Background: BCG vaccination is known to induce innate immune memory, which confers protection against heterologous infections. However, the effect of BCG vaccination on the conventional innate and adaptive immune cells subsets is not well characterized. Methods: We investigated the impact of BCG vaccination on the frequencies of T cell, B cell, monocyte and dendritic cell subsets as well as total antibody levels in a group of healthy elderly individuals (age 60-80 years) at one month post vaccination as part of our clinical study to examine the effect of BCG on COVID-19. Results: Our results demonstrate that BCG vaccination induced enhanced frequencies of central and effector memory CD4+ T cells and diminished frequencies of naive, transitional memory, stem cell memory CD4+ T cells and regulatory T cells. In addition, BCG vaccination induced enhanced frequencies of central, effector and terminal effector memory CD8+ T cells and diminished frequencies of naive, transitional memory and stem cell memory CD8+T cells. BCG vaccination also induced enhanced frequencies of immature, classical and activated memory B cells and plasma cells and diminished frequencies of naive and atypical memory B cells. While BCG vaccination did not induce significant alterations in monocytes subsets, it induced increased frequencies of myeloid and plasmacytoid DCs. Finally, BCG vaccination resulted in elevated levels of all antibody isotypes. Conclusions: BCG vaccination was associated with enhanced innate and adaptive memory cell subsets, as well as total antibody levels in elderly individuals, suggesting its potential utility in SARS-Cov2 infection by enhancing heterologous immunity.

中文翻译：

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卡介苗接种可诱导老年人记忆T和B细胞以及树突状细胞亚群的频率增加

背景：已知BCG疫苗可诱导先天免疫记忆，从而可以保护免受异源感染。但是，BCG疫苗接种对常规先天性和适应性免疫细胞亚群的影响尚不十分清楚。方法：我们调查了一组健康的老年人（年龄在60-80岁之间）在接种疫苗后一个月的时间里，卡介苗接种对T细胞，B细胞，单核细胞和树突状细胞亚群的频率以及总抗体水平的影响，临床研究的一部分，以检查卡介苗对COVID-19的作用。结果：我们的结果表明，卡介苗接种可诱导中枢和效应记忆CD4 + T细胞频率增加，而幼稚，过渡记忆，干细胞记忆CD4 + T细胞和调节性T细胞频率降低。此外，BCG疫苗接种可诱导中央，效应和终末效应记忆CD8 + T细胞的频率提高，而幼稚，过渡记忆和干细胞记忆CD8 + T细胞的频率降低。BCG疫苗接种还诱导了未成熟，经典和活化记忆B细胞和浆细胞的频率增加，以及幼稚和非典型记忆B细胞的频率降低。虽然BCG疫苗接种并未诱导单核细胞亚群的显着改变，但它诱导了髓样和浆细胞样DC的频率增加。最后，BCG疫苗接种导致所有抗体同种型水平升高。结论：BCG疫苗接种与增强的先天和适应性记忆细胞亚群以及老年人的总抗体水平有关，表明其通过增强异源免疫力可用于SARS-Cov2感染。