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Updated: Sep 30, 2025

Author Spotlight: Advancing Immune Monitoring in Critical Care Patients Using Whole Blood Assays
Published on: September 20, 2024
Acute phase of COVID-19 is associated with elevated plasmablasts in the blood
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 specific IgA and IgG antibodies were analyzed using a flow cytometry and immunoassays, respectively.
Results:
Circulating plasmablasts and memory B-lymphocytes were significantly elevated and regulatory B-lymphocytes significantly decreased in the patients in comparison with 11 age- and sex-matched SARS-CoV-2 seronegative healthy adults. Next, circulating plasmablasts correlated negatively with the levels of SARS-CoV-2 specific IgG antibodies, which were detectable in 9 out of 15 tested patients. In addition, SARS-CoV-2 specific 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 significant changes of phenotypes of circulating B-lymphocytes and elevated circulating plasmablasts correlate with decreased SARS-CoV-2-specific IgG antibodies (Tab. 2, Fig. 3, Ref. 14).
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