[Counting platelets by flow cytometry with platelet-specific antibody CD42a].
OBJECTIVE
To investigate a reference method for platelet (PLT) count.


METHODS
76 samples of daily whole blood of high, normal and low values in patients were collected and analyzed by flow cytometry (FCM) with CD42a monoclonal antibody that could combine specifically with the platelet membrane glycoprotein Ib-Ix (GPIb-Ix). PLT counts were analyzed by multiplying PLT/RBC ratio from FCM with the RBC that was counted by a calibrated blood analyzer. Meanwhile, the results of PLT from FCM were compared with that from blood analyzers SE-9500, NE-1500, CD-1600 or manual count.


RESULTS
The within-replicate coefficient of variance(CV) of FCM was less than 4% for a high count(501 x 10(9)/L) and middle count(184 x 10(9)/L), the CV of low count(23 x 10(9)/L) was 11.432%, the between-replicate CV was 10.792%, and the overall reproducibility was less than 5%. Linearity was demonstrated well(r = 0.9975 P < 0.001) when the PLT counts were 20 x 10(9)/L-700 x 10(9)/L. PLT count was stable at room temperature within 6 hr. The carry-over was 0.87%. The results between FCM and SE-9500, NE-1500, CD-1600 or manual count was comparable (r > 0.975, P < 0.001).


CONCLUSIONS
These findings confirm that FCM for PLT count is specific, accurate and precise and could be considered as a candidate of reference method for PLT count.
Peng
L
L
Department of Laboratory Medicine, First Affiliated Hospital, WCUMS, Chengdu 610041, China.
Jiang
H
H
Yang
H
H
Zhu
X
X
D000911:Antibodies, Monoclonal / Q000032:analysis / Q000276:immunology; D005434:Flow Cytometry; D006801:Humans; D010976:Platelet Count / Q000379:methods; D019038:Platelet Glycoprotein GPIb-IX Complex / Q000276:immunology*
D000911:Antibodies, Monoclonal; D019038:Platelet Glycoprotein GPIb-IX Complex