Compatibility of Stabilized Whole Blood Products with CD4 Technologies and Their Suitability for Quality Assessment Programs

Abstract

BackgroundCD4 T cell enumeration is the most widely used prognostic marker for management of HIV disease. Internal quality control and external quality assessment (EQA) programs are critical to ensure reliability of clinical measurements. The utility of stabilized whole blood products (SWBP) as a test reagent for EQA programs such as Quality Assessment and Standardization for Immunological measures relevant to HIV/AIDS (QASI) program have been demonstrated previously. Since then, several new commercial SWBPs and alternative CD4 enumeration technologies have become available. Seven SWBPs were evaluated on seven different enumeration platforms to determine which product(s) are most suitable for EQA programs that support multiple analytical technologies.MethodAssessment of SWBPs was based on two criteria: (1) accuracy of CD4 T cell measurements and; (2) stability under sub optimal storage conditions.ResultsThree SWBPs (Multi-Check, StatusFlow and CD4 Count) showed accurate CD4 T-cell absolute count and percentage values across six of the enumeration platforms. All products retain stability up to 18 days at 21–23°C with the exception of Multi-Check-high on FacsCount and Multi-Check-Low and StatusFlow-Low on Pima. One of the products (CD4 Count) retained stability for three days on all platforms tested when stored at 37°C.ConclusionThis study demonstrated that the characteristics of commercially available SWBPs vary across multiple CD4 platforms. The compatibility of testing panels for EQA programs with multiple analytical platforms needs to be carefully considered, especially in large multiplatform CD4 EQA programs. The selection of a suitable cross-platform SWBP is an increasing challenge as more reagents and platforms are introduced for CD4 T-cell enumeration.

Duplicate analysis method: a cheaper alternative to commercial IQC materials in limited resource settings for monitoring CD4 testing

“…FACSCount also sometimes failed to acquire these controls, especially IMMUNO-TROL controls, by giving a message of ‘Major tube failure’. Such testing failure due to inability to identify and gate clusters of cells of interest in case of fully automated platforms like FACSCount has also been reported in one of the studies [ 9 ]. Interestingly, the displays on Cyflow did not have much problem of poor separation as shown in Fig.…”

“…Setting of manual gates was found to be challenging because of poor separation of populations, requiring intense training of the staff. Such gating was also found to be subjective and unreliable at many times by other investigators also [ 9 ]. FACSCount also sometimes failed to acquire these controls, especially IMMUNO-TROL controls, by giving a message of ‘Major tube failure’.…”

“…1 . The stabilized blood samples have been shown to have altered light scatter and fluorescence staining properties as compared to fresh blood specimens, not satisfying the automatic gating algorithm defined by the instrument software [ 8 , 9 ]. Hence manual gating was required in case of FACSCalibur for analysis of stabilized blood samples.…”

Automation for clinical CD4 T‐cell enumeration, a desirable tool in the hands of skilled operators

“…Laboratories with poor performance are flagged for investigation and follow up. A laboratory performance qualifies as “poor” when the residual value (laboratory result—AGM) is greater than ± 3.0 points for percentage measurements and/or when percent differences ([lab residual/AGM]*100) from the AGM are greater than ± 15% for absolute count measurements. Root cause analysis is then performed and remedial action is implemented by the CIQAP team to prevent error recurrence.…”

Receptor occupancy assessment by flow cytometry as a pharmacodynamic biomarker in biopharmaceutical development

“…Stabilized blood specimens may provide valuable information on assay performance 52, 53. When stabilized blood is not suitable due to either deleterious effects on target receptor expression or loss of receptor‐expressing cells, other control specimens should be considered.…”