Critical COVID-19 is associated with distinct leukocyte phenotypes and transcriptome patterns.

Area of Science:

• Immunology
• Virology
• Genomics

Background:

• Prognostic markers for COVID-19 severity and therapeutic targets are needed.
• Innate and adaptive immune responses were studied at protein and transcriptomic levels in COVID-19 patients.

Purpose of the Study:

• To characterize the immune profiles of COVID-19 patients with varying disease severity.
• To identify potential prognostic markers and therapeutic targets.

Main Methods:

• Peripheral blood mononuclear cells (PBMCs) from 31 COVID-19 patients and controls were analyzed using flow cytometry and RNA sequencing.
• Patients were categorized into mild/moderate, severe, or critical disease groups based on WHO guidelines.

Main Results:

• Decreased interleukin 7 receptor alpha chain (CD127) on T cells and reduced monocytic HLA-DR expression were associated with COVID-19 severity.
• Increased T-cell activation/exhaustion markers and elevated monocytic PD-L1/CD142 were observed.
• Critical COVID-19 showed increased plasma B-cell activity and reduced immune response-related transcripts, especially affecting B cells.

Conclusions:

• Critical COVID-19 is characterized by an immune phenotype of activated/exhausted T cells and monocytes, potentially impairing T-cell responses.
• Elevated plasma B-cell activity and reduced immune transcripts in critical cases highlight B cells as potential therapeutic targets.