Ann Lab Med.  2016 Jul;36(4):358-361. 10.3343/alm.2016.36.4.358.

Preparation of Internal Quality Control Material for Lymphocyte Subset Analysis

• Roh EY
• Shin S
• Yoon JH
• Oh S
• Park KU
• Lee N
• Song EY

• KMID: 2373556
• DOI: http://doi.org/10.3343/alm.2016.36.4.358

Abstract

Lymphocyte subset analysis is widely used in clinical laboratories, and more than two levels of daily QC materials are required for reliable results. Commercially available, expensive QC materials have short shelf lives and may not be suitable in resource-poor settings. We compared different methods for preparing homemade QC material, including fixation with 1%, 2%, or 4% paraformaldehyde (PFA); freezing with 10% dimethylsulfoxide (DMSO), 0.1% bovine serum albumin-phosphate buffered saline, or after ethanolic dehydration; and using cryopreservation temperatures of -20℃, -80℃, or -196℃. We found an optimal experimental condition, which is 'fixation with 4% PFA, freezing with 10% DMSO, and storage at 80℃'. To evaluate long-term stability of QC materials prepared in this optimal condition, two levels of QC materials (QM1 and QM2) were thawed after 30, 33, 35, 37, 60, 62, 64, and 67 days of cryopreservation. Lymphocyte subset was analyzed with BD Multitest IMK kit (BD Biosciences, USA). QM1 and QM2 were stable after 1-2 months of cryopreservation (CV <3% for CD3, CD4, and CD8 and 5-7% for CD16/56 and CD19). We propose this method as an alternative cost-effective protocol for preparing homemade internal QC materials for lymphocyte subset analysis in resource-poor settings.

Keyword

Peripheral blood; Lymphocyte subsets; Quality control; Material; Evaluation

MeSH Terms

Cryopreservation
Cryoprotective Agents/chemistry
*Flow Cytometry/standards
Lymphocyte Subsets/*cytology
Quality Control
Reagent Kits, Diagnostic
Time Factors
Cryoprotective Agents
Reagent Kits, Diagnostic

Figure

• 

  Fig. 1 Example dot plot showing lymphocyte subset analysis according to different preparation methods performed at day 4. (A) Paraformaldehyde concentration for fixation, (B) freezing method, and (C) cryopreservation temperature.Abbreviations: PFA, paraformaldehyde; DMSO, dimethyl sulfoxide; BSA-PBS, bovine serum albumin-phosphate buffered saline.

• 

  Fig. 2 Lymphocyte subset analysis after 30-67 days of cryopreservation in QM1 and QM2.Abbreviation: QM, quality control material.

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