Multicentre evaluation of stable reference whole blood for enumeration of lymphocyte subsets by flow cytometry.
BACKGROUND: Clinical indications for lymphocyte subset enumeration by flow cytometry include monitoring of disease progression and timing of therapeutic intervention in infection with human immunodeficiency virus. Until recently international standardisation has not been possible due to a lack of suitable stable reference material. METHODS: This study consisted of two trials of a stabilised whole blood preparation. Eleven participants were sent two standard protocols for staining plus gating strategy and asked to report absolute counts for lymphocyte subsets. RESULTS: No significant difference was detected between the two methods when results from the two assays and all partners were pooled. Significant differences in results from the different partners were observed. However, representative mean counts were obtained for geometric means, geometric coefficient of variation, and 95% confidence interval for CD3 910 cells/mul, 9%, and 888 to 933, respectively), CD4 (495 cells/mul, 12%, and 483 to 507), and CD8 (408 cells/mul, 13%, and 393 to 422). CONCLUSION: We have introduced a stabilised blood preparation and a well-characterized biological standard. The availability of this reference material greatly simplifies the validation of new techniques for CD4(+) T-cell enumeration and the expansion of external quality assurance programmes for clinical laboratories, including those that operate in resource-restricted environments. (c) 2005 Wiley-Liss, Inc.
Edwards
Cherry
C
National Institute for Biological Standards and Control, Potters Bar, United Kingdom.
Belgrave
Danielle
D
Janossy
George
G
Bradley
Nicholas J
NJ
Stebbings
Richard
R
Gaines-Das
Rose
R
Thorpe
Robin
R
Sawle
Alex
A
Arroz
Maria Jorge
MJ
Brando
Bruno
B
Gratama
Jan Willem
JW
Orfao de Matos
Alberto
A
Papa
Stephano
S
Papamichail
Michael
M
Lenkei
Rodica
R
Rothe
Gregor
G
Barnett
David
D