Validation and comparison of tumor-associated trypsin inhibitor (TATI) immunoassays.

Author(s): Janeiro E, Guimarães J, Stenman UH, Catarino M, Itkonen O

Publication: Clin Chim Acta, 2012, Vol. 413, Page 1244-8

PubMed ID: 22507084 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 patient age and gender, fasting prior to collection, collection tube type, storage, freeze-thaw cycling, and quantification platform on TATI concentrations in serum and the effects of collecting lithium-heparin plasma instead of serum on TATI levels. To determine the effect of long-term storage, TATI levels in 152 specimens stored at -70 degrees C for 9-11 years were compared to levels in 15 fresh specimens. For the freeze-thaw experiment no details of storage duration or thaw temperature or duration were included.

   Summary of Findings:

   TATI levels were significantly lower in specimens from women aged 31-50 years than those from 18-30 year old women (p=0.0115). In both men and women, TATI was higher serum from individuals over 70 years old than in serum from 51-70 year old patients (p=0.0005 and p=0.0001, respectively). Serum TATI levels were higher in specimens from 18-30 year old women than those from men of the same age (p<0.0001), but no other gender differences were observed. Fasting prior to blood draw, collecting lithium-heparin plasma rather than serum, and serum tube type had no effects on TATI concentrations. The authors report that when serum was stored for 4 weeks at 4 or 20 degrees C, TATI concentrations decreased from initial levels by 15.9% and 19.9%, respectively, but the authors did not note any differences observed at other timepoints. Similarly, the authors report that after 8 weeks at -80 degrees C, TATI concentrations decreased by 19% from initial levels, but they do not discuss other timepoints. Further, the authors report a 19.2% decline in TATI levels after serum was subjected to 4 freeze-thaw cycles at -20 degrees C. Specimens stored for 9-11 years at -70 degrees C had a mean TATI concentration that was 18% lower than the mean level in fresh specimens. The median TATI concentrations were 11.0, 13.5, and 16.0 ug/L using the RIA, IFMA and ELISA, respectively (p<0.0001, all). The intra-assay CVs using ELISA and IFMA were 7.1% and 9.7%, respectively, at 9.5 ug/L and 9.1% and 3.5%, respectively, at 18.8 ug/L. Further, recovery of TATI from spiked serum was less than 87.7-98.7% using IFMA, but 100-117% using ELISA.

   Biospecimens

   • Bodily Fluid - Plasma
   • Bodily Fluid - Serum
   • Bodily Fluid - Blood

   Preservative Types

   • None (Fresh)
   • Frozen

   Diagnoses:

   • Normal

   Platform:

   Analyte	Technology Platform
   Protein	ELISA
   Protein	Radioimmunoassay
   Protein	Immunoassay

   Pre-analytical Factors:

   Classification	Pre-analytical Factor	Value(s)
   Preaquisition	Patient gender	Female Male
   Preaquisition	Patient age	18-30 years 31-50 years 51-70 years >70 years
   Biospecimen Acquisition	Type of collection container/solution	Glass tube Clotting catalyzator tube SST II advance tube Lithium-heparin tube
   Biospecimen Acquisition	Time of biospecimen collection	Before eating After Finish breakfast
   Biospecimen Aliquots and Components	Blood and blood products	Plasma Serum
   Biospecimen Preservation	Type of fixation/preservation	Frozen None (fresh)
   Storage	Storage temperature	4 degrees C -20 degrees C -70 degrees C -80 degrees C
   Storage	Storage duration	0 days 1 week 2 weeks 4 weeks 8 weeks 9-11 years
   Immunoassay Specific	Technology platform	TR-IFMA ELISA RIA

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