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Enforced Bcl-2 expression inhibits antigen-mediated clonal elimination of peripheral B cells in an antigen dose-dependent manner and promotes receptor editing in autoreactive, immature B cells.

Lang J, Arnold B, Hammerling G, Harris AW, Korsmeyer S, Russell D, Strasser A, Nemazee D - J. Exp. Med. (1997)

Bottom Line: Furthermore, Bcl-2 protected peritoneal B-2 B cells from deletion mediated by acute antigen exposure, but this protection could be overcome by higher antigen dose.In contrast to its ability to block peripheral self-tolerance, Bcl-2 overexpression failed to inhibit central tolerance induced by bone marrow antigen expression, but instead, enhanced the receptor editing process.These studies indicate that apoptosis plays distinct roles in central and peripheral B cell tolerance.

View Article: PubMed Central - PubMed

Affiliation: Division of Basic Sciences, Department of Pediatrics, National Jewish Medical and Research Center, Denver, Colorado 80206, USA.

ABSTRACT
The mechanisms that establish immune tolerance in immature and mature B cells appear to be distinct. Membrane-bound autoantigen is thought to induce developmental arrest and receptor editing in immature B cells, whereas mature B cells have shortened lifespans when exposed to the same stimulus. In this study, we used Emu-bcl-2-22 transgenic (Tg) mice to test the prediction that enforced expression of the Bcl-2 apoptotic inhibitor in B cells would rescue mature, but not immature, B cells from tolerance induction. To monitor tolerance to the natural membrane autoantigen H-2Kb, we bred 3-83mudelta (anti-Kk,b) Ig Tg mice to H-2(b) mice or to mice expressing transgene-driven Kb in the periphery. In 3-83mudelta/bcl-2 Tg mice, deletion of autoreactive B cells induced by peripheral Kb antigen expression in the liver (MT-Kb Tg) or epithelia (KerIV-Kb Tg), was partly or completely inhibited, respectively. Furthermore, Bcl-2 protected peritoneal B-2 B cells from deletion mediated by acute antigen exposure, but this protection could be overcome by higher antigen dose. In contrast to its ability to block peripheral self-tolerance, Bcl-2 overexpression failed to inhibit central tolerance induced by bone marrow antigen expression, but instead, enhanced the receptor editing process. These studies indicate that apoptosis plays distinct roles in central and peripheral B cell tolerance.

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Appearance of immature B cells in spleen of CD (H-2b) bcl-2/RAG-1–deficient mice. Spleen cells from mice of the indicated genotypes were stained for presence of 3–83 B cells with anticlonotype (54.1)  and anti-IgM antibodies (A), and anti-IgM and anti-B220 antibodies (B).  The immature B cells have low levels of Id and lack detectable sIgM (arrows). The NDTg control used in this particular experiment was 3–83μδ  homozygous, which consistently show reduced B cell populations. Data  shown represent one of five similar experiments.
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Figure 6: Appearance of immature B cells in spleen of CD (H-2b) bcl-2/RAG-1–deficient mice. Spleen cells from mice of the indicated genotypes were stained for presence of 3–83 B cells with anticlonotype (54.1) and anti-IgM antibodies (A), and anti-IgM and anti-B220 antibodies (B). The immature B cells have low levels of Id and lack detectable sIgM (arrows). The NDTg control used in this particular experiment was 3–83μδ homozygous, which consistently show reduced B cell populations. Data shown represent one of five similar experiments.

Mentions: In some CDTg/bcl-2 mice (13/21), a population of IgM−, B220+ B cells was detected in the spleen and, to a lesser extent, in the lymph nodes. To further characterize this population in a context in which receptor editing could not occur, we generated CDTg/bcl-2/RAG-1–deficient mice (57). Again, no strongly Id+ cells were detected in the peripheral lymphoid organs (Fig. 6 A; Table 1), but a significant population of IgM−, B220+, Idlo cells was detected in the spleen of the CDTg/bcl-2/RAG-1−/− mice (Fig. 6, A and B, note arrows), and a similar population was detected to a lesser extent in CDTg/RAG-1−/− mice without Bcl-2 overexpression. These IgM−, B220+ cells were CD23−, κlo, IgDlo, and CR1/2− (data not shown) which is indicative of immature B cells as has been previously reported in Bcl-2 overexpressing Ig Tg mice (9). Also indicative of immature B cells, these cells expressed RAG-2 messenger RNA transcripts (data not shown). These cells failed to secrete antibodies in LPS cultures and in vivo, as no antibodies were detected in the serum (Fig. 4 C). In CDTg/RAG-1−/− mice, no serum IgM was detected because RAG deficiency prevented development of Id− B cells (Fig. 4 D). These splenic immature B cells were short lived, as ∼50% of the cells had incorporated BrdU+ after 1 wk compared to only ∼20% of B220+ cells from non-Tg or NDTg mice (data not shown). Thus, in contrast to its effect on peripheral tolerance, the bcl-2 transgene appeared to have only a subtle effect on central B cell tolerance, allowing a subset of autoreactive nonfunctional, immature B cells to survive in the spleen for a short time.


Enforced Bcl-2 expression inhibits antigen-mediated clonal elimination of peripheral B cells in an antigen dose-dependent manner and promotes receptor editing in autoreactive, immature B cells.

Lang J, Arnold B, Hammerling G, Harris AW, Korsmeyer S, Russell D, Strasser A, Nemazee D - J. Exp. Med. (1997)

Appearance of immature B cells in spleen of CD (H-2b) bcl-2/RAG-1–deficient mice. Spleen cells from mice of the indicated genotypes were stained for presence of 3–83 B cells with anticlonotype (54.1)  and anti-IgM antibodies (A), and anti-IgM and anti-B220 antibodies (B).  The immature B cells have low levels of Id and lack detectable sIgM (arrows). The NDTg control used in this particular experiment was 3–83μδ  homozygous, which consistently show reduced B cell populations. Data  shown represent one of five similar experiments.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2199120&req=5

Figure 6: Appearance of immature B cells in spleen of CD (H-2b) bcl-2/RAG-1–deficient mice. Spleen cells from mice of the indicated genotypes were stained for presence of 3–83 B cells with anticlonotype (54.1) and anti-IgM antibodies (A), and anti-IgM and anti-B220 antibodies (B). The immature B cells have low levels of Id and lack detectable sIgM (arrows). The NDTg control used in this particular experiment was 3–83μδ homozygous, which consistently show reduced B cell populations. Data shown represent one of five similar experiments.
Mentions: In some CDTg/bcl-2 mice (13/21), a population of IgM−, B220+ B cells was detected in the spleen and, to a lesser extent, in the lymph nodes. To further characterize this population in a context in which receptor editing could not occur, we generated CDTg/bcl-2/RAG-1–deficient mice (57). Again, no strongly Id+ cells were detected in the peripheral lymphoid organs (Fig. 6 A; Table 1), but a significant population of IgM−, B220+, Idlo cells was detected in the spleen of the CDTg/bcl-2/RAG-1−/− mice (Fig. 6, A and B, note arrows), and a similar population was detected to a lesser extent in CDTg/RAG-1−/− mice without Bcl-2 overexpression. These IgM−, B220+ cells were CD23−, κlo, IgDlo, and CR1/2− (data not shown) which is indicative of immature B cells as has been previously reported in Bcl-2 overexpressing Ig Tg mice (9). Also indicative of immature B cells, these cells expressed RAG-2 messenger RNA transcripts (data not shown). These cells failed to secrete antibodies in LPS cultures and in vivo, as no antibodies were detected in the serum (Fig. 4 C). In CDTg/RAG-1−/− mice, no serum IgM was detected because RAG deficiency prevented development of Id− B cells (Fig. 4 D). These splenic immature B cells were short lived, as ∼50% of the cells had incorporated BrdU+ after 1 wk compared to only ∼20% of B220+ cells from non-Tg or NDTg mice (data not shown). Thus, in contrast to its effect on peripheral tolerance, the bcl-2 transgene appeared to have only a subtle effect on central B cell tolerance, allowing a subset of autoreactive nonfunctional, immature B cells to survive in the spleen for a short time.

Bottom Line: Furthermore, Bcl-2 protected peritoneal B-2 B cells from deletion mediated by acute antigen exposure, but this protection could be overcome by higher antigen dose.In contrast to its ability to block peripheral self-tolerance, Bcl-2 overexpression failed to inhibit central tolerance induced by bone marrow antigen expression, but instead, enhanced the receptor editing process.These studies indicate that apoptosis plays distinct roles in central and peripheral B cell tolerance.

View Article: PubMed Central - PubMed

Affiliation: Division of Basic Sciences, Department of Pediatrics, National Jewish Medical and Research Center, Denver, Colorado 80206, USA.

ABSTRACT
The mechanisms that establish immune tolerance in immature and mature B cells appear to be distinct. Membrane-bound autoantigen is thought to induce developmental arrest and receptor editing in immature B cells, whereas mature B cells have shortened lifespans when exposed to the same stimulus. In this study, we used Emu-bcl-2-22 transgenic (Tg) mice to test the prediction that enforced expression of the Bcl-2 apoptotic inhibitor in B cells would rescue mature, but not immature, B cells from tolerance induction. To monitor tolerance to the natural membrane autoantigen H-2Kb, we bred 3-83mudelta (anti-Kk,b) Ig Tg mice to H-2(b) mice or to mice expressing transgene-driven Kb in the periphery. In 3-83mudelta/bcl-2 Tg mice, deletion of autoreactive B cells induced by peripheral Kb antigen expression in the liver (MT-Kb Tg) or epithelia (KerIV-Kb Tg), was partly or completely inhibited, respectively. Furthermore, Bcl-2 protected peritoneal B-2 B cells from deletion mediated by acute antigen exposure, but this protection could be overcome by higher antigen dose. In contrast to its ability to block peripheral self-tolerance, Bcl-2 overexpression failed to inhibit central tolerance induced by bone marrow antigen expression, but instead, enhanced the receptor editing process. These studies indicate that apoptosis plays distinct roles in central and peripheral B cell tolerance.

Show MeSH
Related in: MedlinePlus