An interlaboratory study of a candidate reference method for platelet counting.
A multinational interlaboratory task force explored the important variables of platelet reference counting and developed a candidate flow cytometric reference method based on the RBC/platelet ratio. A multicenter comparison was performed to determine whether the method met the necessary criteria and was precise enough to be recommended as a new reference method. Each laboratory analyzed serial dilutions of normal specimens, stabilized material, and at least 60 patient specimens with a range of platelet counts from 1 to 400 x 10(3)/microL (1-400 x 10(9)/L). Pooled analysis of the serial dilutions showed that RBC-platelet and RBC-RBC coincidence events became negligible at sufficiently high dilutions (i.e., > 1:1,000). All laboratories demonstrated excellent intra-assay and acceptable interlaboratory precision. Two antibodies (CD61 and CD41) were used for identifying platelets and individually gave acceptable results, but in a minority of samples, staining differences were observed. The optimum method thus uses a double-labeling procedure with a final dilution factor of 1:1,000. The study demonstrated that this method meets the criteria for a reference platelet count.
University College London, London, England.
P
P
Harrison
K A
KA
Ault
S
S
Chapman
L
L
Charie
B
B
Davis
K
K
Fujimoto
B
B
Houwen
J
J
Kunicka
F
F
Lacombe
S
S
Machin
R
R
Raynor
L
L
van Hove
O W
OW
van Assendelft
D000925:Anticoagulants; D015703:Antigens, CD / Q000097:blood; D001792:Blood Platelets / Q000276:immunology; D001800:Blood Specimen Collection / Q000379:methods; D004492:Edetic Acid; D004906:Erythrocyte Count; D005434:Flow Cytometry / Q000295:instrumentation; D006801:Humans; D039661:Integrin beta3; D007753:Laboratories; D010976:Platelet Count / Q000379:methods / Q000592:standards*; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000032:analysis; D010980:Platelet Membrane Glycoproteins; D011786:Quality Control; D012015:Reference Standards; D012680:Sensitivity and Specificity
D000925:Anticoagulants; D015703:Antigens, CD; D039661:Integrin beta3; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D010980:Platelet Membrane Glycoproteins; D004492:Edetic Acid