APTT reagent with ellagic acid as activator shows adequate lupus anticoagulant sensitivity in comparison to silica-based reagent.
BACKGROUND
Lupus anticoagulant (LA) is an antibody that interferes with phospholipid-dependent coagulation reactions. Activated partial thromboplastin time (APTT) is widely used as a test for LA screening. APTT reagents are composed of activators, such as silica or ellagic acid, and phospholipids, and APTT reagents with silica are recommended for LA screening because of greater sensitivity. However, the effects of activators on LA activity have not been adequately investigated.


OBJECTIVE
In this study, we examined whether an ellagic acid-based reagent was highly sensitive to LA in a low phospholipid condition and useful for LA screening.


METHODS
Silica-based (SL) and ellagic acid-based (EA) reagents were prepared in-house with the same composition and concentration of phospholipids, while the commercial APTT reagents APTT-SLA (SLA), Actin FSL (FSL), APTT-SP (SP) and PTT-LA (PTT) were also included in the study.


RESULTS
The normal reference ranges for SL and EA were 30.1-47.0 and 28.0-40.2 s, respectively, while the cut-off index values for circulating anticoagulant activity (ICA) calculated from the results obtained with SL, EA, SLA, FSL, SP and PTT were 12.9, 11.5, 13.2, 15.6, 14.3 and 14.0, respectively. The sensitivity of those reagents based on those cut-off values was 91%, 96%, 68%, 46%, 91% and 86%, respectively.


CONCLUSIONS
Our results showed that the ellagic acid-based reagent was more sensitive to LA than silica-based reagents in a low phospholipid condition and had adequate sensitivity to detect LA. We concluded that the sensitivity of APTT reagents for LA is dependent on phospholipid concentration and not the activator.
Department of Internal Medicine Clinical Laboratory, School of Dentistry, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido, Japan.
O
O
Kumano
M
M
Ieko
S
S
Naito
M
M
Yoshida
N
N
Takahashi
D000465:Algorithms; D001777:Blood Coagulation; D004610:Ellagic Acid / Q000737:chemistry*; D006801:Humans; D007202:Indicators and Reagents; D016682:Lupus Coagulation Inhibitor / Q000737:chemistry*; D010314:Partial Thromboplastin Time / Q000379:methods*; D010743:Phospholipids / Q000737:chemistry; D012016:Reference Values; D012680:Sensitivity and Specificity; D012822:Silicon Dioxide / Q000737:chemistry*
D007202:Indicators and Reagents; D016682:Lupus Coagulation Inhibitor; D010743:Phospholipids; D004610:Ellagic Acid; D012822:Silicon Dioxide