Immunology Unit, Laboratory of Bacteriology-Virology, CHU Le Dantec University Teaching Hospital, BP 7325 Dakar, Senegal.
J Immunol Methods. 2011 Sep 30;372(1-2):7-13. doi: 10.1016/j.jim.2011.07.012. Epub 2011 Jul 29.
Laboratory follow-up of HIV patients in resource-limited settings requires appropriate instruments for CD4 T cell enumeration. In this study, we evaluated the application of a simplified, mobile and robust flow cytometry system, the Apogee Auto 40 analyzer (Auto40) using thermoresistant reagents, for CD4 T cell enumeration. We measured the absolute CD4 counts in fresh whole blood samples from 170 Senegalese subjects, including 129 HIV-positive (HIV+) patients and 41 HIV-negative (HIV-) controls. Based on volumetric primary CD4 gating, cells were stained with commercially available reagents (Easy MoAb CD4;Bio-D, Valenzano, Italy) and analyzed on the Auto40. The results were compared with those from the FACSCount system (Becton Dickinson, San Jose, USA). Repeatability analysis was performed on duplicate testing of 49 samples on both FACSCount and Auto40. The intra-run precision was measured by 10 replicates using 3 clinical blood samples with low, intermediate and high CD4 concentrations. The results from the two instruments were in good agreement. The percent similarity between the results of both instruments was 99%±relative standard deviation of 12.7%. The concordance correlation coefficient was 0.99. The absolute bias and limits of agreement (LOA) between the two instruments, calculated by Bland-Altman analysis, were clinically acceptable (bias: +4 cells/μl; LOA: -111 to +120 cells/μl). The clinical agreement between the two instruments at a cutoff of 200 CD4 cells/μl was 94%. The repeatability of measurements on the Auto40 was also similar to that observed with FACSCount system (bias +0.1 cells/μl, coefficient of variation 2.5% vs bias -1.1cells/μl, coefficient of variation 2.9% respectively). In conclusion, our results indicate that the Auto 40 system, using thermoresistant reagents, is suitable for CD4 T cell enumeration and will be a helpful tool to improve HIV laboratory monitoring in resource-limited settings.
在资源有限的环境中，对 HIV 患者进行实验室随访需要使用适当的 CD4 T 细胞计数仪器。在这项研究中，我们评估了使用一种简化的、移动的和强大的流式细胞仪系统——Apogee Auto 40 分析仪（Auto40），该系统使用耐热试剂，对 CD4 T 细胞进行计数。我们测量了 170 名塞内加尔受试者新鲜全血样本中的绝对 CD4 计数，其中包括 129 名 HIV 阳性（HIV+）患者和 41 名 HIV 阴性（HIV-）对照。基于体积初级 CD4 门控，使用商业上可获得的试剂（Easy MoAb CD4；Bio-D，瓦伦扎诺，意大利）对细胞进行染色，并在 Auto40 上进行分析。结果与 FACSCount 系统（Becton Dickinson，圣何塞，美国）的结果进行了比较。对 FACSCount 和 Auto40 上 49 个样本的重复测试进行了重复性分析。通过使用 3 个具有低、中和高 CD4 浓度的临床血液样本进行 10 次重复测量，评估了运行内精度。两种仪器的结果具有良好的一致性。两种仪器结果的相似度为 99%±相对标准偏差为 12.7%。一致性相关系数为 0.99。通过 Bland-Altman 分析计算的两种仪器之间的绝对偏差和（LOA）界限是可接受的（偏差：+4 个/μl；LOA：-111 至+120 个/μl）。两种仪器在 200 个 CD4 细胞/μl 截止值下的临床一致性为 94%。Auto40 上的测量重复性也与 FACSCount 系统相似（偏差+0.1 个/μl，变异系数为 2.5%；偏差-1.1 个/μl，变异系数为 2.9%）。总之，我们的结果表明，使用耐热试剂的 Auto 40 系统适用于 CD4 T 细胞计数，将成为改善资源有限环境中 HIV 实验室监测的有用工具。
