This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: A routine blood sample contains a diverse collection of immune cells that can reveal important clues about health and disease. These cells, known as peripheral blood mononuclear cells (PBMCs), are widely used to study infections, autoimmune disorders, cancer and the immune system's response to treatment.
Scientists typically identify these cells using fluorescent labels that attach to specific surface markers. While effective, those methods provide limited information about how the cells are functioning and can alter the cells during preparation. As reported in Biophotonics Discovery, a recent study shows how advanced optical imaging can reveal a previously inaccessible layer of information: the metabolic activity of individual immune cells within a complex blood sample.
"PBMCs can be isolated clinically really easily, and they're already used in the clinical workflow," says Melissa Skala of the Morgridge Institute for Research and the University of Wisconsin–Madison, senior author of the study. "So, the question is, what can we get from them that we aren't already getting?" That question has growing clinical relevance. PBMCs 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 CAR T-cell treatments, which engineer a patient's own immune cells to attack cancer. Understanding not just how many immune cells are present, but how active and metabolically fit they are, could provide new insights into disease progression and treatment response. Traditionally, measuring immune-cell metabolism requires either isolating specific cell populations or adding fluorescent labels and chemical probes.
These approaches can alter cells, consume samples or fail to capture how different cell types behave together. In contrast, the new study demonstrates a nondestructive method that measures metabolism in individual immune cells while they remain part of a heterogeneous PBMC sample. To accomplish this, the researchers used optical metabolic imaging (OMI), a technique developed and refined by the Skala Lab.
OMI relies on the natural fluorescence of molecules involved in cellular energy production. Rather than introducing external dyes, the method uses two-photon microscopy to excite naturally occurring metabolic cofactors inside cells and measure how long they emit light. These fluorescence lifetimes provide information about cellular metabolism and activation state.
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