Effect of time, temperature and additives on a functional assay of C1 inhibitor.
Author(s): Nielsen EW, Johansen HT, Straume B, Mollnes TE
Publication: J Immunol Methods, 1994, Vol. 173, Page 245-51
PubMed ID: 8046257 PubMed Review Paper? No
Purpose of Paper
Conclusion of Paper
Studies
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Study Purpose
The purpose of this study was to determine the effects of anticoagulant and storage at 4 or 37 degrees C for up to 24 h on the activity of C1-INH in plasma and serum from normal and HAE patients. Serum specimens were allowed to coagulate for 2 h at room temperature prior to centrifugation. After the allotted storage time, all specimens were stored at -70 degrees C until analysis.
Summary of Findings:
C1-INH activity was falsely elevated in heparin treated plasma and falsely depressed in polybrene-EDTA treated plasma. Significantly higher C1-INH activity was observed in serum, EDTA-treated plasma and heparin-treated plasma, then in citrate-treated plasma from healthy volunteers (p=0.0003-0.0025), but not from HAE patients (p=0.055-0.8). Activity of C1-INH decreased by 12-19% after storage of normal plasma (EDTA, heparin, or citrate-treated) or serum for 24 h at 37 degrees C. A decline in C1-INH activity of 5-14% was noted after 24 h at 4 degrees C for normal plasma (EDTA, heparin, or citrate-treated) or serum. The decline in C1-INH activity was far more pronounced in HAE patients after storage at either 37 (48-83%) or 4 degrees C (35-80%) and was also found for polybrene-EDTA-treated plasma. Although a significant effect of storage was found for both healthy volunteers (p=0.039) and HAE patients (0.0002) there was no significant difference between the two temperatures. In conclusion, EDTA-treated plasma or serum were the best choices for measurement of C1-INH activity and C1-INH activity declines with storage at 4 or 37 degrees C.
Biospecimens
Preservative Types
- Frozen
Diagnoses:
- Normal
- Other diagnoses
Platform:
Analyte Technology Platform Protein Enzyme assay Pre-analytical Factors:
Classification Pre-analytical Factor Value(s) Preaquisition Diagnosis/ patient condition Hereditary angioedema
Storage Storage temperature -70 degrees C
4 degrees C
37 degrees C
Storage Storage conditions 0 h
6 h
24 h
Biospecimen Acquisition Anticoagulant EDTA
Heparin
Sodium citrate
Polybrene EDTA
Biospecimen Aliquots and Components Blood and blood products Plasma
Serum
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Study Purpose
The purpose of this study was to determine the effect of storage of serum at room temperature for up to 5 days on the activity and protein levels of C1-INH from healthy volunteers and HAE patients. After the allotted storage time, all specimens were stored at -70 degrees C until analysis.
Summary of Findings:
Storage of pooled serum at room temperature decreased C1-INH activity levels by 15% after 1 day, 20% after 2 days, 24% after 3 days, and 22% after 5 days (p=0.055). While no changes in C1-INH levels in healthy individuals were observed by Western blot after 5 days of storage at room temperature, in HAE patients, the band representing intact C1-INH disappeared and a faint smaller band appeared after 5 days at room temperature. In addition, a new higher molecular weight band appeared both in serum from healthy volunteers and HAE patients. In conclusion, storage of serum at room temperature reduces C1-INH activity, but an observable effect on C1-INH levels by Western blot was only found in HAE patients.
Biospecimens
Preservative Types
- Frozen
Diagnoses:
- Normal
- Other diagnoses
Platform:
Analyte Technology Platform Protein Enzyme assay Protein Western blot Pre-analytical Factors:
Classification Pre-analytical Factor Value(s) Storage Time at room temperature 0 days
1 day
2 days
3 days
5 days
Storage Storage temperature -70 degrees C
Preaquisition Diagnosis/ patient condition Hereditary angioedema