Vaccine Research Center, National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Bethesda, MD, United States.
Nonhuman Primate Reagent Resource, University of Massachusetts Chan Medical School, Worcester, MA, United States.
Front Immunol. 2024 Mar 11;15:1359679. doi: 10.3389/fimmu.2024.1359679. eCollection 2024.
Understanding the immunological control of pathogens requires a detailed evaluation of the mechanistic contributions of individual cell types within the immune system. While knockout mouse models that lack certain cell types have been used to help define the role of those cells, the biological and physiological characteristics of mice do not necessarily recapitulate that of a human. To overcome some of these differences, studies often look towards nonhuman primates (NHPs) due to their close phylogenetic relationship to humans. To evaluate the immunological role of select cell types, the NHP model provides distinct advantages since NHP more closely mirror the disease manifestations and immunological characteristics of humans. However, many of the experimental manipulations routinely used in mice (e.g., gene knock-out) cannot be used with the NHP model. As an alternative, the infusion of monoclonal antibodies that target surface proteins on specific cells to either functionally inhibit or deplete cells can be a useful tool. Such depleting antibodies have been used in NHP studies to address immunological mechanisms of action. In these studies, the extent of depletion has generally been reported for blood, but not thoroughly assessed in tissues. Here, we evaluated four depleting regimens that primarily target T cells in NHP: anti-CD4, anti-CD8α, anti-CD8β, and immunotoxin-conjugated anti-CD3. We evaluated these treatments in healthy unvaccinated and IV BCG-vaccinated NHP to measure the extent that vaccine-elicited T cells - which may be activated, increased in number, or resident in specific tissues - are depleted compared to resting populations in unvaccinated NHPs. We report quantitative measurements of depletion at multiple tissue sites providing insight into the range of cell types depleted by a given mAb. While we found substantial depletion of target cell types in blood and tissue of many animals, residual cells remained, often residing within tissue. Notably, we find that animal-to-animal variation is substantial and consequently studies that use these reagents should be powered accordingly.
理解病原体的免疫控制需要详细评估免疫系统中单个细胞类型的机制贡献。虽然缺乏某些细胞类型的敲除小鼠模型已被用于帮助定义这些细胞的作用，但小鼠的生物学和生理学特征并不一定能再现人类的特征。为了克服这些差异中的一些，由于与人类具有密切的系统发育关系，研究人员经常关注非人类灵长类动物（NHP）。为了评估特定细胞类型的免疫学作用，NHP 模型提供了明显的优势，因为 NHP 更能模拟人类的疾病表现和免疫学特征。然而，许多在小鼠中常规使用的实验操作（例如基因敲除）不能用于 NHP 模型。作为替代方案，可以使用针对特定细胞表面蛋白的单克隆抗体来输注，以实现对细胞的功能抑制或耗竭，这是一种有用的工具。这种耗竭抗体已在 NHP 研究中用于解决作用机制的免疫学问题。在这些研究中，通常会报告血液中耗竭的程度，但在组织中并未进行彻底评估。在这里，我们评估了四种主要靶向 NHP 中的 T 细胞的耗竭方案：抗 CD4、抗 CD8α、抗 CD8β 和免疫毒素偶联的抗 CD3。我们评估了这些治疗方案在健康未接种疫苗和 IV BCG 接种的 NHP 中的效果，以衡量与未接种疫苗的 NHP 中的静止群体相比，疫苗诱导的 T 细胞（可能被激活、数量增加或驻留在特定组织中）的耗竭程度。我们报告了多个组织部位的耗竭定量测量结果，为了解特定 mAb 耗竭的细胞类型范围提供了深入的见解。虽然我们发现许多动物的血液和组织中目标细胞类型的耗竭程度很大，但仍有残留细胞，这些细胞通常驻留在组织内。值得注意的是，我们发现动物间的变异性很大，因此使用这些试剂的研究应该相应地进行功率计算。
