Expansion of SARS-CoV-2-specific Antibody-secreting Cells and Generation of Neutralizing Antibodies in Hospitalized COVID-19 Patients

TLDR: This study observed a significant expansion of SARS-CoV-2 nucleocapsid protein-specific ASCs in all twenty COVID-19 patients using a multicolor FluoroSpot assay, and found that Sars-Cov-2-specific IgA, IgG and IgM antibody levels positively correlated with SARS -CoV -2-neutralizing antibody titers.

Abstract: COVID-19, caused by SARS-CoV-2, emerged in late 2019 and has since become a global pandemic. Pathogen-specific antibodies are typically a major predictor of protective immunity, yet B cell and antibody responses during COVID-19 are not fully understood. Here, we analyzed antibody-secreting cell (ASC) and antibody responses in twenty hospitalized COVID-19 patients. We observed a significant expansion of SARS-CoV-2 nucleocapsid protein-specific ASCs in all twenty COVID-19 patients using a multicolor FluoroSpot assay. Out of the 20 patients, 16 had developed SARS-CoV-2-neutralizing antibodies by the time of sampling. Additionally, we found that SARS-CoV-2-specific IgA, IgG and IgM antibody levels positively correlated with SARS-CoV-2-neutralizing antibody titers. This study constitutes a detailed description of B cell and antibody responses to SARS-CoV-2 in COVID-19, and provides tools to study immune responses to SARS-CoV-2 infection and vaccination.