title: Preparation of Internal Quality Control Material for Lymphocyte Subset Analysis.
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°C, -80°C, or -196°C. We found an optimal experimental condition, which is 'fixation with 4% PFA, freezing with 10% DMSO, and storage at 80°C'. 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.
authors.affiliation: Department of Laboratory Medicine, Seoul National University College of Medicine, Seoul, Korea.|Department of Laboratory Medicine, Seoul National University Boramae Medical Center, Seoul, Korea.
authors.forename: Eun Youn
authors.initials: EY
authors.lastname: Roh
authors.affiliation: Department of Laboratory Medicine, Seoul National University College of Medicine, Seoul, Korea.|Department of Laboratory Medicine, Seoul National University Boramae Medical Center, Seoul, Korea.
authors.forename: Sue
authors.initials: S
authors.lastname: Shin
authors.affiliation: Department of Laboratory Medicine, Seoul National University College of Medicine, Seoul, Korea.|Department of Laboratory Medicine, Seoul National University Boramae Medical Center, Seoul, Korea.
authors.forename: Jong Hyun
authors.initials: JH
authors.lastname: Yoon
authors.affiliation: Department of Biostatistics, Seoul National University Boramae Medical Center, Seoul, Korea.
authors.forename: Sohee
authors.initials: S
authors.lastname: Oh
authors.affiliation: Department of Laboratory Medicine, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Kyoung Un
authors.initials: KU
authors.lastname: Park
authors.affiliation: Department of Laboratory Medicine, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Nuri
authors.initials: N
authors.lastname: Lee
authors.affiliation: Department of Laboratory Medicine, Seoul National University College of Medicine, Seoul, Korea.|Department of Molecular Medicine and Biopharmaceutical Sciences, Graduate School of Convergence Science and Technology and College of Medicine, Medical Research Center, Seoul National University, Seoul, Korea. eysong1@snu.ac.kr.
authors.forename: Eun Young
authors.initials: EY
authors.lastname: Song
mesh_terms: D015925:Cryopreservation; D003451:Cryoprotective Agents / Q000737:chemistry; D005434:Flow Cytometry / Q000592:standards; D016131:Lymphocyte Subsets / Q000166:cytology*; D011786:Quality Control; D011933:Reagent Kits, Diagnostic; D013997:Time Factors
chemical_list: D003451:Cryoprotective Agents; D011933:Reagent Kits, Diagnostic
keywords: Evaluation; Lymphocyte subsets; Material; Peripheral blood; Quality control