A new one-platform flow cytometric method for residual cell counting in platelet concentrates.
BACKGROUND
According to German regulations and guidelines, residual red blood cells (rRBCs) and residual white blood cells (rWBCs) must number fewer than 3 x 10(9) cells/unit and 1 x 10(6) cells/unit in platelet concentrates (PCs), respectively. Due to low levels of residual cells in final products, there is still a need for fast, reliable, and sensitive methods of automated detection of these cell types.


METHODS
In Part A, 21 PCs were spiked with predetermined numbers of red blood cells (RBCs) and white blood cells (WBCs). The linearity, precision, and accuracy of the BD Thrombo Count assay (BD Biosciences Europe) were tested and validated according to international guidelines. Finally in Part B, 100 PCs prepared from pooled buffy coats were tested by the BD Thrombo Count assay and compared with other methods, including Nageotte (rWBCs) and Neubauer (rRBCs) counting chambers and the flow cytometric BD LeucoCOUNT (Becton Dickinson) assay (rWBCs).


RESULTS
The unspecific background of blank PC samples was fewer than 0.02 cells/microL for WBCs and fewer than 34 cells/microL for RBCs (mean, 21). Linear regression and precision analyses of spiked PC samples were determined for both WBCs (r(2) = 0.992; range, 0.6-6.0 WBCs/microL) and RBCs (r(2) = 0.999; 800-8000 RBCs/microL). No carryover of cells or drift in results was detected in the automated sample acquisition mode. Analysis according to statistical methods of Bland and Altman demonstrated a high correlation between BD Thrombo Count and the Neubauer manual counting chamber.


CONCLUSIONS
This novel flow cytometric test is a quick and reliable single-tube assay that has been demonstrated as a potential alternative for the existing manual microscopic counting procedures that are both time-consuming and laborious.
Schmidt
Michael
M
Institute of Transfusion Medicine and Immunohematology, German Red Cross, Johann Wolfgang Goethe University, Frankfurt, Germany.
Spengler
Hans-Peter
HP
Lambrecht
Bernd
B
Hourfar
Michael K
MK
Seifried
Erhard
E
Tonn
Torsten
T
D004906:Erythrocyte Count / Q000379:methods* / Q000592:standards; D004912:Erythrocytes / Q000166:cytology; D005434:Flow Cytometry / Q000379:methods* / Q000592:standards; D006801:Humans; D007958:Leukocyte Count / Q000379:methods* / Q000592:standards; D007962:Leukocytes / Q000166:cytology; D010976:Platelet Count; D010983:Plateletpheresis / Q000592:standards*; D011786:Quality Control; D015203:Reproducibility of Results