Immunomes Project collected blood samples from 1,001 subjects between the ages of 8 and 96 years of age in a nine-year longitudinal study.

Researchers measured levels of the CXCL9 cytokine, a protein present in the immune system released by certain cells that help fight infection. This cytokine was the main player in determining an individual’s iAge score, among about 50 other cytokines involved in the process.

CXCL9 has been known to impair the function of endothelial cells, which help regulate blood flow. Past research has shown that damaged endothelial cells are the precursors of cardiovascular disease.

After age 60, levels of CXCL9 increased at the site of infection, raising the amount of inflammation these adults experienced, and putting them more at risk of illness. This suggests that reducing levels of CXCL9 could result in less inflammation and lower risk of disease.

To turn these observations into a neat, single score, researchers employed an artificial intelligence algorithm to analyze CXCL9 and the 50 other cytokines implicated in iAge.

iAge could lead to early interventions into disease and could contribute to a more graceful aging process. While you may not be able to figure out your own iAge score, it is important to take care of and support your immune system.

Immune System Health

The best way to protect your immune system is to live healthy, which includes everything you’ve probably already been told to do, such as:

  • Don’t smoke.
  • Eat fruits and vegetables.
  • Exercise regularly.
  • Maintain a healthy weight.
  • Drink alcohol in moderation.
  • Get enough sleep.
  • Maintain your hygiene.
  • Minimize stress.
  • Keep up with recommended vaccines.

Each of these contribute to keeping your immune system healthy while researchers continue to develop the iAge technology to better understand how the immune system plays a role in living a healthy life.

For related blogs, visit this one about “Inflammaging: The Side Effect of Age You Haven’t Heard Of,” or this one about your biological vs. chronological age.

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Grace Weintrob is a junior majoring in Communication Studies with a minor in Stage, Sports, and Film Production at CSU. She is currently working as the digital media intern for the Columbine Health Systems Center for Healthy Aging.