Coronavirus disease 2019 (COVID-19), an acute respiratory infection, is largely associated with dysregulation and impairment of the immune system. This study investigated how the immune system changes were related to disease severity in COVID-19 patients. The frequencies of different immune cells and levels of pro- and anti-inflammatory cytokines in whole blood of participants were determined by flow cytometry and enzyme-linked immunosorbent assay, respectively. The values of other inflammatory agents were also studied. In the late recovery stage, unlike CD56^high CD16^+/− NK cells and monocytes, CD56^low CD16⁺ NK cell numbers were increased (P < 0.0001–0.05). Th1, Th2, and Th17 cell percentages were significantly lower in patients than healthy control (P < 0.0001–0.05), while their frequencies were increased following disease recovery (P < 0.0001–0.05). The numbers of Tregs, activated CD4+ T cells, and exhausted CD8+ T cells were significantly decreased during a recovery (P < 0.0001–0.05). No significant change was observed in exhausted CD4+ T cell number during a recovery (P > 0.05). B cell showed an increased percentage in patients compared to healthy subjects (P < 0.0001–0.05), whereas its number was reduced following recovery (P < 0.0001–0.05). IL-1α, IL-1β, IL-6, TNF-α, and IL-10 levels were significantly decreased in the late recovery stage (P < 0.0001–0.05). However, TGF-β1 level was not significantly changed during the recovery (P > 0.05). Lymphocyte numbers in patients were significantly decreased (P < 0.001), unlike ESR value (P < 0.001). Lymphocyte number was negatively correlated to ESR value and Th2 number (P < 0.05), while its association with monocyte was significantly positive at the first day of recovery (P < 0.05). The immune system changes during the disease recovery to improve and regulate immune responses and thereby may associate with the reduction in disease severity.

2019 年冠状病毒病 (COVID-19) 是一种急性呼吸道感染，很大程度上与免疫系统失调和受损有关。本研究调查了 COVID-19 患者的免疫系统变化与疾病严重程度之间的关系。分别通过流式细胞术和酶联免疫吸附测定测定参与者全血中不同免疫细胞的频率以及促炎和抗炎细胞因子的水平。还研究了其他炎症因子的值。在恢复后期，与 CD56^高CD16 ^+/- NK 细胞和单核细胞不同，CD56^低CD16 ⁺ NK 细胞数量增加（ P < 0.0001–0.05）。患者中 Th1、Th2 和 Th17 细胞百分比显着低于健康对照（ P < 0.0001–0.05），而其频率在疾病恢复后增加（ P < 0.0001–0.05）。在恢复过程中，Tregs、激活的 CD4+ T 细胞和耗尽的 CD8+ T 细胞的数量显着减少 ( P < 0.0001–0.05)。恢复期间耗尽的 CD4+ T 细胞数量未观察到显着变化（ P > 0.05）。与健康受试者相比，患者的 B 细胞百分比有所增加（ P < 0.0001–0.05），而其数量在恢复后减少（ P < 0.0001–0.05）。 IL-1α、IL-1β、IL-6、TNF-α和IL-10水平在恢复后期显着降低（ P < 0.0001–0.05）。恢复期间TGF-β1水平无明显变化（ P >0.05）。与ESR值不同( P <0.001)，患者淋巴细胞数量显着减少( P <0.001)。 恢复第1天淋巴细胞数与ESR值、Th2数呈负相关（ P <0.05），与单核细胞呈显着正相关（ P <0.05）。免疫系统在疾病恢复过程中发生变化，以改善和调节免疫反应，从而可能与疾病严重程度的减轻有关。