Fei D T, Paxton H, Chen A B
Department of Medicinal and Analytical Chemistry, Genentech, Inc., South San Francisco, CA 94080.
Biologicals. 1993 Sep;21(3):221-31. doi: 10.1006/biol.1993.1079.
Maintenance of CD4+ T helper lymphocyte counts has been used as a surrogate marker of efficacy for drugs in the treatment of AIDS. In a multicenter clinical trial, subtle improvement of CD4+ T cell counts may be masked and misinterpreted if care is not paid to likely sources that can contribute to the variability of measurement of CD4+ T lymphocytes. This review addresses major areas that can contribute to the variability of measurement of CD4+ T lymphocytes, with emphasis on applications to multicenter clinical trials, and proposes areas of improvement that may not be well recognized by the medical community. Whereas there are excellent guidelines for immunophenotyping, equal attention is needed in hematologic enumeration of WBC and absolute lymphocytes. In particular, allowing the margin of error acceptable to blood cell standards for HIV-infected specimens is unsatisfactory. Special attention should also be given to the stability of lymphocytes in the anticoagulant during storage, the lysing method, the quality assurance programs as well as intrasubject fluctuations which may be derived from exercise, medications and diurnal variations. Awareness of these contributing factors by physicians and technical analysts will expedite the discovery of potential therapy in the treatment of AIDS. For a multicenter clinical trial, it is advisable to select a centralized laboratory adopting a uniform protocol with regard to sample preparation and handling, using more stringent quality controls for hematologic analysers, calibration of instruments and immunophenotyping. Pending a true reference standard that can monitor the variation of the entire analytical procedure, we anticipate that future interlaboratory quality assurance programs will include absolute T lymphocyte count, an important parameter for assessing the accuracy and consistency of CD4+ T helper cell counts generated from a laboratory.
维持 CD4+ T 辅助淋巴细胞计数一直被用作治疗艾滋病药物疗效的替代指标。在一项多中心临床试验中，如果不注意可能导致 CD4+ T 淋巴细胞测量值变异的潜在来源，CD4+ T 细胞计数的细微改善可能会被掩盖并误判。本综述探讨了可能导致 CD4+ T 淋巴细胞测量值变异的主要方面，重点是在多中心临床试验中的应用，并提出了医学界可能尚未充分认识到的改进领域。虽然免疫表型分析有出色的指南，但白细胞和绝对淋巴细胞的血液学计数也需要同样关注。特别是，对于 HIV 感染样本，采用血细胞标准可接受的误差范围并不理想。还应特别关注淋巴细胞在储存期间抗凝剂中的稳定性、裂解方法、质量保证程序以及可能由运动、药物和昼夜变化引起的个体内波动。医生和技术分析人员了解这些影响因素将加快艾滋病治疗中潜在疗法的发现。对于多中心临床试验，建议选择一个集中实验室，在样本制备和处理方面采用统一方案，对血液分析仪使用更严格的质量控制、仪器校准和免疫表型分析。在有能够监测整个分析过程变异的真正参考标准之前，我们预计未来的实验室间质量保证计划将包括绝对 T 淋巴细胞计数，这是评估实验室产生的 CD4+ T 辅助细胞计数准确性和一致性的重要参数。
