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

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 eta = 0.08) when compared to DPFC than for the Cyto-Spheres method (r = 0.725 and eta = 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 (r(2) = 0.864 and r(2) = 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.