Background

Vaccines induce antigen-specific memory in adaptive immune cells that enables long-lived protection against the target pathogen. In addition to this, several vaccines have beneficial effects greater than protection against their target pathogen. These non-specific effects are proposed to be the result of vaccine-induced immunomodulation. In the case of bacille Calmette–Guérin (BCG) vaccine, this involves induction of innate immune memory, termed ‘trained immunity’, in monocytes and natural killer cells.

Objectives

This review discusses current evidence for vaccine-induced immunomodulation of adaptive immune cells and heterologous adaptive immune responses.

Content

The three vaccines that have been associated with changes in all-cause infant mortality: BCG, diphtheria–tetanus–pertussis (DTP) and measles-containing vaccines (MCV) alter T-cell and B-cell immunity. The majority of studies that investigated non-specific effects of these vaccines on the adaptive immune system report changes in numbers or proportions of adaptive immune cell populations. However, there is also evidence for effects of these vaccines on adaptive immune cell function and responses to heterologous stimuli. There is some evidence that, in addition to BCG, DTP and MCV, other vaccines (that have not been associated with changes in all-cause mortality) may alter adaptive immune responses to unrelated stimuli.

Implications

This review concludes that vaccines alter adaptive immune cell populations and heterologous immune responses. The non-specific effects differ between various vaccines and their effects on heterologous adaptive immune responses may also involve bystander activation, cross-reactivity and other as yet undefined mechanisms. This has major implications for future vaccine design and vaccination scheduling.

中文翻译：

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疫苗对异源适应性免疫的影响

背景

疫苗在适应性免疫细胞中诱导抗原特异性记忆，从而可以长期保护靶标病原体。除此之外，几种疫苗的有益作用还大于针对其目标病原体的保护作用。这些非特异性作用被认为是疫苗诱导的免疫调节的结果。就卡介苗（BCG）疫苗而言，这涉及在单核细胞和自然杀伤细胞中诱导先天免疫记忆，称为“训练免疫”。

目标

这篇综述讨论了疫苗诱导的适应性免疫细胞和异源适应性免疫反应的当前证据。

内容

与婴儿全因死亡率变化相关的三种疫苗：卡介苗，白喉-破伤风-百日咳（DTP）和含麻疹的疫苗（MCV）会改变T细胞和B细胞免疫。大多数研究这些疫苗对适应性免疫系统的非特异性作用的研究都报告了适应性免疫细胞群数量或比例的变化。但是，也有证据表明这些疫苗对适应性免疫细胞功能和对异源刺激的反应有影响。有证据表明，除了BCG，DTP和MCV外，其他疫苗（与全因死亡率的变化无关）可能会改变对无关刺激的适应性免疫反应。

含意

这项审查得出的结论是，疫苗会改变适应性免疫细胞群和异源免疫反应。不同疫苗之间的非特异性作用不同，它们对异源适应性免疫反应的作用也可能涉及旁观者激活，交叉反应和其他尚未确定的机制。这对未来的疫苗设计和疫苗接种计划具有重大影响。