The spectrum of coronavirus disease 2019 (COVID-19) severity, related to cellular immune functions, has not been fully clarified yet. Therefore, this study aimed to investigate the alteration of peripheral blood cells in patients with COVID-19. The flow cytometric characterization of immune cell subset was performed on 69 COVID-19 patients and 21 healthy controls. These data were evaluated based on the disease severity. A total of 69 patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) were classified as asymptomatic infection (n = 14), nonsevere (n = 39), and severe (n = 16) groups. Decreased lymphocytes and increased CD14 + 4- monocytes are found in patients with severe COVID-19. Decreased CD4 expression level was observed in the monocytes of patients with severe COVID-19. The total lymphocytes, B and T lymphocytes, CD4+ cells and CD8+ cells, and natural killer (NK) and natural killer T (NKT) cells were found to be decreased in patients with severe COVID-19. The CD4+/CD8+ ratio was not significantly different between patients with COVID-19 and healthy controls. The percentage of activated T cells (CD3+HLA-DR+) and B cells (CD19+CD38+) was lower in patients with severe COVID-19. Age and CD4− monocytes were independent predictors of disease severity. The SARS-CoV-2 infection may affect lymphocyte subsets, resulting in decreased T and B cells, monocytes, and NK and NKT cells. Decreased CD4 expression level by monocytes was significantly correlated with disease severity. Further studies on the host immune response to SARS-CoV-2 infection are necessary to predict the disease severity and protect against the virus.

中文翻译：

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重症 COVID-19 患者淋巴细胞亚群改变和单核细胞 CD4 表达降低

与细胞免疫功能相关的 2019 年冠状病毒病 (COVID-19) 严重程度范围尚未完全阐明。因此，本研究旨在调查 COVID-19 患者外周血细胞的变化。对 69 名 COVID-19 患者和 21 名健康对照者进行了免疫细胞亚群的流式细胞术表征。这些数据是根据疾病严重程度评估的。共有 69 名感染严重急性呼吸综合征冠状病毒 2（SARS-CoV-2）的患者被分类为无症状感染（n  = 14）、非严重（n  = 39）和严重（n = 16) 组。在重症 COVID-19 患者中发现淋巴细胞减少和 CD14 + 4- 单核细胞增加。在重症 COVID-19 患者的单核细胞中观察到 CD4 表达水平降低。发现重症 COVID-19 患者的总淋巴细胞、B 和 T 淋巴细胞、CD4+ 细胞和 CD8+ 细胞以及自然杀伤 (NK) 和自然杀伤 T (NKT) 细胞减少。CD4+/CD8+ 比率在 COVID-19 患者和健康对照组之间没有显着差异。在重症 COVID-19 患者中，活化 T 细胞（CD3+HLA-DR+）和 B 细胞（CD19+CD38+）的百分比较低。年龄和 CD4- 单核细胞是疾病严重程度的独立预测因子。SARS-CoV-2 感染可能会影响淋巴细胞亚群，导致 T 和 B 细胞、单核细胞以及 NK 和 NKT 细胞减少。单核细胞降低的 CD4 表达水平与疾病严重程度显着相关。有必要进一步研究宿主对 SARS-CoV-2 感染的免疫反应，以预测疾病的严重程度并预防病毒。