Intrinsic properties of germinal center‐derived B cells promote their enhanced class switching to IgE

Abstract

BackgroundResearch on the origins and development of human IgE‐expressing (IgE+) cells is required for understanding the pathogenesis of allergy and asthma. These studies have been thwarted by the rarity of IgE+ cells in vivo and the low frequency of class switch recombination (CSR) to IgE ex vivo. To determine the main source of IgE+ cells, we investigated the relation between the phenotypic composition of tonsil B cells and the CSR to IgE ex vivo.MethodsHuman tonsil B cells were analyzed by flow cytometry (FACS) and cultured with IL‐4 and anti‐CD40 to induce CSR to IgE. Naïve, germinal center (GC), early GC (eGC), and memory tonsil B cells were isolated by FACS, and their capacities for IL‐4 and anti‐CD40 signaling, cell proliferation, and de novo class switching to IgE were analyzed by RT‐PCR and FACS.ResultsB cells from different tonsils exhibited varying capacities for CSR to IgE ex vivo. This was correlated with the percentage of eGC B cells in the tonsil at the outset of the culture. Despite relatively poor cell viability, eGC and GC B‐cell cultures produced the highest yields of IgE+ cells compared to naïve and memory B‐cell cultures. The main factors accounting for this result were the strength of IL‐4R and CD40 signaling and relative rates of cell proliferation.ConclusionsThis study shows that the maturation state of tonsil B cells determines their capacity to undergo class switching to IgE ex vivo, with the GC‐derived B cells yielding the highest percentage of IgE+ cells.

Global gene regulation during activation of immunoglobulin class switching in human B cells

“…PRC1 is a known associative protein of KIF1410, acting together to promote cell division, and all three of these genes have reported mutations and/or clinically significant variation in abundance in various cancers1112. These cytokinesis and proliferation related transcriptional changes may have implications for the efficiency of class switching, as well as the regulation of isotype class1314.…”

miR-29b directly targets activation-induced cytidine deaminase in human B cells and can limit its inappropriate expression in naïve B cells

“…After days in culture, IL-4 and anti-CD40 stimulated B cells transfected with either the miR29b mimic or non-silencing control were similarly viable (cell viability 10.3% + /-2.2 versus 11.2% + /-2.0), although viability was reduced 2.5 fold compared to similarly stimulated un-transfected cells (Ramadani et al, 2015). Intracellular staining of immunoglobulin protein at day 7 reproduced a similar moderate but statistically significant reduction in the percentage of IgE-expressing cells (Fig.…”

“…48 hours) in this system, this is the timepoint at which most AID is functionally active, and thus might affect CSR. When provided with anti-CD40 and IL-4 stimulation, tonsil B cells maintain their IgG expression, with switching to and from IgG being balanced, over the course of 7 days, but significantly increase switching to IgE from negligible to detectable levels, and thus can be tracked via flow cytometry (Ramadani et al, 2015). Assessment of Ig gene expression in B cell cultures by qRT-PCR, days after transfection with a miR-29b mimic, revealed a moderate but reproducible, 30% decrease in IgE mRNA (Fig.…”

Marshallagia marshalli Antigen Strengthens Dendritic Cell Medi-ated T Lymphocyte Regulation on Asthmatic Patients

“…The inflammation caused by asthma is originated from Th2 lymphocytes, which secrete a group of cytokines including IL-5, IL-4, IL-3, IL-13 and GM-CSF (2,9,10). Th2 cytokines are responsible for the regular management of an allergic inflammatory cascade that occurs in asthma, such as changing the class of secretory antibodies from plasma cells to IgE (IL-13 and IL-4), the differentiation of mast cells (IL-3 and IL-4 and IL-13), maturation and survival of eosinophils (IL-3, IL-5 and GM-CSF) and summons of basophils (IL-3 and GM-CSF) (11)(12)(13).…”