Serum microarrays for large scale screening of protein levels.

Author(s): Janzi M, Odling J, Pan-Hammarström Q, Sundberg M, Lundeberg J, Uhlén M, Hammarström L, Nilsson P

Publication: Mol Cell Proteomics, 2005, Vol. 4, Page 1942-7

PubMed ID: 16131484 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 analysis method and freeze-thaw cycling on serum IgA and C3 concentrations. Specimens were collected between 1999 and 2002 and stored at -20 degrees C.

   Summary of Findings:

   One freeze-thaw cycle led to significant deviations in IgA measurements which were larger for specimens with lower initial IgA concentrations (56% for <0.07 mg/mL IgA) than for specimens with higher initial IgA concentrations (12% for >0.07-4.9 mg/mL IgA and 31% for >5 mg/mL IgA). However, the authors note that the lower concentrations of IgA were initially measured by radial immunodiffusion which has a lower limit of detection than nephelometry which was used for measurement after the freeze-thaw cycle. Nephelometric determination of IgA at high concentrations (>5 mg/mL) showed increased variation, and these specimens were excluded from analysis. The authors state that a high level of correlation was observed between serum microarray and nephelometric analysis of serum IgA levels. 65 of 1964 specimens (3.3%) showed greater than 5-fold deviation between IgA measurements taken by each method. 31 of these specimens had higher values on the array, but very low measurements (median 0.02 mg/mL) and 34 had higher values by nephelometry. Similar correlations between serum microarray and nephelometric analysis were observed for the measurement of C3.

   Biospecimens

   • Bodily Fluid - Serum

   Preservative Types

   • Frozen

   Diagnoses:

   • Other diagnoses
   • Not specified

   Platform:

   Analyte	Technology Platform
   Protein	Reverse phase protein microarray
   Protein	Radial immunodiffusion assay
   Protein	Clinical chemistry/auto analyzer

   Pre-analytical Factors:

   Classification	Pre-analytical Factor	Value(s)
   Preaquisition	Diagnosis/ patient condition	Increased susceptibility to infection
   Preaquisition	Biomarker level	Increased IgA levels Normal IgA levels Low IgA levels
   Reverse phase protein microarray Specific	Targeted peptide/protein	IgA C3
   Clinical chemistry/auto analyzer Specific	Technology platform	Radial immunodiffusion assay Serum microarray
   Storage	Freeze/thaw cycling	0 cycles 1 cycle

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