Scientists developed a dye-free method to analyze immune cells in blood samples, achieving 94% accuracy in identifying activated cells within two hours using optical metabolic imaging, according to research published in Biophotonics Discovery.
Researchers have unveiled a technique to study immune cells without chemical dyes, offering a view of the body’s defense system. The method, described in a study published in Biophotonics Discovery, uses natural fluorescence from cells to assess their metabolic state, distinguishing activated immune cells from resting ones with nearly 94% accuracy. This advancement could transform diagnostic tools and cell therapy development.
A New Way to Study Immune Cells
The technique, known as optical metabolic imaging (OMI), relies on two-photon microscopy to measure the natural fluorescence of molecules involved in cellular metabolism. Unlike traditional methods that require fluorescent dyes or antibodies, OMI captures the autofluorescence lifetime of cells—how long molecules remain in an excited state before returning to their normal state. This provides insights into a cell’s functional activity without altering its structure.
Scientists analysed thousands of immune cells from ordinary blood
In experiments, scientists analyzed thousands of peripheral blood mononuclear cells (PBMCs) from three healthy donors. Machine-learning algorithms processed the metabolic data to identify immune-cell types and detect activation. The method achieved 94% accuracy in distinguishing activated PBMCs from resting ones just two hours after stimulation, a critical window for immune responses. Monocytes, key players in the innate immune system, were identified with 96% accuracy at rest and 88% after activation, while natural killer (NK) cells showed 74% accuracy in both states.
PBMCs can be isolated clinically really easily, and they’re already used in the clinical workflow,
said Dr. Melissa Skala, senior author of the study and leader of the Skala Lab at the Morgridge Institute for Research. So, the question is, what can we get from them that we aren’t already getting?
The answer, according to the research, is a deeper understanding of cellular metabolism, which could reveal how immune cells respond to threats or disease.
Implications for Medical Diagnostics
The study highlights how immune-cell metabolism provides information beyond traditional markers. While surface proteins can identify cell types, metabolic profiles reveal functional states—whether cells are active, quiescent, or responding to stimuli. This could be particularly valuable in conditions like cancer, autoimmune disorders, and infections, where immune activity is a key indicator.
Single-cell analysis also exposed previously hidden variability. For example, some monocytes showed high metabolic activity while others remained quiet, a distinction that bulk measurements would average out. By measuring metabolism at the level of individual cells, OMI offers a detailed picture of how the immune system functions.
Optical imaging can reveal the metabolic activity of individual
The non-destructive nature of OMI makes it promising for cell therapy applications. PBMCs are already used in treatments like CAR T-cell therapy, and the technique could help assess the quality or fitness of cells before further processing. This could eventually help researchers evaluate cells for therapeutic use.
What’s Next for the Research?
While the study focused on healthy donors, future work will explore how the method performs in disease models. Researchers aim to validate its effectiveness in clinical settings, particularly for conditions where immune dysregulation plays a role. The technique’s speed—processing samples in two hours—also raises questions about its potential for real-time diagnostics.
However, challenges remain. Adaptive immune cells like T and B cells showed more similar metabolic profiles under the experimental conditions, suggesting the method may need refinement for broader applications. Additionally, the research did not address how metabolic changes correlate with specific diseases, a gap that future studies will need to fill.
As the field advances, the ability to study immune cells without chemical labels could reduce costs and simplify workflows. For now, the study marks a step toward more nuanced immune system analysis, with potential impacts on both basic research and patient care.
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Dr. Skala, who is also the Carol Skornicka Chair
at the Morgridge Institute for Research and a professor of biomedical engineering and medical physics at the University of Wisconsin–Madison, emphasized the clinical relevance of PBMCs. These cells are routinely studied in conditions ranging from blood cancers and sepsis to lupus and cognitive decline. They also serve as the starting material for cell therapies such as chimeric antigen receptor T-cell (CAR T) treatments, which can engineer a patient’s own immune cells to attack cancer.
The study’s findings underscore the potential of optical metabolic imaging to complement existing methods. While fluorescent labels provide specific surface marker data, OMI offers insights into cellular function. This dual approach could enhance diagnostic precision and therapeutic monitoring, according to the research team.
Experts in the field have noted the significance of the study’s non-destructive methodology. The method’s compatibility with existing clinical workflows further strengthens its appeal for translational research.
The research was conducted at the Skala Lab, which is part of the Morgridge Institute for Research. The institution, based in Madison, USA, is known for its interdisciplinary approach to biomedical innovation. The study was published in the journal Biophotonics Discovery.
As the field of immunology continues to evolve, techniques like OMI represent a step toward personalized medicine. By decoding the metabolic signatures of individual immune cells, researchers are paving the way for more targeted interventions and a deeper understanding of the body’s defense mechanisms.
