Preservation of antithrombin III activity in stored whole blood

Effects of frozen storage conditions and freezing rate on the stability of coagulation proteins in human plasma

OBJECTIVES

Degradation of coagulation proteins in frozen plasma may influence assay results. The aims of this study were to explore the changes in coagulation parameters in patient plasma and internal quality control (IQC) after different freezing and storage conditions during the short-term and long-term periods.

METHODS

Platelet poor plasma was prepared from citrated peripheral blood collected from a group of healthy donors. The plasma was pooled, frozen and stored in a variety of freezing and storage conditions. The changes were monitored using routine coagulation assays, as well as factor VIII (FVIII) and protein S (PS) assays.

RESULTS

Plasma stored in liquid nitrogen (LN 2 ) or in -80°C showed long-term stable values for routine tests for a period of over 12 months, and 6 months for FVIII. Interestingly, the activated partial thromboplastin time (aPTT) showed a temporary significant prolongation over the first two weeks. Plasma frozen and stored in -40°C is not viable for aPTT and FVIII testing, otherwise it can be used for other parameters for up to 4 months. PS showed a significant increase in all frozen samples. Freezing rate has a significant impact on plasma quality and the final storage temperature influences the long-term stability.

CONCLUSION

The optimal storage conditions are ultra-low temperatures (LN 2 or -80°C) and the highest freezing rate possible. However, frozen plasma is not viable for IQC of aPTT during a period of two weeks after freezing. This study is unique in its conception as a practical guide for the handling of frozen plasma samples in modern laboratory settings.

Label-Free Method Development for Hydroxyproline PTM Mapping in Human Plasma Proteome

Post-translational modifications (PTMs) impart structural heterogeneities that can alter plasma proteins' functions in various pathophysiological processes. However, the identification and mapping of PTMs in untargeted plasma proteomics is still a challenge due to the presence of diverse components in blood. Here, we report a label-free method for identifying and mapping hydroxylated proteins using tandem mass spectrometry (MS/MS) in the human plasma sample. Our untargeted proteomics approach led us to identify 676 de novo sequenced peptides in human plasma that correspond to 201 proteins, out of which 11 plasma proteins were found to be hydroxylated. Among these hydroxylated proteins, Immunoglobulin A1 (IgA1) heavy chain was found to be modified at residue 285 (Pro²⁸⁵ to Hyp²⁸⁵), which was further validated by MS/MS study. Molecular dynamics (MD) simulation analysis demonstrated that this proline hydroxylation in IgA1 caused both local and global structural changes. Overall, this study provides a comprehensive understanding of the protein profile containing Hyp PTMs in human plasma and shows the future perspective of identifying and discriminating Hyp PTM in the normal and the diseased proteomes.

The quality of fresh-frozen plasma produced from whole blood stored at 4°C overnight

BACKGROUND

The aim of this study was to assess whether the quality of FFP produced from whole blood stored at 4 degrees C overnight is adequate for its intended purpose.

STUDY DESIGN AND METHODS

Fresh-frozen plasma (FFP) separated from whole blood (n = 60) leukodepleted (LD) after storage at 4 degrees C overnight (18-24 hr from donation, Day 1 FFP) was compared with that LD within 8 hours of donation (Day 0 FFP, the current standard method).

RESULTS

In more than 95 percent of Day 1 FFP units, levels of factor (F) II, FV, FVII, FVIII, F IX, FX, FXI, and FXII were greater than 0.50 U per mL except for von Willebrand factor (VWF) antigen and FVIII, where 92 and 87 percent of units, respectively, contained greater than 0.50 IU per mL. Compared with historical data on FFP stored for 8 hours, fibrinogen, FV, FVIII, and FXI were reduced by 12, 15, 23, and 7 percent, respectively, but other factors were not significantly reduced. Levels of VWF-cleaving protease activity were not different between FFP prepared from paired units of blood (n = 3) held for 8 or 24 hours, but were below the reference range in an additional 2 of 6 units held for 24 hours. The activities of protein S, protein C, antithrombin III, and alpha(2)-antiplasmin were reduced by less than 10 percent in Day 1 FFP (n = 20), but with final levels above the lower limit of the normal range in greater than 95 percent of units. Activated FXII antigen was not significantly raised in plasma stored for 18 to 24 hours, but levels of prothrombin fragment 1 + 2 were slightly increased (0.88 ng/mL, 18-24 hr; 0.65 ng/mL, < 8 hr).

CONCLUSION

These data suggest that there is good retention of relevant coagulation factor activity in plasma produced from whole blood stored at 4 degrees C for 18 to 24 hours and that this would be an acceptable product for most patients requiring FFP.

Effect of 24-hour whole-blood storage on plasma clotting factors

BACKGROUND

The current requirements for the preparation of fresh-frozen plasma within 8 hours of whole-blood collection were designed to maintain clotting factor activities. These requirements, however, limit the production of fresh-frozen plasma in a large blood center. There are few data on the effect of the extension of CPD whole-blood storage to 24 hours on clotting factor activity.

STUDY DESIGN AND METHODS

A 500-mL unit of whole blood was collected from 10 volunteer donors. At 1 hour after collection, a plasma sample was separated by centrifugation, and each unit was equally divided into 2 half-units, with 1 half-unit stored at 4 degrees C (range, 1-6 degrees C) and 1 half-unit stored at 22 degrees C (range, 20-24 degrees C) for 8 hours after collection. Each half-unit was then placed at 4 degrees C for further storage for 16 hours. At 8 and 24 hours after collection, plasma samples were separated from each half-unit. All plasma samples were frozen at -18 degrees C. Factors V, VII, VIII, and X; fibrinogen; antithrombin III; protein C; and protein S were measured.

RESULTS

No significant changes were noted in factors V, VII, and X; fibrinogen; antithrombin III; protein C; and protein S over the 24-hour storage period. Factor VIII in both half-units was significantly reduced, by 13 percent, from the baseline sample as compared to the level in the 8-hour storage sample (p<0.05). Factor VIII was further reduced by 15 to 20 percent after the 24-hour storage period (p<0.05).

CONCLUSION

The coagulation factor activity for all factors measured, with the exception of factor VIII, showed no significant change over the 24-hour storage period. Factor VIII was significantly decreased by 13 percent in 8-hour storage and by an additional 15 to 20 percent in 24-hour storage. For clinical situations not requiring the replacement of factor VIII only, 24-hour frozen plasma has properties comparable to those of fresh-frozen plasma.

Pathophysiology of antithrombin III deficiency

This article focuses on the pathophysiology of thrombosis in patients with acquired antithrombin III deficiency. Antithrombin III is an important natural inhibitor of the hemostatic mechanism, and a hypercoagulable state is often induced in diseases causing antithrombin III deficiency. Laboratory determination of antithrombin III activity is particularly useful in the clinical evaluation and therapeutic management of patients with disseminated intravascular coagulation, nephrotic syndrome, and severe hepatopathy.

Antithrombin III (ATIII) Activity in Plasmas from Normal and Diseased Horses, and in Normal Canine, Bovine and Human Plasmas

Plasma Antithrombin III (ATIII) activity was quantitated in 24 clinically normal Standardbred/Thoroughbred horses using a clotting time technique. ATIII activity ranged from 80 to 106% of the pooled reference standard plasma, with a mean of 94%. Horses presenting with impaction or spasmotic colic (n=17) had normal plasma ATIII activity, while 15 horses presenting with acute diarrhea/colitis had significantly lower plasma ATIII activity with a mean of only 74% of the reference plasma. Seven horses presenting with liver disease had significantly higher plasma ATIII activity with a range of 127 to 177% of the pooled reference plasma. Fifty-seven equine plasmas were retested using a rapid chromogenic substrate technique for quantitating plasma ATIII activity. A good correlation (r =+0.83) existed between clotting time and chromogenic determinations of ATIII. Pooled normal canine, human and bovine plasmas had only 65, 62 and 79%, respectively, of the ATIII activity of the equine reference plasma.