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Front Immunol ; 12: 774491, 2021.
Article in English | MEDLINE | ID: covidwho-1648672


Common human coronaviruses have been circulating undiagnosed worldwide. These common human coronaviruses share partial sequence homology with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2); therefore, T cells specific to human coronaviruses are also cross-reactive with SARS-CoV-2 antigens. Herein, we defined CD4+ T cell responses that were cross-reactive with SARS-CoV-2 antigens in blood collected in 2016-2018 from healthy donors at the single allele level using artificial antigen-presenting cells (aAPC) expressing a single HLA class II allotype. We assessed the allotype-restricted responses in the 42 individuals using the aAPCs matched 22 HLA-DR alleles, 19 HLA-DQ alleles, and 13 HLA-DP alleles. The response restricted by the HLA-DR locus showed the highest magnitude, and that by HLA-DP locus was higher than that by HLA-DQ locus. Since two alleles of HLA-DR, -DQ, and -DP loci are expressed co-dominantly in an individual, six different HLA class II allotypes can be used to the cross-reactive T cell response. Of the 16 individuals who showed a dominant T cell response, five, one, and ten showed a dominant response by a single allotype of HLA-DR, -DQ, and -DP, respectively. The single allotype-restricted T cells responded to only one antigen in the five individuals and all the spike, membrane, and nucleocapsid proteins in the six individuals. In individuals heterozygous for the HLA-DPA and HLA-DPB loci, four combinations of HLA-DP can be expressed, but only one combination showed a dominant response. These findings demonstrate that cross-reactive T cells to SARS-CoV-2 respond with single-allotype dominance.

Alleles , Antigens, Viral/immunology , CD4-Positive T-Lymphocytes/immunology , COVID-19/immunology , Genes, MHC Class II , HLA-D Antigens/genetics , SARS-CoV-2/immunology , Adult , Antigen-Presenting Cells/immunology , Blood Donors , COVID-19/virology , Cells, Cultured , Cross Reactions , Enzyme-Linked Immunospot Assay/methods , Female , HLA-D Antigens/immunology , Healthy Volunteers , Humans , Immunoglobulin Allotypes/immunology , Male , Young Adult
Front Immunol ; 12: 734689, 2021.
Article in English | MEDLINE | ID: covidwho-1354868


The response to anti-SARS-Cov-2 preventive vaccine shows high interpersonal variability at short and medium term. One of the explanations might be the individual HLA allelic variants. Indeed, B cell response is stimulated and sustained by CD4+ T helper cells activated by antigens presented by HLA-class II alleles on antigen-presenting cells (APCs). The impact of the number of antigens binding to HLA class-II alleles on the antibody response to the COVID vaccine has been assessed in a cohort of 56 healthcare workers who received the full schedule of the Pfizer-BioNTech BNT162b2 vaccine. Such vaccine is based on the entire spike protein of the SARS-CoV-2. Ab titers have been evaluated 2 weeks after the first dose as well as 2 weeks and 4 months after the boosting dose. HLA-DRB1 and DBQ1 for each of the vaccinees have been assessed, and strong binders have been predicted. The analysis showed no significant correlation between the short-medium-term Ab titers and the number of strong binders (SB) for each individual. These results indicate that levels of Ab response to the spike glycoprotein is not dependent on HLA class II allele, suggesting an equivalent efficacy at global level of the currently used vaccines. Furthermore, the pattern of persistence in Ab titer does not correlate with specific alleles or with the number of SBs.

Antibodies, Viral/blood , COVID-19 Vaccines/immunology , HLA-D Antigens/immunology , SARS-CoV-2/immunology , Antibodies, Viral/immunology , Antibody Affinity/immunology , Antigens, Viral/immunology , COVID-19/prevention & control , Humans , Spike Glycoprotein, Coronavirus/immunology
Nat Metab ; 2(10): 1021-1024, 2020 10.
Article in English | MEDLINE | ID: covidwho-744385


Here we report a case where the manifestations of insulin-dependent diabetes occurred following SARS-CoV-2 infection in a young individual in the absence of autoantibodies typical for type 1 diabetes mellitus. Specifically, a 19-year-old white male presented at our emergency department with diabetic ketoacidosis, C-peptide level of 0.62 µg l-1, blood glucose concentration of 30.6 mmol l-1 (552 mg dl-1) and haemoglobin A1c of 16.8%. The patient´s case history revealed probable COVID-19 infection 5-7 weeks before admission, based on a positive test for antibodies against SARS-CoV-2 proteins as determined by enzyme-linked immunosorbent assay. Interestingly, the patient carried a human leukocyte antigen genotype (HLA DR1-DR3-DQ2) considered to provide only a slightly elevated risk of developing autoimmune type 1 diabetes mellitus. However, as noted, no serum autoantibodies were observed against islet cells, glutamic acid decarboxylase, tyrosine phosphatase, insulin and zinc-transporter 8. Although our report cannot fully establish causality between COVID-19 and the development of diabetes in this patient, considering that SARS-CoV-2 entry receptors, including angiotensin-converting enzyme 2, are expressed on pancreatic ß-cells and, given the circumstances of this case, we suggest that SARS-CoV-2 infection, or COVID-19, might negatively affect pancreatic function, perhaps through direct cytolytic effects of the virus on ß-cells.

Betacoronavirus , Coronavirus Infections/complications , Coronavirus Infections/diagnosis , Diabetes Mellitus, Type 1/complications , Pneumonia, Viral/complications , Pneumonia, Viral/diagnosis , Antibodies, Viral/blood , Antibodies, Viral/immunology , Autoantibodies/blood , Autoantibodies/immunology , Betacoronavirus/immunology , Biomarkers , COVID-19 , Coronavirus Infections/immunology , Diabetes Mellitus, Type 1/diagnosis , Diabetes Mellitus, Type 1/genetics , Diabetes Mellitus, Type 1/immunology , HLA-D Antigens/genetics , HLA-D Antigens/immunology , Humans , Immunoglobulin M/immunology , Insulin/metabolism , Insulin-Secreting Cells/immunology , Insulin-Secreting Cells/metabolism , Islets of Langerhans/immunology , Male , Pandemics , Pneumonia, Viral/immunology , SARS-CoV-2 , Young Adult