AlphaLISA versus ELISA-based detection of interleukin 18 in healthy subjects and patients with end-stage renal disease.

Author(s): Peters CD, Jespersen B, Nørregaard R

Publication: Scand J Clin Lab Invest, 2012, Vol. 72, Page 583-92

PubMed ID: 22935048 PubMed Review Paper? No

Purpose of Paper

Conclusion of Paper

Studies

1. Study Purpose

   The purpose of this study was to determine the effects of whole blood storage temperature and duration, freeze-thaw cycling, hemolysis, plasma additives and assay type on IL-18 concentrations in plasma from healthy volunteers and patients with end-stage renal disease (ESRD). All plasma specimens were stored at -80 degrees C prior to analysis.

   Summary of Findings:

   While storing blood specimens for up to 24 h at 5 degrees C had no effect on IL-18 concentrations in plasma, significant declines in plasma IL-18 were noted after room temperature storage of blood (24 h versus 0 or 1 h, and 6 versus 1 h, all p<0.05). Subjecting plasma to up to 6 freeze-thaw cycles, low levels of hemolysis or adding phosphate buffer or mouse IgG had no effects on IL-18 levels, but severe hemolysis or adding mouse serum increased mean IL-18 levels (p=0.0040 and p=0.036, respectively). After storing plasma for 0-424 days at -80 degrees C, the CV of IL-18 in plasma was 8.8% when assayed by ELISA. However, storing plasma for 0-312 days at -80 degrees C resulted in a CV of 59.2% when plasma IL-18 was assayed by AlphaLISA. The intraassay, interassay, and batch to batch CVs for IL-18, as well as the detection limits, were all higher by AlphaLISA than by ELISA, and IL-18 concentrations were higher when measured by AlphaLISA than by ELISA. Using both methods, IL-18 levels were significantly higher in patients with ESRD than in healthy volunteers (p<0.0005).

   Biospecimens

   • Bodily Fluid - Blood
   • Bodily Fluid - Plasma

   Preservative Types

   • Frozen

   Diagnoses:

   • Other diagnoses
   • Normal

   Platform:

   Analyte	Technology Platform
   Protein	ELISA
   Protein	Chemiluminescence immunoassay

   Pre-analytical Factors:

   Classification	Pre-analytical Factor	Value(s)
   Preaquisition	Diagnosis/ patient condition	End-stage renal disease Healthy
   Storage	Storage temperature	-80 degrees C 5 degrees C Room temperature
   Storage	Storage duration	0 h 1 h 6 h 24 h 0-312 h 0-424 h
   Biospecimen Aliquots and Components	Blood and blood products	Plasma Whole blood
   Biospecimen Aliquots and Components	Hemolysis	Freeze/thaw-induced Not induced Pipette tip-induced
   Biospecimen Aliquots and Components	Biospecimen components	Phosphate buffer added Mouse serum added Polyclonal mouse IgG added No additive
   Storage	Freeze/thaw cycling	1 cycle 2 cycles 3 cycles 4 cycles 5 cycles 6 cycles
   ELISA Specific	Technology platform	AlphaLISA
   Biospecimen Aliquots and Components	Centrifugation	Centrifugation delays investigated

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