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.

Christian Diamant Mossoro-Kpinde,Edouard Kokanzo,Gérard Grésenguet,Jean De Dieu Longo,Rosine Féissona,André Kouabosso,Ralph-Sydney Mboumba Bouassa,Laurent Bélec

doi:10.1186/s12967-016-1082-7

Abstract

BackgroundThe new microcapillary and fluorescence-based EC IVD-qualified Muse™ Auto CD4/CD4% single-platform assay (EMD Millipore Corporation, Merck Life Sciences, KGaA, Darmstadt, Germany) for CD4 T cell numeration in absolute number and in percentage was evaluated using Central African patients’ samples compared against the reference EC IVD-qualified BD FACSCount (Becton–Dickinson, USA) flow cytometer.MethodsEDTA-blood samples from 124 adults, 10 adolescents, 13 children and 3 infants were tested in parallel at 2 reference laboratories in Bangui.ResultsThe Muse™ technique was highly reproducible, with low intra- and inter-run variabilities less than 15%. CD4 T cell counts of Muse™ and BD FACSCount in absolute number and percentage were highly correlated (r2 = 0.99 and 0.98, respectively). The mean absolute bias between Muse™ and BD FACSCount cells in absolute number and percentage were −5.91 cells/µl (95% CI −20.90 to 9.08) with limits of agreement from −77.50 to 202.40 cells/µl, and +1.69 %CD4 (95% CI ±1.29 to +2.09), respectively. The percentages of outliers outside the limits of agreement were nearly similar in absolute number (8%) and percentage (10%). CD4 T cell counting by Muse™ allowed identifying the majority of individuals with CD4 T cell <200, <350 or <750 cells/µl corresponding to the relevant thresholds of therapeutic care, with sensitivities of 95.5–100% and specificities of 83.9–100%.ConclusionsThe Muse™ Auto CD4/CD4% Assay analyzer is a reliable alternative flow cytometer for CD4 T lymphocyte enumeration to be used in routine immunological monitoring according to World Health Organization recommendations in HIV-infected adults as well as children living in resource-constrained settings.

Highlights

The new microcapillary and fluorescence-based EC IVD-qualified MuseTM Auto CD4/CD4% singleplatform assay (EMD Millipore Corporation, Merck Life Sciences, KGaA, Darmstadt, Germany) for CD4 T cell numeration in absolute number and in percentage was evaluated using Central African patients’ samples compared against the reference EC IVD-qualified BD FACSCount (Becton–Dickinson, USA) flow cytometer
CD4 T cell counting remains currently an important biological marker for antiretroviral treatment (ART) monitoring for at least 4 major reasons: (1) The marker is well known to physicians and largely implemented throughout Africa; (2) World Health Organization (WHO) thresholds for ART initiation as a priority remains based on CD4 T cell enumeration while ART is not universally available; (3) Immunological failure may be important to diagnose in order to confirm therapeutic failure by targeted HIV-1 viral load when HIV load is not universally implemented; and (4) CD4 T cell levels are important to determine the prophylaxis of opportunistic infections
For CD4 T cell expressed in absolute number, the mean intra-assay coefficient of variance (CV) of MuseTM Auto CD4/CD4% system was 8.5%; the inter-assay CVs of the analyzer appeared slightly higher than intrarun CVs for CD4 T cell counts below 350 cells/μl, with a mean interrun variability of 10.4%

Summary

Introduction

The new microcapillary and fluorescence-based EC IVD-qualified MuseTM Auto CD4/CD4% singleplatform assay (EMD Millipore Corporation, Merck Life Sciences, KGaA, Darmstadt, Germany) for CD4 T cell numeration in absolute number and in percentage was evaluated using Central African patients’ samples compared against the reference EC IVD-qualified BD FACSCount (Becton–Dickinson, USA) flow cytometer. A comprehensive revision of the WHO guidelines on the use of ART has been undertaken in 2015 and based on new scientific evidence and lessons from antiretroviral programs implementation [6] and recently consolidated in 2016 [7]. The HIV-1 RNA load remains the principal biological marker to monitor ART efficacy and early therapeutic failure [6, 7]. CD4 T cell counting remains currently an important biological marker for ART monitoring for at least 4 major reasons: (1) The marker is well known to physicians and largely implemented throughout Africa; (2) WHO thresholds for ART initiation as a priority remains based on CD4 T cell enumeration while ART is not universally available; (3) Immunological failure may be important to diagnose in order to confirm therapeutic failure by targeted HIV-1 viral load when HIV load is not universally implemented; and (4) CD4 T cell levels are important to determine the prophylaxis of opportunistic infections. CD4 T cell counting will remain an important biological marker for ART during the few years

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