The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection may produce a systemic disease, the coronavirus disease-19 (COVID-19), with high morbidity and mortality. Even though we do not fully understand the interaction of innate and adaptive immunity in the control and complications of the viral infection, it is well recognized that SARS-CoV-2 induces an immunodepression that impairs the elimination of the virus and favors its rapid dissemination in the organism. Even less is known about the possible participation of inhibitory cells of the innate immune system, such as the myeloid-derived suppressor cells (MDSCs), or the adaptive immune system, such as the T regulatory cells (Tregs). That is why we aimed to study blood levels of MDSCs, as well as lymphocyte subpopulations, including Tregs, and activated (OX-40+) and inhibited (PD-1) T lymphocytes in patients with mild COVID-19 in comparison with data obtained from control donors. We have found that 20 hospitalized patients with COVID-19 and no health history of immunosuppression had a significant increase in the number of peripheral monocytic MDSCs (M-MDSC), but a decrease in Tregs, as well as an increase in the number of inhibited or exhausted T cells, whereas the number of activated T cells was significantly decreased compared with that from 20 healthy controls. Moreover, there was a significant negative correlation (r = 0.496) between the number of M-MDSC and the number of activated T cells. Therefore, M-MDSC rather than Tregs may contribute to the immunosuppression observed in patients with COVID-19.

中文翻译：

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轻度 COVID-19 患者血液单核细胞源性抑制细胞增加但调节性 T 淋巴细胞减少

严重急性呼吸系统综合症冠状病毒 2 (SARS-CoV-2) 感染可能会产生一种全身性疾病，即冠状病毒病 19 (COVID-19)，具有高发病率和死亡率。尽管我们不完全了解先天免疫和适应性免疫在病毒感染的控制和并发症中的相互作用，但众所周知，SARS-CoV-2 会诱导免疫抑制，从而削弱病毒的清除并有利于其在体内的快速传播。生物体。对先天免疫系统的抑制性细胞（如髓源性抑制细胞 (MDSC)）或适应性免疫系统（如 T 调节细胞 (Treg)）的可能参与知之甚少。这就是为什么我们旨在研究 MDSCs 以及淋巴细胞亚群（包括 Tregs、与从对照供体获得的数据相比，轻度 COVID-19 患者的 T 淋巴细胞被激活（OX-40+）和被抑制（PD-1）。我们发现，20 名 COVID-19 住院患者，没有免疫抑制病史，外周单核细胞 MDSC（M-MDSC）数量显着增加，但 Tregs 减少，抑制数量增加。或耗尽的 T 细胞，而与 20 名健康对照相比，活化 T 细胞的数量显着减少。此外，存在显着的负相关（我们发现，20 名 COVID-19 住院患者，没有免疫抑制病史，外周单核细胞 MDSC（M-MDSC）数量显着增加，但 Tregs 减少，抑制数量增加。或耗尽的 T 细胞，而与 20 名健康对照相比，活化 T 细胞的数量显着减少。此外，存在显着的负相关（我们发现，20 名 COVID-19 住院患者，没有免疫抑制病史，外周单核细胞 MDSC（M-MDSC）数量显着增加，但 Tregs 减少，抑制数量增加。或耗尽的 T 细胞，而与 20 名健康对照相比，活化 T 细胞的数量显着减少。此外，存在显着的负相关（r  = 0.496) 在 M-MDSC 的数量和激活的 T 细胞的数量之间。因此，在 COVID-19 患者中观察到的免疫抑制可能是 M-MDSC 而不是 Tregs。