Tu111 - Severity of SARS-CoV-2 Infection is Linked to Double Negative (CD27- IgD-) B Cell Subsets Numbers

Background: The role of B cells in COVID‐19, beyond the production of specific antibodies against SARS-CoV-2, is still not well understood. Here, we describe the novel landscape of circulating Double Negative (DN) CD27- IgD- B cells in COVID‐19 patients, representing a group of atypical and neglected subpopulations of this cell lineage.

Methods: Using multiparametric flow cytometry, we determined DN B cell subsets (frequencies and absolute numbers) from a cohort of 91 COVID-19 patients, correlated those with cytokines, clinical and laboratory parameters, and segregated them by principal components analysis.

Results: We detected significant increments in the DN2 and DN3 B cell subsets, while we found a relevant decrease in the DN1 B cell subpopulation, according to disease severity and patient outcomes. These DN cell numbers also appeared to correlate with pro or anti-inflammatory signatures respectively and contributed to the segregation of the patients into disease severity groups.

Conclusion: This study provides insights into DN B cell subsets' potential role in immune responses against SARS‐CoV‐2, particularly linked to the severity of COVID‐19.

Supported by CONACyT A3-S-36875 and UNAM-DGAPA-PAPIIT IN212122.