Acute phase of COVID-19 is associated with elevated plasmablasts in the blood

Abstract

OBJECTIVES: The study was aimed at the characterization of humoral immunity in acute SARS-CoV-2 infection. BACKGROUND: Humoral immunity plays a central role in the protection from infection due to SARS-CoV-2, causative agent of coronavirus diseases 2019 (COVID-19). PATIENTS AND METHODS: In 24 adult patients hospitalized with COVID-19, the functional subsets of circulating B-lymphocytes and SARS-CoV-2 specifi c IgA and IgG antibodies were analyzed using a fl ow cytometry and immunoassays, respectively. RESULTS: Circulating plasmablasts and memory B-lymphocytes were signifi cantly elevated and regulatory B-lymphocytes signifi cantly decreased in the patients in comparison with 11 age and sex-matched SARSCoV-2 seronegative healthy adults. Next, circulating plasmablasts correlated negatively with the levels of SARS-CoV-2 specifi c IgG antibodies, which were detectable in 9 out of 15 tested patients. In addition, SARSCoV-2 specifi c IgA antibodies were detectable in 13 of 15 tested patients and did not demonstrate correlation with any B-lymphocyte subset. CONCLUSION: Severe course of COVID-19 is associated with signifi cant changes of phenotypes of circulating B-lymphocytes and elevated circulating plasmablasts correlate with decreased SARS-CoV-2-specifi c IgG antibodies (Tab. 2, Fig. 3, Ref. 14). Text in PDF www.elis.sk