Centrifugal Speed Affects Light Transmission Aggregometry

Light transmission aggregometry (LTA) is considered the gold standard for investigating platelet activity ex vivo, but LTA protocols are not standardized.

Centrifugation speed is an essential component of platelet preparation in LTA and has yet to be standardized, which may affect platelet aggregation leading to a potential source of variance in results.

In a study, conducted at the New York University School of Medicine (NY, USA) the effect of relative centrifugal force (RCF) intensity on LTA results was investigated. Ten healthy controls had venous blood drawn and centrifuged at 150, 200, 300, and 500 × g for 10 minutes. Cell counts in whole blood and platelet-rich plasma (PRP) were measured using a hematology analyzer. LTA was performed using 1.0 µM adenosine diphosphate (ADP) and 0.4 µM epinephrine as an agonist. The percentage of aggregation was compared at 60, 120, 180, and 300 seconds and at maximum aggregation.

Centrifugation speed was associated with a statistically significant decrease in platelet counts and decrease in mean platelet volume in PRP. Consistently, platelet aggregation in response to 0.4 µM of epinephrine decreased significantly with increasing centrifuge RCF at 60, 120, 180, 300 seconds and at maximum aggregation. Whole blood and PRP cell blood count were performed using a Sysmex XE-2100 analyzer (Mundelein, IL, USA). LTA was performed using the AggRAM light transmission aggregometer, reagents, cuvettes, and stir bars (Helena Laboratories, Beaumont, TX, USA).

The authors concluded that using different centrifuge RCF results in changes in PRP properties and LTA. This difference in methodology gives pause to comparing LTA from studies with different protocols and may help explain some of the inconsistencies observed in the field. Consequently, consideration should be given to standardize centrifugation parameters in performing LTA. The study is planned to appear in the February 2012 print edition of the International Journal of Laboratory Hematology.

Related Links:
New York University School of Medicine
Sysmex
Helena Laboratories