Florida Atlantic University, Charles E. Schmidt College of Medicine, Department of Medicine, 777 Glades Road, PO Box 3091, Boca Raton, FL 33431, USA.
Florida Atlantic University, Charles E. Schmidt College of Medicine, Department of Medicine, 777 Glades Road, PO Box 3091, Boca Raton, FL 33431, USA.
J Immunol Methods. 2024 Apr;527:113650. doi: 10.1016/j.jim.2024.113650. Epub 2024 Feb 28.
Current methodologies for assessing vaccine effectiveness and longevity primarily center on measuring vaccine-induced neutralizing antibodies in serum or plasma. However, these methods overlook additional parameters such as the presence of memory B cells, even as antibody levels wane, and the pivotal role played by memory T cells in shaping antigen-specific memory B cell responses. Several studies have employed a combination of polyclonal activators, such as CpG and R848, along with various cytokines to provoke the recall of memory B cells from peripheral blood mononuclear cells (PBMCs) into antibody-secreting cells (ASCs). Other studies have examined the use of live attenuated viruses to stimulate antigen-specific memory T cells within PBMCs into effector T cells that produce Th1/Th2 cytokines. However, these studies have not fully elucidated the distinct effects of these polyclonal activators on individual subsets, nor have they evaluated whether the vaccine antigen alone is sufficient to trigger the recall of memory T cells. Thus, in this study, we directly compared the capacity of two B cell polyclonal activators to induce the transition of existing vaccine-specific memory cells present in peripheral blood samples into ASCs. Simultaneously, we also assessed the transition of existing memory T cells into effector subsets in response to vaccine antigens. Our findings demonstrate that both polyclonal activator combinations, CpG with IL-6 and IL-15, as well as R848 with IL-2, effectively induce the terminal differentiation of memory B cells into ASCs. Notably, CpG treatment preferentially expanded naïve and non-class-switched B cells, while R848 expanded class-switched memory cells, plasmablasts, and plasma cells. Consequently, R848 treatment led to a greater overall production of total and antigen-specific IgG immunoglobulins. Additionally, the exposure of isolated PBMCs to vaccine antigens alone proved sufficient for recalling the rare antigen-specific memory T cells into effector subsets, predominantly consisting of IFN-γ-producing CD4 T cells and TNF-β-producing CD8 T cells. This study not only establishes a rationale for the selection of methods to expand and detect antigen-specific lymphocyte subsets but also presents a means to quantify vaccine effectiveness by correlating serum antibody levels with preexisting memory cells within peripheral blood samples.
目前评估疫苗效力和持久性的方法主要集中在测量血清或血浆中疫苗诱导的中和抗体。然而，这些方法忽略了其他参数，如记忆 B 细胞的存在，即使抗体水平下降，以及记忆 T 细胞在塑造抗原特异性记忆 B 细胞反应中的关键作用。几项研究采用了多克隆激活剂的组合，如 CpG 和 R848，以及各种细胞因子，从外周血单核细胞 (PBMC) 中召回记忆 B 细胞成为分泌抗体的细胞 (ASCs)。其他研究检查了使用活减毒病毒刺激 PBMC 内的抗原特异性记忆 T 细胞成为产生 Th1/Th2 细胞因子的效应 T 细胞。然而，这些研究尚未完全阐明这些多克隆激活剂对单个亚群的不同影响，也没有评估单独的疫苗抗原是否足以触发记忆 T 细胞的召回。因此，在这项研究中，我们直接比较了两种 B 细胞多克隆激活剂诱导存在于外周血样本中的现有疫苗特异性记忆细胞转化为 ASC 的能力。同时，我们还评估了现有记忆 T 细胞对疫苗抗原的反应转化为效应亚群的情况。我们的研究结果表明，CpG 与 IL-6 和 IL-15 以及 R848 与 IL-2 的两种多克隆激活剂组合都能有效地诱导记忆 B 细胞终末分化为 ASC。值得注意的是，CpG 处理优先扩增了幼稚和未转换的 B 细胞，而 R848 则扩增了转换的记忆细胞、浆母细胞和浆细胞。因此，R848 处理导致总和抗原特异性 IgG 免疫球蛋白的产生量增加。此外，单独暴露于疫苗抗原的分离 PBMC 足以召回罕见的抗原特异性记忆 T 细胞成为效应亚群，主要由 IFN-γ 产生的 CD4 T 细胞和 TNF-β 产生的 CD8 T 细胞组成。这项研究不仅为选择方法来扩增和检测抗原特异性淋巴细胞亚群提供了依据，而且还提供了一种通过将血清抗体水平与外周血样本中预先存在的记忆细胞相关联来量化疫苗效力的方法。
