Comparison of two alternative methods for CD4+ T‐cell determination (Coulter manual CD4 count and CyFlow) against standard dual platform flow cytometry in Uganda

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Abstract
Background In this study we evaluated alternative CD4+ T‐cell counting methods in clients of a PMTCT Programme in rural Uganda. Methods The Coulter Manual CD4 Count method for CD4+ T‐cell enumeration (Cyto‐Spheres) and an automated method (volumetric, single‐platform flow cytometry; CyFlow) were compared with a standard, dual‐platform flow cytometry protocol (DPFC, FACScan). Results Correlation and precision of agreement were higher for the CyFlow method (r = 0.929 and η = 0.08) when compared to DPFC than for the Cyto‐Spheres method (r = 0.725 and η = 0.3). Multiple linear regression analysis showed that CD4+ cell counts by the CyFlow method were a stronger predictor for results of DPFC than those of the Cyto‐Spheres method (r2 = 0.864 and r2 = 0.552, respectively). When compared to DPFC the CyFlow method generated higher CD4+ cell counts than the Cyto‐Spheres method, as expressed by a higher median and mean difference (+70 and +90 cells for CyFlow, +28 and −1.4 cells for Cyto‐Spheres). Conclusion Both, the manual Cyto‐Spheres method and the CyFlow method can be used for the enumeration of CD4+ cells in resource‐limited settings. Under supervised conditions, the CyFlow method produced results more consistent with the reference method than the Cyto‐Spheres method. © 2006 International Society for Analytical Cytology