Flow Cytometry-based Immunophenotyping for Quantifying Human Immunity and Promoting Precision Health

In the wake of the COVID-19 Pandemic, the public has become increasingly health-conscious, and many people have begun to actively go for regular check-ups to keep track of their physical well-being. As a result, the concepts of health management and precision health are gaining traction, with immunity being one of the main pillars. People would explore factors affecting immune functions in the hope of preventing diseases by boosting their immunity. Yet, most people tend to be subjective when it comes to the immunity assessment, and the related discussion remains rather vague and superficial. 

Thanks to the rapid development of diagnostic technologies, it is now possible to better understand how the human immune system functions, thereby facilitating health promotion and disease prevention. Recently, the GeneOnline team was honored to have Yen-Ling Angelo Chiu, MD, PhD, Director of the Department of Medical Research at Far Eastern Memorial Hospital (FEMH), for an interview, where he not only covered the basic principles, instrumentation and benefits of immunophenotyping, but also how this technique can contribute to the development of precision health in Taiwan.

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Analyzing Human Immune Cells for Quantifiable Immunity Indicators

Dr. Chiu began by explaining that the human immune system not only helps the body fight pathogens such as influenza and pneumonia, but also plays a key role in tissue repair as well as prevention of serious health conditions such as cancer and cardiovascular disease. The immune system contains a diverse array of immune cells with different functions and modes of operation, making it a complex and multifaceted system.

According to Dr. Chiu, the essence of immunophenotyping lies in monitoring the number, distribution and differentiation of various types of immune cells in the human body, enabling quantitative measurements for defining the level of immunity. Not only does this avoid superficial descriptions of human immunity, but it also helps people to manage their health more effectively. Given the fact that many diseases may lead to an increase in the number of abnormal immune cells, such data allow people to be aware of the balance of their immune system, and to detect abnormalities such as aging, stress, and overwork at an early stage. From a patient’s perspective, immunophenotyping can be useful for post-treatment follow-up, allowing patients and physicians to assess treatment effects by tracking changes in the immune system.

Multicolor Flow Cytometry with Dry Antibody Reagents for Improved Efficiency of Immunophenotyping

Dr. Chiu then introduced the technologies and instruments used in immunophenotyping at FEMH. He mentioned that the team primarily uses multi-color and multi-channel flow cytometry to perform immunophenotyping, allowing simultaneous detection of multiple immune cell subtypes. Moreover, only a small blood sample (approximately 300 μL, or 0.3 mL) is required from the patient to complete the procedure. The principle of this technology is to use a variety of fluorescent antibodies to identify multiple antigens expressed by individual immune cells. When the antibodies bind to specific antigens on the surface of immune cells, the fluorescent dyes attached to them can be excited by laser to produce fluorescent light of different colors (wavelengths).

The flow cytometer currently used at FEMH is CytoFlex LX provided by Beckman Coulter, a US-based life science equipment company. It supports up to 6 lasers and 21 fluorescence channels that can detect 21 colors (wavelengths) of fluorescent light simultaneously, with each type of fluorescence corresponding to a combination of antibodies and cellular markers. FEMH’s team is currently able to work with 14 colors, while not reaching the maximum performance of the device, but is capable of identifying 14 markers for each immune cell subpopulation, thus classifying the different subpopulations (T-cells, B-cells, etc.).

As for fluorescent antibodies, conventional liquid antibody reagents may encounter issues such as complex preparation procedures, difficulties in storage, and decay of fluorescence intensity under the influence of storage time and temperature. Dr. Chiu mentioned that with the help of Beckman’s dry-type antibody reagents, they are not only able to customize the antibodies used, but also improve the resolution and stability of the immunophenotyping process, rendering a more convenient and efficient workflow.

Establishment of a Large-scale Database of Healthy Individuals to Enhance Testing Accuracy

According to Dr. Chiu, FEMH’s immunophenotyping can cover various subpopulations of immune cells, such as T cells, B cells, natural killer cells, monocytes, and dendritic cells, providing a quantitative assessment of an individual’s immune system. Currently, the team has established a database comprising hundreds of healthy individuals across different age groups, which is by far the largest in Taiwan. By collecting and organizing the immune cell data of a large number of people with normal health conditions, an objective range of normal values can be established for reference by healthcare professionals. If a patient’s test data deviates from this range, physicians can deduce that their immune system may be abnormal and take follow-up actions accordingly.

He also pointed out that immunophenotyping can be of great help to physicians in monitoring the efficacy of treatment. For example, they can track how well a cancer patient’s cells regenerate after chemotherapy to fine-tune the treatment course. For autoimmune diseases, physicians can use the test results to confirm whether B cell depletion therapy has actually achieved its goal of eliminating B cells, or to accurately calculate the amount of immunosuppressants needed to adequately suppress the immune system. Furthermore, in case a patient needs to undergo any cell therapy, physicians can refer to the data obtained from immunophenotyping to identify the subtype of immune cells that the patient is deficient in, and then select the appropriate type of cell therapy to suit the patient’s needs.

Combining Prevention and Treatment for Precision Health

In recent years, the concept of precision health has emerged to encompass not only personalized, targeted treatment and care strategies, but also accurate disease screening, prediction and prevention to prevent diseases from occurring in the first place. FEMH is also following the trend of preventive medicine by applying immunophenotyping to both therapeutic and preventive medicine. 

In FEMH’s Health Management Center, for example, Dr. Chiu said that since he joined FEMH eight years ago, the center has begun to explore the issue of “suboptimal health status”. He noted that clinicians used to focus on managing diseases, but did not pay much attention to the aging process and lacked precise descriptions of changes in the immune system. 

With people becoming more concerned about their health as they live longer, coupled with rapid advances in testing technologies, physicians and patients are gaining a better understanding of the immune system and how the human body may change from a healthy to an aged or diseased state. He suggested that the establishment of a database of healthy individuals has made a significant contribution in this regard. For instance, in case of neurodegenerative disorders, it would be difficult to identify the true cause of dementia and the process of brain degeneration if studies focus only on dementia patients with degenerated brains without data on healthy individuals for comparative purposes.

Beyond aging-related diseases, Dr. Chiu also emphasized that immunophenotyping can be an important tool for health management. Apart from providing people with a more accurate picture of their current health condition, these diagnostic tests would help people to stop being complacent with the normal-looking results of a single health check, but instead they can recognize any trends of variation and intervene promptly in case their conditions are deteriorating (e.g., elevating blood glucose levels, loss of muscle mass, and intestinal polyps, etc.), ensuring prompt intervention to treat the disease at its earliest stages.

Overall, the interview not only presented the working principles, versatile applications and clinical advantages of immunophenotyping, but also FEMH’s achievements in research and application in this field. Following the advancements in relevant equipment and technologies, it is expected that immunophenotyping will continue to promote the development of medical testing and personalized treatment, contributing to the establishment of a precision health system in Taiwan that emphasizes both prevention and treatment.

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Author

Richard Chau