Whole blood preservation methods alter chemokine receptor detection in mass cytometry experiments.

A potential hurdle when applying mass cytometry to the field study setting is the streamlining of sample collection while at the same time protecting the integrity of important cell epitopes. Whole blood preservation kits applying fixation and/or permeabilization agents are increasingly used in clinical trials to preserve leukocytes needed for downstream analysis. We here present a structured overview of leukocyte surface marker detectability in samples processed with four commercially available whole blood preservation kits; 1) Proteomic Stabilizer, 2) Stable-Lyse V2 and Stable-Store V2, 3) Cytodelics and 4) Lyse/Fix Buffer, as well as in samples treated with buffers included in Mass-tag Cellular Barcoding kits. Isolated leukocytes were stained with a 28-marker panel (including 7 chemokine receptors) of metal-conjugated antibodies and analysed on a mass cytometer. Exploration of the data by manual gating and viSNE analysis showed that although many markers were similarly detected across all sample conditions, most of the chemokine receptors in our panel, particularly CXCR3, CCR4, CCR6 and CXCR5, were incorrectly detected in the preserved samples and thus incompatible with the fixation and permeabilization agents found in whole blood preservation kits and in buffers used prior to barcoding.