Standard PBMC cryopreservation selectively decreases detection of nine clinically-relevant T-cell markers

Although peripheral blood is routinely acquired and stored in biobanks, the effects of specimen processing on cell composition and clinically-relevant functional markers of T cells still require a systematic evaluation. Here we assessed 25 relevant T-cell markers in human peripheral blood mononuclear cells (PBMCs) and showed that the detection of nine membrane markers, e.g., PD-1, CTLA4, KLRG1, CD25, CD122, CD127, CCR7 and others reflecting exhaustion, senescence and other functions was reduced among at least one T-cell subset following standard processing, although the frequency of CD4, CD8 and regulatory T cells was unaffected.

Nevertheless, a six-month-long cryopreservation did not impair the percentages of cells expressing many other membrane and all the eight tested intracellular lineage or functional T-cell markers. Our findings uncover that several clinically-relevant markers are particularly affected by processing and the interpretation of those results in clinical trials and translational research should be done with caution.