Long-term preservation of antigenicity on tissue microarrays.

Author(s): DiVito KA, Charette LA, Rimm DL, Camp RL

Publication: Lab Invest, 2004, Vol. 84, Page 1071-8

PubMed ID: 15195116 PubMed Review Paper? No

Purpose of Paper

Conclusion of Paper

Studies

1. Study Purpose

   The purpose of this study was to determine if room temperature storage of FFPE tissue microarray sections alters estrogen receptor (ER) immunostaining. Of note, each storage time point is represented by a single section of a breast tissue microarray block.

   Summary of Findings:

   A statistically relevant reduction in ER staining was observed after 6 d of slide storage at room temperature compared to a freshly cut section, with a complete loss of immunostaining after 30 d.

   Biospecimens

   • Tissue - Breast

   Preservative Types

   • Formalin

   Diagnoses:

   • Neoplastic - Carcinoma

   Platform:

   Analyte	Technology Platform
   Protein	Immunohistochemistry
   Protein	Tissue microarray

   Pre-analytical Factors:

   Classification	Pre-analytical Factor	Value(s)
   Storage	Storage duration	2 d 6 d 30 d

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2. Study Purpose

   The purpose of this study was to assess the efficacy of FFPE tissue section storage methods on the preservation of ER, Ki-67, and cytokeratin antigencity. Ki-67 immunohistochemistry was performed on a tissue microarray comprised of breast, colon, and skin specimens.

   Summary of Findings:

   The observed loss of ER antigencity with room temperature FFPE tissue section storage was mitigated by coating TMA slides in paraffin and storage in a nitrogen desiccator, alone or in combination. The percentage of positive cases ER scoring in relation to freshly sectioned controls ranged from 61 to 99%; while manual versus automated scoring was a source of variation, both quantification techniques identified storage of paraffin-coated slides in a nitrogen desiccator as the superior preservation method. Cytokeratin and Ki-67 immunostaining were also significantly reduced after 3 months of room temperature storage with 88% and 52% reductions in immunostaining, respectively, compared to freshly cut TMA sections. Reductions in cytokeratin and Ki-67 immunostaining were partially attenuated by storage of FFPE tissue sections after paraffin coating or in a nitrogen desiccator, although combined methods (storage in a nitrogen desiccators after paraffin coating) proved to be the superior method of preservation, reducing antigencity loss to 4% and 28%, respectively. The addition of antioxidants to the paraffin coating (BHA and BHT) did not significantly affect immunostaining in comparison to untreated paraffin controls.

   Biospecimens

   • Tissue - Breast
   • Tissue - Skin
   • Tissue - Colorectal

   Preservative Types

   • Formalin

   Diagnoses:

   • Neoplastic - Carcinoma

   Platform:

   Analyte	Technology Platform
   Protein	Tissue microarray
   Protein	Immunohistochemistry

   Pre-analytical Factors:

   Classification	Pre-analytical Factor	Value(s)
   Storage	Storage duration	Fresh (unspecified duration) 3 months
   Biospecimen Aliquots and Components	Type of slide	Paraffin-coated slide Slide stored in a nitrogen dessicator Paraffin coated slide stored in a nitrogen dessicator Paraffin (with 1% BHA)- coated slide Paraffin (with 10% BHA)- coated slide Paraffin (with 1% BHT)- coated slide Paraffin (with 10% BHT)- coated slide
   Immunohistochemistry Specific	Targeted peptide/protein	ER Ki-67 Cytokeratin

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