Distinguishing naive‐ from memory‐derived human B cells during acute responses

Abstract

Objectives A fundamental question in influenza research is whether antibody titre decline upon successive exposure to variant strains is consequent to recall of cross‐reactive memory B cells that competitively inhibit naive B‐cell responses. In connection, it is not clear whether naive and memory B cells remain phenotypically distinct acutely after activation such that they may be distinguished ex vivo. Methods Here, we first compared the capacity of anti‐Ig and Toll‐like‐receptor (TLR) 7/8 and TLR9 agonists (R848 and CpG) to augment human B‐cell differentiation induced by IL‐21 and sCD40L. The conditions that induced optimal differentiation were then used to compare the post‐activation phenotype of sort‐purified naive and memory B‐cell subsets by FACS and antibody‐secreting cell (ASC) ELISPOT. Results Sort‐purified naive and memory B cells underwent robust plasmablast and ASC formation when stimulated with R848, but not CpG, and co‐cultured with monocytes. This coincided with increased IL‐1β and IL‐6 production when B cells were co‐cultured with monocytes and stimulated with R848, but not CpG. Naive B cells underwent equivalent ASC generation, but exhibited less class‐switch and modulation of CD27, CD38 and CD20 expression than memory B cells after stimulation with R848 and monocytes for 6 days. Conclusion Stimulation with R848, IL‐21 and sCD40L in the presence of monocytes induces robust differentiation and ASC generation from both naive and memory B‐cells. However, naive and memory B cells retain key phenotypic differences after activation that may facilitate ex vivo discrimination and better characterisation of acute responses to variant antigens.

Systemic and intestinal porcine epidemic diarrhea virus-specific antibody response and distribution of antibody-secreting cells in experimentally infected conventional pigs

“…We thus further analyzed the distribution of memory B cells in PEDV-inoculated pigs by examining the level of antibodies produced by MNCs isolated from blood and each tissue following in vitro stimulation. We stimulated isolated MNCs with the TLR7/8 agonist R848, which induces polyclonal memory B-cell expansion and antibody production without a specific antigen [ 37 , 48 – 50 ]. Because B-cell responses can vary depending on the dose and virus proteins used for stimulation [ 32 , 51 ], we hypothesized that in vitro stimulation with R848 may provide a clearer picture of memory B-cell responses to PEDV than stimulation with recombinant proteins or partially purified viruses.…”

R848 Is Involved in the Antibacterial Immune Response of Golden Pompano (Trachinotus ovatus) Through TLR7/8-MyD88-NF-κB-Signaling Pathway

“…Previous studies have shown that R848 induces the activation of CD4 + Th1 cells and CD8 + cytotoxic T lymphocytes ( 8 , 55 ), promotes the proliferation of B cells and inhibits their apoptosis ( 21 , 56 , 57 ). Recently, R848 was demonstrated to enhance human B cell differentiation induced by IL-21 and sCD40L ( 58 ). In mice, R848 augments the proliferation of the bone marrow CD11c + B lymphocyte population ( 59 ).…”

A highly efficient T-cell immunoassay provides assessment of B cell help function of SARS-CoV-2 specific memory CD4+T cells

“…However, B cells survive the ex vivo cultures in the presence of stimulation with synthetic ligands, such as TLR7/8 and TLR9 agonists, which help B cells to activate and differentiate into plasma cells in antigen non-specific manner (den Hartog et al, 2018;Jahnmatz et al, 2013). Also, R848 and CpG augment the non-specific proliferation of the B cells in presence of T cell derived factors, IL-21 and CD40L (Auladell et al, 2019;Franke et al, 2020). Besides, enhanced survival and proliferation of B cells was associated with the accumulated monocytes in the tumor microenvironment (Epron et al, 2012).…”