Programme Hospitalier Recherche Clinique, Institut Pasteur, Inserm, French Public Health Agency.

Natural killer (NK) cells are affected by infection with human cytomegalovirus (HCMV) manifested by increased expression of the HLA-E binding activating receptor NKG2C. We here show that HCMV seropositivity was associated with a profound expansion of NKG2C killer cell immunoglobulin-like receptors (KIRs) specific for self-HLA class I molecules, with predominant usage of KIR2DL2/3. KIR engagement dampened NKG2C-mediated activation suggesting that such biased expression of self-specific KIRs may preserve self-tolerance and limit immune-pathology during viral infection. Together, these findings shed new light on how the human NK-cell compartment adjusts to HCMV infection resulting in clonal expansion and differentiation of educated and polyfunctional NK cells. IntroductionNatural killer (NK) cells have the ability to kill targets without prior sensitization and their involvement in antiviral and antitumor immunity is well established [1,2]. Recent studies have demonstrated a high degree of functional heterogeneity in the NK-cell compartment attributable to a vast network of inhibitory or activating receptors that allow these cells to recognize target cells [3,4]. Killer cell immunoglobulin-like receptors (KIR) and CD94/NKG2 heterodimers are two major types of HLA class I binding receptors that regulate NK cell function [5,6]. Both these receptor-families exist in activating and inhibitory forms and contribute to the functional education of human NK cells by interactions with their cognate ligands [7], whereas KIR are expressed in a stochastic manner with a variegated distribution in the NK cell population [8,9], NKG2A is expressed on all CD56bright NK cells and disappears gradually during differentiation of CD56 dim NK cells [10,11]. NKG2C and NKG2A are covalently associated with CD94 [12]. Both NKG2A and NKG2C specifically interact with the non-classical MHC class-Ib molecule HLA-E, which is expressed at low levels on almost all nucleated cells, and presents peptides derived from signal sequences of other HLA class-I molecules [13]. The affinity of their interaction depends on the sequence of the HLA-E-bound nonamers and is higher for NKG2A than for NKG2C [14,15]. In the CD56 dim subset, NKG2C expression largely excludes NKG2A expression [10,16]. Expression of NKG2C is induced by co-culture with HCMV-infected fibroblasts and correlates with HCMV seropositivity in healthy donors [16,17]. Recently, NKG2C 1 NK cells were shown to expand during HIV and hantavirus infections in HCMV-seropositive patients, suggesting that HCMV may prime the NK-cell compartment for specific expansion of the NKG2C 1 subset upon additional viral encounters [18,19]. Two recent papers have demonstrated increased expression of NKG2C on NK cells in patients with chronic HBV and HCV infection [20,21]. Therefore, we choose this clinical setting to perform an in-depth characterization of the NKG2C 1 NK-cell subset. We show that NKG2C 1 CD56 dim NK cells are terminally differentiated, highly polyfunctional and display a clonal expression of inhib...

Anti-CD20 monoclonal antibodies are widely used for the treatment of hematological malignancies or autoimmune disease but may be responsible for a secondary humoral deficiency. In the context of COVID-19 infection, this may prevent the elicitation of a specific SARS-CoV-2-antibody response. We report a series of 17 consecutive patients with profound B-cell lymphopenia and prolonged COVID-19 symptoms, negative IgG-IgM SARS-CoV-2 serology and a positive RNAemia measured by digital PCR who were treated with four units of COVID-19 convalescent plasma. Within 48 hours following transfusion, all patients except one experienced an amelioration of their clinical symptoms. The inflammatory syndrome abated within a week. Only one patient who needed mechanical ventilation for severe COVID-19 disease died of bacterial pneumonia. SARS-CoV-2 RNAemia decreased to below the sensitivity threshold in 9 out of 9 evaluated patients. Analysis of virus-specific T-cell responses using T-cell enzyme linked immunoSpot (ELISPOT) assay was analyzed before convalescent plasma transfusion in 3 patients. All showed a conserved SARS-CoV-2 T-cell response and poor cross-response to other coronaviruses. No adverse event was reported. In COVID-19 patients unable to mount a specific humoral response to SARS-CoV-2, convalescent plasma with anti-SARS-CoV-2 antibodies appears to be a very promising approach in the context of protracted COVID-19 symptoms.

Background The antiviral efficacy of remdesivir against SARS-CoV-2 is still controversial. We aimed to evaluate the clinical efficacy of remdesivir plus standard of care compared with standard of care alone in patients admitted to hospital with COVID-19, with indication of oxygen or ventilator support. Methods DisCoVeRy was a phase 3, open-label, adaptive, multicentre, randomised, controlled trial conducted in 48 sites in Europe (France, Belgium, Austria, Portugal, Luxembourg). Adult patients (aged ≥18 years) admitted to hospital with laboratory-confirmed SARS-CoV-2 infection and illness of any duration were eligible if they had clinical evidence of hypoxaemic pneumonia, or required oxygen supplementation. Exclusion criteria included elevated liver enzymes, severe chronic kidney disease, any contraindication to one of the studied treatments or their use in the 29 days before random assignment, or use of ribavirin, as well as pregnancy or breastfeeding. Participants were randomly assigned (1:1:1:1:1) to receive standard of care alone or in combination with remdesivir, lopinavir–ritonavir, lopinavir–ritonavir and interferon beta-1a, or hydroxychloroquine. Randomisation used computer-generated blocks of various sizes; it was stratified on severity of disease at inclusion and on European administrative region. Remdesivir was administered as 200 mg intravenous infusion on day 1, followed by once daily, 1-h infusions of 100 mg up to 9 days, for a total duration of 10 days. It could be stopped after 5 days if the participant was discharged. The primary outcome was the clinical status at day 15 measured by the WHO seven-point ordinal scale, assessed in the intention-to-treat population. Safety was assessed in the modified intention-to-treat population and was one of the secondary outcomes. This trial is registered with the European Clinical Trials Database, EudraCT2020-000936-23, and ClinicalTrials.gov , NCT04315948 . Findings Between March 22, 2020, and Jan 21, 2021, 857 participants were enrolled and randomly assigned to remdesivir plus standard of care (n=429) or standard of care only (n=428). 15 participants were excluded from analysis in the remdesivir group, and ten in the control group. At day 15, the distribution of the WHO ordinal scale was: (1) not hospitalised, no limitations on activities (61 [15%] of 414 in the remdesivir group vs 73 [17%] of 418 in the control group); (2) not hospitalised, limitation on activities (129 [31%] vs 132 [32%]); (3) hospitalised, not requiring supplemental oxygen (50 [12%] vs 29 [7%]); (4) hospitalised, requiring supplemental oxygen (76 [18%] vs 67 [16%]); (5) hospitalised, on non-invasive ventilation or high flow oxygen devices (15 [4%] vs 14 [3%]); (6) hospitalised, on invasive mechanical ventilation or extracorporea...