Blood-Based Immune Aging Map Could Help Spot Disease Risk Earlier

Chronological age does not always reflect immune health or future disease risk. Two adults of the same age can have immune systems that age very differently, with some remaining resilient while others develop dysfunctional immune profiles associated with age-related disease. Identifying these divergent trajectories before clinical symptoms emerge remains a challenge.

Researchers at Washington University School of Medicine in St. Louis, working with Nationwide Children’s Hospital and King’s College London, created a map of human immune aging based on differences in immune cell activity. The approach centers on a spectrum defined by the ratio of white blood cells that produce granzyme B to those that produce granzyme K, providing a way to characterize distinct immune aging patterns. The findings were published in Immunity on October 9, 2026.

The method focuses on effector memory CD8 T cells, which use proteins called granzymes to destroy target cells or coordinate immune responses. Granzyme B-producing cells act primarily as direct killers of diseased cells, while granzyme K-producing cells are less well understood and may play a greater role in signaling and recruiting additional immune activity.

To map how these cells change with age, the researchers analyzed approximately 12.4 million individual immune cells from blood samples collected from 2,609 mainly healthy adults ranging in age from 20 to over 90 years. Participants were drawn from eight cohorts across North America, the United Kingdom, Asia, and Australia. Younger participants generally had blood enriched with adaptable naive immune cells, while older immune systems showed greater cellular diversity and, in some cases, increased numbers of inflammation-related immune cells.

The team then examined whether these immune patterns were associated with long-term health outcomes using UK Biobank data from 500,000 initially healthy participants aged 40 to 69 years who were followed for up to 15 years. Because the UK Biobank dataset did not include direct CD8 T-cell counts, the researchers developed a computational model using a smaller dataset that linked CD8 T-cell profiles with blood protein measurements. They then applied the model to baseline blood protein samples from 50,000 UK Biobank participants.

Adults whose immune profiles were more strongly weighted toward granzyme B-producing cells at baseline had a higher risk of death approximately a decade later than those with a greater proportion of granzyme K-producing cells. The granzyme B-dominant group was also more likely to develop chronic conditions, including type 2 diabetes, hypertension, liver disease, and renal failure. 

According to the researchers, placing patients along this immune aging spectrum currently requires complex and costly specialized technology, but work is underway to adapt the approach into a blood test that could be processed using standard laboratory equipment.

“We have found that there are clues in the blood that can tell us whether someone is on a healthy or unhealthy aging trajectory. Identifying specific biological red flags in the immune system could pave the way for early-warning tests that spot disease risks years before a clinical diagnosis,” said Maxim N. Artyomov, Alumni Endowed Professor of Pathology and Immunology at WashU Medicine.

“We can think of it like checking a car's oil level before the check engine light ever turns on. Our goal is to develop an early-warning diagnostic that alerts physicians to subclinical immune stress, prompting more specialized testing that could allow for intervention long before chronic disease symptoms appear,” added Artyomov.

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