SARS-CoV-2-reactive T-cell receptors isolated from convalescent COVID-19 patients confer potent T-cell effector function

Both B cells and T cells are involved in an effective immune response to SARS-CoV-2, the disease-causing virus of COVID-19. While B cells—with the indispensable help of CD4⁺ T cells—are essential to generate neutralizing antibodies, T cells on their own have been recognized as another major player in effective anti-SARS-CoV-2 immunity. In this report, we provide insights into the characteristics of individual HLA-A*02:01- and HLA-A*24:02-restricted SARS-CoV-2-reactive TCRs, isolated from convalescent COVID-19 patients. We observed that SARS-CoV-2-reactive T-cell populations were clearly detectable in convalescent samples and that TCRs isolated from these T cell clones were highly functional upon ectopic re-expression. The SARS-CoV-2-reactive TCRs described in this report mediated potent TCR signaling in reporter assays with low nanomolar EC50 values. We further demonstrate that these SARS-CoV-2-reactive TCRs conferred powerful T-cell effector function to primary CD8⁺ T cells as evident by a robust anti-SARS-CoV-2 IFN-γ response and in vitro cytotoxicity. We also provide an example of a long-lasting anti-SARS-CoV-2 memory response by reisolation of one of the retrieved TCRs 5 months after initial sampling. Taken together, these findings contribute to a better understanding of anti-SARS-CoV-2 T-cell immunity and may contribute to paving the way toward immunotherapeutics approaches targeting SARS-CoV-2.     

Donors for SARS-CoV-2 Convalescent Plasma for a Controlled Clinical Trial: Donor Characteristics,Content and Time Course of SARS-CoV-2 Neutralizing Antibodies

BackgroundConvalescent plasma is one of the treatment options for COVID-19 which is currently being investigated in many clinical trials. Understanding of donor and product characteristics is important for optimization of convalescent plasma.MethodsPatients who had recovered from CO­VID-19 were recruited as donors for COVID-19 convalescent plasma (CCP) for a randomized clinical trial of CCP for treatment of severe COVID-19 (CAPSID Trial). Titers of neutralizing antibodies were measured by a plaque-reduction neutralization test (PRNT). Correlation of antibody titers with host factors and evolution of neutralizing antibody titers over time in repeat donors were analysed.ResultsA series of 144 donors (41% females, 59% males; median age 40 years) underwent 319 plasmapheresis procedures providing a median collection volume of 850 mL and a mean number of 2.7 therapeutic units per plasmapheresis. The majority of donors had a mild or moderate course of COVID-19. The titers of neutralizing antibodies varied greatly between CCP donors (from <1:20 to >1:640). Donor factors (gender, age, ABO type, body weight) did not correlate significantly with the titer of neutralizing antibodies. We observed a significant positive correlation of neutralization titers with the number of reported COVID-19 symptoms and with the time from SARS-CoV-2 diagnosis to plasmapheresis. Neutralizing antibody levels were stable or increased over time in 58% of repeat CCP donors. Mean titers of neutralizing antibodies of first donation and last donation of repeat CCP donors did not differ significantly (1:86 at first compared to 1:87 at the last donation). There was a significant correlation of neutralizing antibodies measured by PRNT and anti-SARS-CoV-2 IgG and IgA antibodies which were measured by ELISA. CCP donations with an anti-SARS-CoV-2 IgG antibody content above the 25th percentile were substantially enriched for CCP donations with higher neutralizing antibody levels.ConclusionWe demonstrate the feasibility of collection of a large number of CCP products under a harmonized protocol for a randomized clinical trial. Titers of neutralizing antibodies were stable or increased over time in a subgroup of repeat donors. A history of higher number of COVID-19 symptoms and higher levels of anti-SARS-CoV-2 IgG and IgA antibodies in immunoassays can preselect donations with higher neutralizing capacity.     

Donor treatment with pegylated G-CSF augments the generation of IL-10-producing regulatory T cells and promotes transplantation tolerance

We investigated whether the protection from graft-versus-host disease (GVHD) afforded by donor treatment with granulocyte colony-stimulating factor (G-CSF) could be enhanced by dose escalation. Donor treatment with human G-CSF prevented GVHD in the B6 --> B6D2F1 murine model in a dose-dependent fashion, and murine G-CSF provided equivalent protection from GVHD at 10-fold lower doses. Donor pretreatment with a single dose of pegylated G-CSF (peg-G-CSF) prevented GVHD to a significantly greater extent than standard G-CSF (survival, 75% versus 11%, P <.001). Donor T cells from peg-G-CSF-treated donors failed to proliferate to alloantigen and inhibited the responses of control T cells in an interleukin 10 (IL-10)-dependent fashion in vitro. T cells from peg-G-CSF-treated IL-10(-/-) donors induced lethal GVHD; T cells from peg-G-CSF-treated wild-type (wt) donors promoted long-term survival. Whereas T cells from peg-G-CSF wt donors were able to regulate GVHD induced by T cells from control-treated donors, T cells from G-CSF-treated wt donors and peg-G-CSF-treated IL-10(-/-) donors did not prevent mortality. Thus, peg-G-CSF is markedly superior to standard G-CSF for the prevention of GVHD following allogeneic stem cell transplantation (SCT), due to the generation of IL-10-producing regulatory T cells. These data support prospective clinical trials of peg-G-CSF-mobilized allogeneic blood SCT.     

Met-enkephalin modulates lipid peroxidation and total sialic acid level in CBA mice in age- and sex-dependent manners

Age- and sex-associated differences in lipid peroxidation (LPO), and total sialic acid content (TSA) in response to abuse of drugs have been reported both in humans and experimental animals. However, no data on the influence of gender and age on these parameters have been reported for methionine-enkephalin (MENK). In this study we examined the influence of age and gender on MENK-induced LPO levels in the liver and TSA content in splenocytes of CBA mice. LPO production, which was age- and gender-associated was differentially regulated by MENK at a dose of 10 mg or 2.5 mg/kg body weight. At the higher dose, MENK stimulated LPO production in younger males and females but suppressed only in older male mice. At the lower dose, MENK induced strong suppression in males while being without any effect in females. In TSA levels, the age-associated increase was greater in males and much lower in females, with higher TSA levels in younger (2.5, 4.5 months) and decreased levels in older female mice (9 months) being observed. Contrary to the effect on LPO level, TSA level in MENK-treated mice was suppressed in both sexes but only in young 2.5-month-old mice. These data provide evidence that some immunomodulatory properties of MENK are age- and gender-associated which may be relevant to the potential use of MENK as adjuvant therapy in patients with immunocompromised status.     

Evaluation of metal concentration and antioxidant,antimicrobial, and anticancer potentials of two edible mushrooms Lactarius deliciosus and Macrolepiota procera

This study is designed for the determination of metal concentrations, antioxidant, antimicrobial, and anticancer potential of two edible mushrooms Lactarius deliciosus and Macrolepiota procera. Concentrations of nine metals are determined and all metals are present in the allowable concentrations in the tested mushrooms except Cd in M. procera. Antioxidant activity was evaluated by free radical scavenging and reducing power. M. procera extract had more potent free radical scavenging activity (IC₅₀ = 311.40 μg/mL) than L. deliciosus extract. Moreover, the tested extracts had effective reducing power. The total content of phenol in the extracts was examined using Folin–Ciocalteu reagent and obtained values expressed as pyrocatechol equivalents. Further, the antimicrobial potential was determined with a microdilution method on 15 microorganisms. Among the tested species, extract of L. deliciosus showed a better antimicrobial activity with minimum inhibitory concentration values ranging from 2.5 mg/mL to 20 mg/mL. Finally, the cytotoxic activity was tested using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide method on human epithelial carcinoma HeLa cells, human lung carcinoma A549 cells, and human colon carcinoma LS174 cells. Extract of both mushrooms expressed similar cytotoxic activity with IC₅₀ values ranging from 19.01 μg/mL to 80.27 μg/mL.