Receptor Editing Can Lead to Allelic Inclusion and Development of B Cells That Retain Antibodies Reacting with High Avidity Autoantigens (original) (raw)
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Receptor editing: an approach by autoreactive B cells to escape tolerance
Journal of Experimental Medicine, 1993
To determine the fate of anti-DNA antibody-bearing B cells in normal mice, we generated transgenic mice bearing the heavy (H) and light (L) chain genes of a well-characterized anti-double-stranded DNA antibody. This antibody was originally isolated from a diseased MRL/lpr mouse and has characteristics common to spontaneously arising anti-DNA antibodies. Results show that the H/L transgene (tg) immunoglobulin receptor is not expressed by animals bearing both tgs, although single tg animals (H or L) express their transgenes. Young H/L tg animals express few B cells, whereas adult H/L tg animals maintain almost normal B cell numbers. Analysis of the immunoglobulin receptors used by adult B cells shows that all contain the tg H chain in association with endogenous L chains. These B cells transcribe the L tg as well as the rearranged endogenous L chain gene, and loss of endogenous L chain gene transcription results in resurrection of the 3H9 H/L tg product. Examination of the endogenous ...
Receptor editing and genetic variability in human autoreactive B cells
Journal of Experimental Medicine, 2015
The mechanisms by which B cells undergo tolerance, such as receptor editing, clonal deletion, and anergy, have been established in mice. However, corroborating these mechanisms in humans remains challenging. To study how autoreactive human B cells undergo tolerance, we developed a novel humanized mouse model. Mice expressing an anti–human Igκ membrane protein to serve as a ubiquitous neo self-antigen (Ag) were transplanted with a human immune system. By following the fate of self-reactive human κ+ B cells relative to nonautoreactive λ+ cells, we show that tolerance of human B cells occurs at the first site of self-Ag encounter, the bone marrow, via a combination of receptor editing and clonal deletion. Moreover, the amount of available self-Ag and the genetics of the cord blood donor dictate the levels of central tolerance and autoreactive B cells in the periphery. Thus, this model can be useful for studying specific mechanisms of human B cell tolerance and to reveal differences in ...
B Cell Tolerance Checkpoints That Restrict Pathways of Antigen-Driven Differentiation
Journal of Immunology, 2006
Autoreactive B cells can be regulated by deletion, receptor editing, or anergy. Rheumatoid factor (RF)-expressing B lymphocytes in normal mice are not controlled by these mechanisms, but they do not secrete autoantibody and were presumed to ignore self-Ag. Surprisingly, we now find that these B cells are not quiescent, but instead are constitutively and specifically activated by self-Ag. In BALB/c mice, RF B cells form germinal centers (GCs) but few Ab-forming cells (AFCs). In contrast, autoimmune mice that express the autoantigen readily generate RF AFCs. Most interestingly, autoantigen-specific RF GCs in BALB/c mice appear defective. B cells in such GCs neither expand nor are selected as efficiently as equivalent cells in autoimmune mice. Thus, our data establish two novel checkpoints of autoreactive B cell regulation that are engaged only after initial autoreactive B cell activation: one that allows GCs but prevents AFC formation and one that impairs selection in the GC. Both of these checkpoints fail in autoimmunity.
B Cell Tolerance Checkpoints That Restrict Pathways of Antigen-Driven Differentiation 1
2008
Autoreactive B cells can be regulated by deletion, receptor editing, or anergy. Rheumatoid factor (RF)-expressing B lymphocytes in normal mice are not controlled by these mechanisms, but they do not secrete autoantibody and were presumed to ignore self-Ag. Surprisingly, we now find that these B cells are not quiescent, but instead are constitutively and specifically activated by self-Ag. In BALB/c mice, RF B cells form germinal centers (GCs) but few Ab-forming cells (AFCs). In contrast, autoimmune mice that express the autoantigen readily generate RF AFCs. Most interestingly, autoantigen-specific RF GCs in BALB/c mice appear defective. B cells in such GCs neither expand nor are selected as efficiently as equivalent cells in autoimmune mice. Thus, our data establish two novel checkpoints of autoreactive B cell regulation that are engaged only after initial autoreactive B cell activation: one that allows GCs but prevents AFC formation and one that impairs selection in the GC. Both of ...
The Journal of Immunology, 2009
In healthy individuals, a substantial proportion of circulating Abs exhibit polyreactivity and self-reactivity. These Abs are referred to as natural autoantibodies (NAAs). As part of the innate immunity, NAAs play an important role in eliminating pathogens. However, inherent to their poly/autoreactivity is the potential for NAAs to differentiate to high-affinity autoantibodies during an immune response. We recently generated site-directed transgenic mice that express a prototypic NAA, ppc1-5, which binds a variety of self-and non-self-Ags including DNA and phosphocholine. We have shown previously that B cells expressing the ppc1-5 NAA are positively selected during their primary development. In this study, we demonstrate that following immunization with the T-dependent Ag, phosphocholine conjugated to keyhole limpet hemocyanin, ppc1-5 NAA B cells mounted a quick IgM Ab response and entered germinal centers, but they failed to differentiate to IgG-producing cells during late primary and memory responses. Hybridomas and cDNA clones derived from the immunized mice included many IgM NAA-producing cells, but IgG NAA clones were extremely rare. Instead, many of the IgG B cells replaced their IgH transgene with an endogenous V H gene and produced non-autoreactive Abs. These results indicate that although NAA B cells are positively selected in the preimmune repertoire and can participate in early IgM Ab response, they are subjected to regulatory mechanisms that prevent them from developing to high-affinity IgG autoantibody production. This would explain, at least in part, why NAAs do not cause autoimmunity in most individuals.
The Regulation and Activation Potential of Autoreactive B Cells
Immunologic Research, 2003
Anti-double-stranded DNA (dsDNA) B cells persist even in nonautoimmune-prone animals. In this review, we summarize data regarding the activation potential of these cells. Provision of cognate CD4 T cell help to anti-dsDNA B cells in nonautoimmune mice not only drives their maturation and entry into the B cell follicle, but also leads to secretion of anti-dsDNA autoantibodies. Intriguingly, if T regulatory cells are provided along with T helper cells, the antibody response of anti-dsDNA B cells is diminished. We have also found that T-independent stimulation with CpG oligodeoxynucleotides leads to the proliferation and enhanced recovery of anti-dsDNA B cells in vitro. These data suggest that control of anti-dsDNA antibody production may rely on elements from both the innate and adaptive arms of the immune system.
Alternative mechanisms of receptor editing in autoreactive B cells
Proceedings of the National Academy of Sciences, 2011
Pathogenic anti-DNA antibodies expressed in systemic lupus erythematosis bind DNA mainly through electrostatic interactions between the positively charged Arg residues of the antibody complementarity determining region (CDR) and the negatively charged phosphate groups of DNA. The importance of Arg in CDR3 for DNA binding has been shown in mice with transgenes coding for anti-DNA V H regions; there is also a close correlation between arginines in CDR3 of antibodies and DNA binding. Codons for Arg can readily be formed by V(D)J rearrangement; thereby, antibodies that bind DNA are part of the preimmune repertoire. Anti-DNAs in healthy mice are regulated by receptor editing, a mechanism that replaces κ light (L) chains compatible with DNA binding with κ L chains that harbor aspartic residues. This negatively charged amino acid is thought to neutralize Arg sites in the V H . Editing by replacement is allowed at the κ locus, because the rearranged VJ is nested between unrearranged Vs and Js. However, neither λ nor heavy (H) chain loci are organized so as to allow such second rearrangements. In this study, we analyze regulation of anti-DNA H chains in mice that lack the κ locus, κ-/κmice. These mice show that the endogenous preimmune repertoire does indeed include a high frequency of antibodies with Arg in their CDR3s (putative anti-DNAs) and they are associated mainly with the editor L chain λx. The editing mechanisms in the case of λ-expressing B cells include L chain allelic inclusion and V H replacement. autoimmunity | tolerance A nti-DNA antibodies bind DNA mainly through electrostatic interactions between the positively charged Arg (R) residues of the antibody complementarity determining regions (CDRs) and the negatively charged DNA phosphodiester backbone (1). Arg enrichment has been demonstrated in the protein sequences of anti-DNA antibody heavy (H) chains (2, 3). In addition, reverse mutagenesis of an H chain Arg to a germline amino acid weakened DNA binding, whereas forward mutagenesis with additional Arg residues enhanced DNA binding (1). The predominant occurrence of Arg residues in the V H -encoded CDRs of anti-DNA antibodies indicates a dominant role for V H in DNA binding, and the DNA specificity of these H chains persists when paired with a wide variety of light (L) chains (4-6). There are exceptional L chains (4 Vκ L chains of 95 functional Vκ genes and 1 Vλ L chain of 4 functional Vλ L chains) of the mouse that modify or veto the DNA-binding quality of . These editor L chains are characterized by a high content of aspartate, a negatively charged amino acid that efficiently neutralizes the positively charged Arg residues of anti-DNA H chains (4). B cells that express an anti-DNA V H with a noneditor L chain can undergo further L chain rearrangement. If the original L chain is replaced by an editor L chain, the B cell will be tolerized (4, 7). Similarly, MHC class I-reactive B cells (found in 3-83μ transgenic mice) that encounter autoantigen in the bone marrow continue rearrangement and change receptor specificity by replacing the transgenic 3-83 κ L chain with an endogenous κ or λ L chain (9, 10).
European Journal of Immunology, 2003
We have previously constructed knock-in (C57BL/6×BALB/c) F1 mice, each expressing an anti-DNA heavy (H) chain (D42), combined with one of three different light (L) chains, namely Vκ1-Jκ1, Vκ4-Jκ4 or Vκ8-Jκ5. All of these H/L chain combinations bind DNA with similar affinity and fine specificity. However, while mice carrying Vκ1-Jκ1-transgenic L chain were tolerized almost exclusively by L chain receptor editing, the mice expressing Vκ8-Jκ5 L chains utilized clonal anergy as their principal mechanism of B cell tolerance. Vκ4-Jκ4 targeted mice exhibited an intermediate phenotype. In the present study, these three H/L chain combinations were backcrossed onto the autoimmune NZB/NZW F1 mice. We find that the mechanism of clonal anergy is abrogated in these mice, but that receptor editing is maintained. Moreover, diseased NZB/NZW mice utilize L chain secondary rearrangements for the generation of high-affinity, anti-dsDNA-producing B cells from low-affinity precursors. The edited B cell clones are not deleted or anergized in the autoimmune animal; rather they are selected for activation, class-switching and affinity maturation by somatic mutation. These results suggest that B cell receptor editing plays an important role not only in tolerance induction, but also in generating high-affinity autoreactive B cells in autoimmune diseases.
Journal of Experimental Medicine, 1996
To assess the sensitivity of B cell tolerance with respect to receptor/autoantigen affinity, we identified low affinity ligands to the 3-83 (anti-major histocompatibility complex class I) antibody and tested the ability of these ligands to induce central and peripheral tolerance in 3-83 transgenic mice. Several class I protein aUoforms, including K bin3 and D k, showed remarkably low, but detectable, affinity to 3-83. The 3-83 antibody bound K b with K A "-'2 × 105 M-1 and bound 10-fold more weakly to the K bin3 (K A "-'2 × 104 M -1) and D k antigens. Breeding 3-83 immunoglobulin transgenic mice with mice expressing these ultralow affinity m bm3 and D k ligands resulted in virtually complete deletion of the autoreactive B cells from the peripheral lymphoid tissues. These low affinity antigens also induced receptor editing, as measured by elevated RAG mR.NA levels in the bone marrow and excess levels of id-variant B cells bearing light chains in the spleen. Reactive class I antigens were also able to mediate deletion of mature B cells when injected into the peritoneal cavity of 3-83 transgenic mice. Although the highest affinity ligand, K k, was consistently able to induce elimination of the 3-83 peritoneal B cells, the lower affinity ligands were only partially effective. These results demonstrate the remarkable sensitivity of the deletion and receptor-editing mechanisms in immature B cells, and may suggest a higher affinity threshold for deletion of peripheral, mature B cells.