Cellular and humoral immunity to SARS-CoV-2 is critical to control primary infection and correlates with severity of disease. The role of SARS-CoV-2-specific T cell immunity, its relationship to antibodies, and pre-existing immunity against endemic coronaviruses (huCoV), which has been hypothesized to be protective, were investigated in 82 healthy donors (HDs), 204 recovered (RCs), and 92 active COVID-19 patients (ACs). ACs had high amounts of anti-SARS-CoV-2 nucleocapsid and spike IgG but lymphopenia and overall reduced antiviral T cell responses due to the inflammatory milieu, expression of inhibitory molecules (PD-1, Tim-3) as well as effector caspase-3, -7, and -8 activity in T cells. SARS-CoV-2-specific T cell immunity conferred by polyfunctional, mainly interferon-γ-secreting CD4⁺ T cells remained stable throughout convalescence, whereas humoral responses declined. Immune responses toward huCoV in RCs with mild disease and strong cellular SARS-CoV-2 T cell reactivity imply a protective role of pre-existing immunity against huCoV.

对 SARS-CoV-2 的细胞和体液免疫对于控制原发感染至关重要，并与疾病的严重程度相关。SARS-CoV-2 特异性 T 细胞免疫的作用、它与抗体的关系，以及针对地方性冠状病毒 (huCoV) 的预先存在的免疫力（假设具有保护作用）在 82 名健康供体 (HD) 中进行了研究，204康复 (RC) 和 92 名活跃的 COVID-19 患者 (AC)。AC 具有大量抗 SARS-CoV-2 核衣壳和刺突 IgG，但由于炎症环境、抑制分子（PD-1、Tim-3）的表达以及效应子半胱天冬酶，导致淋巴细胞减少和总体抗病毒 T 细胞反应降低T 细胞中的 3、-7 和 -8 活性。多功能的 SARS-CoV-2 特异性 T 细胞免疫，主要是分泌干扰素-γ 的 CD4 ⁺T 细胞在整个恢复期保持稳定，而体液反应下降。在患有轻度疾病和强细胞 SARS-CoV-2 T 细胞反应性的 RC 中，对 huCoV 的免疫反应意味着预先存在的针对 huCoV 的免疫力具有保护作用。