Evaluation of Coagtrol N for Use as Normal Plasma in Mixing Tests

• Evaluation of Coagtrol N for Use as Normal Plasma in Mixing Tests

AUTHOR(S)

Daiki SHIMOMURA*^１, Kaori UEDA*^２, Shinichi KATO*^２ and Fumihiko NAKAMURA*^１

*1 Department of Laboratory Medicine, Tenri Hospital
*2 Sysmex Corporation

SUMMARY

Background: The selection of normal plasma is an important factor in mixing tests used for the detection of lupus anticoagulant (LA), since residual platelets (phospholipids) can shorten clotting time and, affect mixing test results. Here, we investigated whether Coagtrol N (CoagN), a type of commercially available lyophilized plasma in Japan, can be used as normal plasma in mixing tests for widening the use of cross mixing tests.

Methods: Three lots of CoagN were evaluated using plasma samples from 23 LA-positive patients. CRYOCheck Pooled Normal Plasma (PBI) and homemade pooled normal plasma (HM) were used as controls. Mixing tests were performed with six mixing ratios (1:0, 4:1, 1:1, 1:4, 1:9, 0:1) of patient to normal plasma. The activated partial thromboplastin time (APTT) of the mixing test samples was measured, and the index of circulating anticoagulant (ICA) and the 4:1 mix percent correction (4:1%Co) were compared.

Results: The platelet count for all normal plasma, obtained using a platelet specific monoclonal mouse anti-human CD41 was < 10×109/L. The median ICA for patient plasma (n = 23) was 28.8, 27.9, 31.9, 23.8, 33.2 for CoagN (Lot.021), CoagN (Lot.022), CoagN (Lot.023), HM and PBI, respectively. All the CoagN lots had significantly higher ICA than HM and CoagN (Lot.022) alone had significantly lower ICA than PBI (p < 0.001). The proportions of patient plasmas assessed as inhibitor positive because of ICA ≥12 were respectively 100% CoagN (Lot.021), 96% CoagN (Lot.022), 100% CoagN (Lot.023), 96% HM and 100% PBI. The median 4:1%Co in patient plasma (n = 23) was 9.5, 12.5, 8.6, 12.2, 9.9 for CoagN (Lot.021), CoagN (Lot.022), CoagN (Lot.023), HM and PBI, respectively. All of the patient samples were inhibitor-positive with a 4:1%Co < 50 using normal plasma.

Conclusion: CoagN had no significant impact on the detection of inhibitors compared to PBI and HM; therefore, we conclude that CoagN can be used as a substitute for normal plasma in mixing tests. It indicates that the findings of this study will contribute to the widespread use of mixing tests.

KEY WORDS

APTT, Coagtrol N, ICA, 4:1%Co, Mixing Test, Normal Plasma

NOTE(S)

This article is translated and republished from the Sysmex Journal Web Vol.18 No.1, 2017. (Japanese)