Evaluation of a dry format reagent alternative for CD4 T‐cell enumeration for the FACSCount system: A report on a Moroccan–Canadian study

Abstract

Background: Efforts to improve alternative CD4 T-cell counting methods are critical to accelerate the implementation of HIV antiretroviral therapy in resources limited regions. Substituting liquid format reagents to eliminate cold-chain transportation and refrigerated storage with dry format reagents contributes to higher efficiency supply management solution especially for laboratories at remote locations. ReaMetrix has developed dry format reagent kits compatible with the FACSCount system, a dedicated flow cytometer for T-cell subset enumeration widely used in resource limited settings. A dual site collaborative study was designed to compare T-cell subsets using both the new dry format ReaMetrix reagent and the original BD Biosciences liquid reagents.Method: A total of 167 HIV positive samples prepared with Rea T Count (ReaMetrix) and FACSCount (BD Biosciences) reagents were analyzed using FACSCount Systems. To compare both methods, Bland-Altman, Pollock, Scott % similarity and correlation coefficient statistical analysis was applied. Immuno-Trol served as an assay processing control and quality indicator of interlaboratory and intralaboratory variation.Results: The mean bias and limits of agreement for CD4 T-cell measurements between Rea T Count and FACSCount reagents were 216 cells/ll (24.6%) and 274 to 143, respectively. The correlation obtained was 0.988 with a similarity of 97.9%. Between laboratory variation data was very good with %CV below 10%.Conclusion: The introduction of dry reagents permits the elimination of cold-chain transportation and the on-site refrigerated storage without compromise to assay quality. The substitution of dry reagents facilitates easier supply management practice that will assure wider access to quality HIV treatment. V C 2009 Clinical Cytometry Society

CD4 Enumeration Technologies: A Systematic Review of Test Performance for Determining Eligibility for Antiretroviral Therapy

“…At least one published performance evaluation study was found for each of the following technologies: BC Cytospheres [ 12 – 18 ], Dynal Dynabeads [ 14 , 18 – 22 ], Guava PCA [ 23 – 29 ], Partec CyFlow instruments [ 16 , 26 , 30 – 36 ], BD FACSCount [ 14 , 37 – 42 ]; BD Trucount tubes [ 43 – 46 ], BC Flow-Count fluorospheres [ 47 ], Cytognos Perfect-Count microspheres [ 48 ], SP Flow Cytometry using flow rate calibration [ 49 – 52 ]; BC PLG FlowCARE CD4 [ 53 ], Sysmex PocH-100i with Dynal Dynabeads [ 54 ], i+MED CD4 Select [ 55 ], Alere Pima Analyzer [ 56 – 58 , 61 ], PointCare NOW [ 60 ], Apogee Auto40 [ 59 , 63 , 64 ] and MBio Snap Count (MBio Diagnostics, Inc., Boulder, CO, USA [MBio]) [ 62 ].…”

Performance evaluation of the touchscreen-based Muse™ Auto CD4/CD4% single-platform system for CD4 T cell numeration in absolute number and in percentage using blood samples from children and adult patients living in the Central African Republic

“…The BD FACSCount system was used as reference system for CD4 T cell counting in the present evaluation. Indeed, the BD FACSCount is the oldest dedicated flow cytometer that has been extensively used since 1996 [32] and fully validated against reference flow cytometers in resource-limited settings [32–35]. …”

Monitoring CD4 in whole blood with an opto‐fluidic detector based on spatially modulated fluorescence emission

“…Below, we describe a microfluidic‐based technique that uses a small quantity of analyte and is able to detect and distinguish weakly emitting particles. For the future, our approach is fully compatible with the use of dried reagents [e.g., ReaMetrix/BD (13)] to further simplify sample preparation.…”