Absolute T Cell Counts by Flow Cytometry

Flow cytometry of absolute counts for T cells were analyzed in Trucount tubes (BD, Franklin Lakes, NJ, USA) on a FacsCanto II instrument and analyzed in BD FACSCanto™ Clinical Software according to the instructions provided by the manufacturer (BD). Instrument settings were standardized as recommended by the manufacturer with daily quality run with CS&T Beads (BD) and 7-color Setup Beads (BD) ensuring high reproducibility. The laboratory follows standard operation procedure and also has ISO (International Standard Organization) certification. Further sub-classification of T cells was performed on a Gallios Flow cytometer (Beckman Coulter, San Diego, CA, USA) as previously described (9 (link)). Reference values (5–95 percentile) for absolute numbers of T and NK-cells, and T-subpopulations were established on samples from healthy blood donors (n = 65).