Noncanonical B Cells: Characteristics of Uncharacteristic B Cells

Abstract

B lymphocytes were originally described as a cell type uniquely capable of secreting Abs. The importance of T cell help in Ab production was revealed soon afterward. Following these seminal findings, investigators made great strides in delineating steps in the conventional pathway that B cells follow to produce high-affinity Abs. These studies revealed generalized, or canonical, features of B cells that include their developmental origin and paths to maturation, activation, and differentiation into Ab-producing and memory cells. However, along the way, examples of nonconventional B cell populations with unique origins, age-dependent development, tissue localization, and effector functions have been revealed. In this brief review, features of B-1a, B-1b, marginal zone, regulatory, killer, NK-like, age-associated, and atypical B cells are discussed. Emerging work on these noncanonical B cells and functions, along with the study of their significance for human health and disease, represents an exciting frontier in B cell biology.

Identification and characterisation ofPlanococcus citri cis- andtrans-isoprenyl diphosphate synthase genes, supported by short- and long-read transcriptome data

“…The consolidated transcriptome set was mapped to the Pcitri .v1 genome using STARlong v2.7.5c (Dobin et al, 2013) and mapped transcripts were matched with the gene models and scaffolds using matchAnnot (Skelly, 2015; version 20150611.02). Transcripts were also subjected to ORF prediction and translation using Transdecoder v5.5.0 (Haas, 2023), followed by the annotation of the predicted protein sequences with PFAM and InterPro (IPR) IDs using InterProScan v5.56-89.0 (Jones et al, 2014). The longest ORFs were further used for taxonomic classification using mmseq2 taxonomy tool (Mirdita et al, 2021), querying against the non-redundant NCBI protein database (downloaded on 19.07.2022).…”

Intruders or protectors – the multifaceted role of B cells in CNS disorders

“…The observed reduction in B cell numbers may also be associated with the decrease in B cell precursors caused by reduced surrogate L chains in senescent B cell precursors and compromised pre-BCR checkpoints ( Alter-Wolf et al, 2009a , b ). Notably, age-associated changes in immune populations have been correlated with autoimmune diseases, especially through the emergence of atypical B cells, termed ABCs ( Haas, 2023 ). ABCs are characterized by T-bet and CD11c expression and have been shown to exhibit selective amplified responses to stimulation via TLR7/TLR9 but not TLR2/TLR4 ( Hao et al, 2011 ; Rubtsov et al, 2011 ).…”

“…Originating from progenitor cells in the fetal liver and the adult bone marrow, B lymphocytes undergo multiple stages of development, and complex maturation in the peripheral lymphoid organs ( LeBien and Tedder, 2008 ; Maddaly et al, 2010 ). The broad diversity of B cell populations has increasingly been recognized, and while conventional follicular B cells are the predominant recirculating B cell population and the main source of antibody production, a variety of non-canonical B cell subsets have been described ( Haas, 2023 ) ( Figure 2 ). These include B-1 cells, an innate population of B cells found mostly in serosal cavities; marginal zone (MZ) B cells, innate B cells which can respond rapidly, in a T-cell independent manner, to blood-borne and commensal pathogens through the production of IgM and class-switched immunoglobulin G (IgG) and IgA antibodies; regulatory B cells (Bregs), a broad spectrum of B cells characterized by their ability to produce immunosuppressive cytokines; killer B cells, which express high levels of Fas-ligand and can induce apoptosis in T cells and other cell types; and age-associated B cells (ABCs), atypical memory B cell populations, characterized by expression of T-bet and CD11c, and thought to promote inflammatory responses ( Cerutti et al, 2013 ; Haas, 2023 ).…”

Breg-Mediated Immunoregulation in the Skin

“…The count of diverse subpopulations of regulatory B cells currently exceed ten [ 13 ] and unfortunately, there is no universally accepted specific marker that sets them apart from other B cell subsets. As a result, the term “Breg” is commonly used as a general label, denoting B cells with immunosuppressive potential [ 14 , 15 , 16 ]. Bregs suppress immune responses and promote tissue repair by producing anti-inflammatory cytokines and interacting with other immune cells [ 17 ].…”