A Map of 1.2 Million Cells Reveals Diversity Across Asia
A study of more than 1.2 million immune cells from 625 healthy donors has found that differences among Asian ethnicities can be as pronounced as those between men and women. The findings could change how researchers design drug trials and how doctors interpret blood tests across the region.
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Led by the Agency for Science, Technology and Research (A*Star) in Singapore, the international research brought together scientists from Singapore, Thailand, Korea, Japan and India. Their study, published in the journal Cell in March 2025, produced the Asian Immune Diversity Atlas (AIDA), the most comprehensive map of immune cell diversity in Asia to date.
The researchers examined donors from seven population groups across five Asian countries. Their central finding is that treating Asian populations as biologically interchangeable can overlook substantial differences in immune cells, the cells that help the body respond to disease.
Age, sex and diversity within Asia all affected immune cell traits. Those differences matter because medical tests and treatment research often depend on knowing what is typical in a healthy person before identifying what has changed during illness.
Why Drug Trials Need Broader Representation
Biomedical research has historically focused heavily on European populations. Diagnostic tools and treatment guidelines developed from that research may therefore fail to account for biological characteristics found in other ethnic groups.
Dr. Shyam Prabhakar, the study's senior author and associate director at A*Star Genome Institute of Singapore, compared the need for ethnic diversity in research with the established practice of including both men and women in drug trials.
It is well established that you have to have men and women in your cohort for drug trials because we understand this biological difference. The data is suggesting the same applies to ethnicity. You cannot do your drug trial on one ethnicity and say the results apply to all.
His point concerns who is represented when medical evidence is gathered. If a trial studies only one ethnic group, differences in immune biology may affect how well its findings apply to people outside that group.
For patients, the concern is practical: tests and treatment decisions based on an incomplete picture of human biology may be less accurate or less effective for some populations. The study argues for wider participation in research so that medical advances can benefit people beyond the groups most often studied.
What the Researchers Measured
The AIDA team used single-cell RNA sequencing to examine immune cells. This technique allows researchers to study cells individually and compare their activity, producing a more detailed picture than treating a blood sample as a single mixture.
Across the seven population groups, the researchers found large differences in immune markers measured in blood. They also found that immune cell properties differed among ethnicities to a degree comparable with differences between men and women.
The findings connect several influences that medical research needs to consider together. A person's age and sex matter, but so does the diversity found within the Asian continent. A broad population label can leave important variation hidden.
The scale of the project gave the researchers a detailed view of that variation: more than 1.2 million cells were examined, while the people contributing those cells numbered 625. The atlas brings those observations together as a reference for further research into immune biology and health.
Age Affects Immune Cells Differently
Chinese, Malay and Indian Singaporeans provided one striking example of how age and ethnicity can interact. The study found that age affected a type of immune cell called CD4+ T naive cells differently across these three groups.
The researchers used these cells as indicators of inflammation associated with aging. Inflammation is part of the body's response to injury or illness, and changes linked to aging can help researchers investigate the risk of diseases associated with inflammation.
The different patterns suggest that those risks may also vary among the three groups. The finding points toward screening and prevention strategies that take account of the population being assessed, alongside the person's age and other characteristics.
For healthcare planning, the goal would be to identify people who need closer attention more accurately. A pattern observed in one group may provide an incomplete guide to how immune cells change with age in another.
Why a Normal Blood Test Result Can Vary
Blood tests used to investigate infectious diseases or conditions such as leukemia often measure the proportions of different white blood cells. Doctors interpret these measurements partly by comparing them with a healthy reference range, a set of values expected among people without the condition being investigated.
The AIDA study found that healthy reference ranges for immune cells can differ substantially between ethnicities and countries. A result considered normal for one group could therefore appear abnormal when judged against values drawn from another.
That creates a risk of misinterpreting a patient's results. When the comparison group does not adequately reflect the patient, a biological difference between populations may complicate the assessment of their health.
Prabhakar highlighted the need for further research to refine diagnostic criteria and improve the accuracy of medical tests across populations. Revised reference ranges and clinical guidance would require that additional work; the study sets out why it matters.
The research also identified genetic variants that influence immune cell behavior and are underrepresented in populations outside Asia. Genetic variants are differences in DNA. Finding variants relevant to immune function adds another reason to include a wider range of people in biomedical studies.
How the Atlas Could Support More Personal Care
Precision medicine aims to tailor healthcare to individual characteristics, including genetics, environment and lifestyle. AIDA contributes to that approach by showing how much immune biology can vary within a region often discussed as a single population.
Recognizing those differences could help researchers develop more accurate diagnostic tools and treatments better suited to the people receiving them. It could also help doctors interpret immune measurements with a fuller understanding of the patient's background.
The practical changes would reach beyond a laboratory result. Better assessment of disease risk could guide decisions about who needs screening, how closely someone should be monitored and where preventive care may be most useful.
The study's message is also relevant to global medical research. Including more ethnic groups would broaden the evidence used to develop tests and therapies, helping ensure that progress reaches populations that have received less attention in earlier studies.
Research Will Extend Beyond Blood
The A*Star team plans to expand its work by mapping immune cells in other parts of the body, including the skin, colon and gastric system. The researchers also aim to investigate whether different Asian ethnicities have different susceptibilities to diseases such as diabetes.
These projects would connect the atlas's findings about immune diversity with more detailed questions about disease risk. The next stage is to understand how those differences could help identify people who would benefit from earlier detection and more frequent medical attention.
Prabhakar described the connection between accurate risk assessment, clinic visits and healthcare costs:
Knowing disease risk is our best way of reducing healthcare costs, because if you know accurately who's at high risk, then you can prioritize the person and get them to come into the clinic more often. Early detection is the best way of curing and reducing healthcare costs.
The team has not given a timetable for the expansion. Its stated aim is to deepen understanding of disease susceptibility, support earlier detection and help direct healthcare resources toward people at greater risk.
Key Points
- The Asian Immune Diversity Atlas examined more than 1.2 million immune cells from 625 healthy donors across seven population groups in five Asian countries.
- The international study, led by A*Star in Singapore, was published in Cell in March 2025.
- Immune cell differences among Asian ethnicities were as pronounced as those between men and women, with age also affecting cell traits.
- Differences in healthy reference ranges could affect how blood tests are interpreted and support the case for broader representation in drug trials.
- Planned research will examine immune cells in the skin, colon and gastric system, as well as differences in susceptibility to diseases such as diabetes.
