Circulating antibody-secreting cells are present in the peripheral blood of healthy individuals reflecting the continued activity of the humoral immune system. Antibody-secreting cells typically... Show moreCirculating antibody-secreting cells are present in the peripheral blood of healthy individuals reflecting the continued activity of the humoral immune system. Antibody-secreting cells typically express CD27. Here we describe and characterize a small population of antibody-secreting class switched CD19+CD43+ B cells that lack expression of CD27 in the peripheral blood of healthy subjects. In this study, we characterized CD27-CD43+ cells. We demonstrate that class-switched CD27-CD43+ B cells possess characteristics of conventional plasmablasts as they spontaneously secrete antibodies, are morphologically similar to antibody-secreting cells, show downregulation of B cell differentiation markers, and have a gene expression profile related to conventional plasmablasts. Despite these similarities, we observed differences in IgA and IgG subclass distribution, expression of homing markers, replication history, frequency of somatic hypermutation, immunoglobulin repertoire, gene expression related to Toll-like receptors, cytokines, and cytokine receptors, and antibody response to vaccination. Their frequency is altered in immune-mediated disorders. Conclusionwe characterized CD27-CD43+ cells as antibody-secreting cells with differences in function and homing potential as compared to conventional CD27+ antibody-secreting cells. Show less
Spanjaard, A.; Stratigopoulou, M.; Groot, D. de; Aslam, M.; Berk, P.C.M. van den; Stappenbelt, C.; ... ; Jacobs, H. 2023
The development and differentiation of B cells is intimately linked to cell proliferation and the generation of diverse immunoglobulin gene (Ig) repertoires. The ubiquitin E3 ligase HUWE1 controls... Show moreThe development and differentiation of B cells is intimately linked to cell proliferation and the generation of diverse immunoglobulin gene (Ig) repertoires. The ubiquitin E3 ligase HUWE1 controls proliferation, DNA damage responses, and DNA repair, including the base excision repair (BER) pathway. These processes are of crucial importance for B-cell development in the bone marrow, and the germinal center (GC) response, which results in the clonal expansion and differentiation of B cells expressing high affinity immunoglobulins. Here, we re-examined the role of HUWE1 in B-cell proliferation and Ig gene diversification, focusing on its involvement in somatic hypermutation (SHM) and class switch recombination (CSR). B-cell-specific deletion of Huwe1 resulted in impaired development, differentiation and maturation of B cells in the bone marrow and peripheral lymphoid organs. HUWE1 deficiency diminished SHM and CSR by impairing B-cell proliferation and AID expression upon activation in vitro and in vivo, and was unrelated to the HUWE1-dependent regulation of the BER pathway. Interestingly, we found that HUWE1-deficient B cells showed increased mRNA expression of Myc target genes upon in vitro activation despite diminished proliferation. Our results confirm that the E3 ligase HUWE1 is an important contributor in coordinating the rapid transition of antigen naive, resting B cells into antigen-activated B cells and regulates mutagenic processes in B cells by controlling AID expression and the post-transcriptional output of Myc target genes. Show less
Koers, J.; Pollastro, S.; Tol, S.; Niewold, I.T.G.; Schouwenburg, P.A. van; Vries, N. de; Rispens, T. 2022
In past years ex vivo and in vivo experimental approaches involving human naive B cells have proven fundamental for elucidation of mechanisms promoting B cell differentiation in both health and... Show moreIn past years ex vivo and in vivo experimental approaches involving human naive B cells have proven fundamental for elucidation of mechanisms promoting B cell differentiation in both health and disease. For such studies, it is paramount that isolation strategies yield a population of bona fide naive B cells, i.e., B cells that are phenotypically and functionally naive, clonally non-expanded, and have non-mutated BCR variable regions. In this study different combinations of common as well as recently identified B cell markers were compared to isolate naive B cells from human peripheral blood. High-throughput BCR sequencing was performed to analyze levels of somatic hypermutation and clonal expansion. Additionally, contamination from mature mutated B cells intrinsic to each cell-sorting strategy was evaluated and how this impacts the purity of obtained populations. Our results show that current naive B cell isolation strategies harbor contamination from non-naive B cells, and use of CD27-IgD(+) is adequate but can be improved by including markers for CD45RB glycosylation and IgM. The finetuning of naive B cell classification provided herein will harmonize research lines using naive B cells, and will improve B cell profiling during health and disease, e.g. during diagnosis, treatment, and vaccination strategies. Show less
IJspeert, H.; Schouwenburg, P.A. van; Pico-Knijnenburg, I.; Loeffen, J.; Brugieres, L.; Driessen, G.J.; ... ; Burg, M. van der 2019
