Research Center for Immunodeficiencies, Children's Medical Center Hospital, Tehran University of Medical Sciences, Tehran, Iran.
Systematic Review and Meta-analysis Expert Group (SRMEG), Universal Scientific Education and Research Network (USERN), Tehran, Iran.
Adv Exp Med Biol. 2021;1318:119-147. doi: 10.1007/978-3-030-63761-3_8.
The novel coronavirus disease (COVID-19) profoundly influences T-cell immunity. The counts of total T cells and T-cell subsets, especially CD4+ and CD8+ T cells, are decreased in patients with COVID-19. Also, the function of these cells becomes less effective as the expression of immune inhibitory receptors, such as Tim3 and PD-1, increases over time during the disease. Kinetic analyses show that the T-cell profile changes dynamically, so does the COVID-19 stages. As COVID-19 continues to deteriorate and progresses to severe/critical condition, the lymphocyte count steadily decreases. Therefore, the ability of COVID-19 to escape the immune system might lie in its power to profoundly diminish T-cell effective function, which is necessary for the establishment of a robust antiviral immunity. Also, COVID-19 is associated with increased numbers of monocytes and macrophages, and as the disease progresses from a mild form to a severe/critical condition, the macrophage population becomes denser. Monitoring the expression of cytokines associated with macrophage activation, mainly interleukin (IL)-6 and IL-10, indicates that the course of COVID-19 consists of two stages and the transition between disease stages occurs by the end of the first week after onset of symptoms. At the initial stage, the immune military recognizes the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) as nonself and thus fires macrophages at the lungs against the virus. The first flame can control disease progression effectively. However, a trained immunocompetent system would maintain the fire of macrophages over an extended time. It lies in its immune memory in tissue-resident macrophages, especially alveolar macrophages, making a professionally trained immune system more likely to be feared by COVID-19 than an untrained immune system. In this manner, the trained immunocompetent system commits such a failure that causes the lungs to come down rapidly. The fact that younger age groups, including neonates and children, are less susceptible to COVID-19 than older age groups reflects that the natural affinities of the immune system that has not been trained thoroughly would be standard in combatting against COVID-19 whereas the higher affinities of the trained immune system for rapid activation of immune responses might raise faults - the lungs come down.
新型冠状病毒病（COVID-19）深刻地影响了 T 细胞免疫。COVID-19 患者的总 T 细胞和 T 细胞亚群（尤其是 CD4+和 CD8+T 细胞）计数下降。此外，随着疾病的发展，这些细胞的功能变得不那么有效，因为免疫抑制受体（如 Tim3 和 PD-1）的表达会增加。动力学分析表明，T 细胞谱随着 COVID-19 阶段的变化而动态变化。随着 COVID-19 的持续恶化和进展为严重/危重症，淋巴细胞计数稳步下降。因此，COVID-19 逃避免疫系统的能力可能在于其深刻降低 T 细胞有效功能的能力，这对于建立强大的抗病毒免疫是必要的。此外，COVID-19 与单核细胞和巨噬细胞数量的增加有关，并且随着疾病从轻度形式进展为严重/危重症，巨噬细胞群体变得更加密集。监测与巨噬细胞活化相关的细胞因子（主要是白细胞介素（IL）-6 和 IL-10）的表达表明，COVID-19 的病程分为两个阶段，疾病阶段的转换发生在症状出现后的第一周结束时。在初始阶段，免疫系统将严重急性呼吸综合征冠状病毒 2（SARS-CoV-2）识别为非自身，并因此向肺部的巨噬细胞开火以对抗病毒。第一把火可以有效地控制疾病的进展。然而，一个训练有素的免疫能力系统会在更长的时间内保持巨噬细胞的火力。它在于组织驻留巨噬细胞（尤其是肺泡巨噬细胞）中的免疫记忆，这使得一个训练有素的免疫系统比一个未训练的免疫系统更容易受到 COVID-19 的恐惧。通过这种方式，训练有素的免疫能力系统会出现故障，导致肺部迅速衰竭。年轻人群（包括新生儿和儿童）比老年人群对 COVID-19 的易感性较低的事实反映出，未经过充分训练的免疫系统的自然亲和力将成为对抗 COVID-19 的标准，而训练有素的免疫系统对快速激活免疫反应的更高亲和力可能会导致故障——肺部衰竭。
