SARS-CoV-2 infection causes immunodeficiency in recovered patients by downregulating CD19 expression in B cells via enhancing B-cell metabolism

The study, titled “SARS-CoV-2 infection causes immunodeficiency in recovered patients by downregulating CD19 expression in B cells via enhancing B-cell metabolism” explores the impact of SARS-CoV-2 infection on the immune system, particularly focusing on B cells in recovered COVID-19 patients. The researchers aimed to understand how the virus affects the immune response and B-cell function post-recovery.

Here is a detailed summary:


  • Context: The study begins by addressing the known immune disruption caused by SARS-CoV-2, including a cytokine storm leading to severe complications like ARDS. The role of B cells in this context, however, remained unclear.
  • Objective: The primary goal was to investigate how SARS-CoV-2 infection alters the immune phenotype and function of B cells in recovered COVID-19 patients.


  • Subjects: The study involved 15 recovered COVID-19 patients and compared their B cells with those from healthy controls.
  • Techniques: Various techniques like flow cytometry, Western blotting, confocal microscopy, and transcriptome and metabolome analysis were used to assess changes in B cells and serum metabolites.

Key Findings

  1. Altered B-Cell Phenotype and Function:
    • The study found that recovered COVID-19 patients had a significant increase in plasma blast cells (PBC) and a decrease in unswitched memory B cells compared to healthy controls.
    • CD19 expression was notably reduced in B-cell subsets of recovered patients, indicating altered immune function.
  2. Disruption in BCR Signaling and Metabolism:
    • CD19, a critical regulator of B-cell receptor (BCR) signaling, showed reduced expression in recovered patients.
    • This was linked to dysregulated cell metabolism and increased production of reactive oxygen species (ROS).
  3. Serum Metabolite Changes:
    • The serum from recovered patients showed significant changes in metabolites, including reduced levels of certain amino acids.
    • These changes could potentially influence B-cell signaling and function.
  4. Transcriptome Analysis:
    • A significant alteration in the expression of genes related to metabolism was observed, highlighting the metabolic shift in B cells post-infection.
  5. Impact on Early B-Cell Activation:
    • The study observed that early activation of B cells was inhibited in recovered patients, affecting BCR signaling.


  • Immunodeficiency in Recovered Patients: The study concludes that SARS-CoV-2 infection leads to immunodeficiency in recovered patients by downregulating CD19 expression in B cells. This downregulation is attributed to enhanced B-cell metabolism and increased ROS production.
  • Clinical Implications: Understanding these changes opens potential avenues for targeting metabolic pathways in COVID-19 treatment and possibly preventing reinfection in recovered patients.


This research provides critical insights into the long-term effects of COVID-19 on the immune system, especially concerning B-cell functionality and immune response post-recovery. It highlights the importance of monitoring recovered patients for potential immunodeficiencies and considering metabolic interventions in their ongoing care.

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