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Editing anti-DNA B cells by Vlambdax.

Li Y, Louzoun Y, Weigert M - J. Exp. Med. (2004)

Bottom Line: However, the lambda locus, either of man or mouse, does not allow V gene replacement.We have found that in anti-DNA heavy chain transgenic mice (tgs) VH3H9/56R, B cells that express anti-DNA receptors comprised of lambda1 in association with an anti-DNA heavy chain often coexpress a kappa chain that prevents DNA binding.Here we describe a mechanism of preventing DNA binding by expression of a rarely used member of the Vlambda family, Vlambdax.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Biology, Princeton University, NJ 08544, USA. yijinli@uchicago.edu

ABSTRACT
Receptor editing is performed by replacement of Vkappa genes that contribute to autoreactivity. In addition, the Ckappa locus can be deleted by Vkappa rearrangement to intronic or 3' of Ckappa RS sequences (also referred to as kappa deletion elements). B cells that delete the Ckappa can then express lambda light chains. However, the lambda locus, either of man or mouse, does not allow V gene replacement. Nor does it appear to be deleted. Therefore, editing of autoreactive lambda B cells may require alternative pathways. We have found that in anti-DNA heavy chain transgenic mice (tgs) VH3H9/56R, B cells that express anti-DNA receptors comprised of lambda1 in association with an anti-DNA heavy chain often coexpress a kappa chain that prevents DNA binding. We speculate that such isotypically included cells may have low anti-DNA receptor densities, a feature that may lead to self-tolerance. Here we describe a mechanism of preventing DNA binding by expression of a rarely used member of the Vlambda family, Vlambdax. The lambdax B cells of the tgs also express CD25 and may represent B cells that have exhausted light chain editing possibilities.

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Deletion of κ L chain loci increases the frequency of CD25+ B cells that express Vλx. Spleen cells from VH3H9/56R and κ L chain–deficient mice (Jκdel/κ+, Jκ/Cκ deletion on one κ allele; Jκdel/Jκdel, deletion on both alleles) with or without the 3H9/56R transgene were stained with anti-B220, CD25, κ, λ, IgM, and IgD. The percentages of the CD25+/B220+ cells in the B220+ B cells are indicated in the top. On the middle and bottom panels are the κ/λ staining of cells in the CD25+/B220+ and the B220+ gates, respectively.
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fig2: Deletion of κ L chain loci increases the frequency of CD25+ B cells that express Vλx. Spleen cells from VH3H9/56R and κ L chain–deficient mice (Jκdel/κ+, Jκ/Cκ deletion on one κ allele; Jκdel/Jκdel, deletion on both alleles) with or without the 3H9/56R transgene were stained with anti-B220, CD25, κ, λ, IgM, and IgD. The percentages of the CD25+/B220+ cells in the B220+ B cells are indicated in the top. On the middle and bottom panels are the κ/λ staining of cells in the CD25+/B220+ and the B220+ gates, respectively.

Mentions: Like normal mature follicular B cells, these CD25+ B cells are IgM+ and IgD+. Yet they attracted our attention because no L chain expression could be detected by the commercially available anti-κ or anti-λ antibodies (Fig. 1 B). However, the frequency of these CD25+ B cells is higher in VH3H9/56R κ-deficient mice, suggesting that these B cells do express λ chain. The CD25+ population size is inversely proportional to the number of κ alleles. Deletion of one κ allele increases the percentage to 18.1 (SD 3.6, n = 4) and 55.0% (SD 18.1, n = 4) when both κs are deleted (Fig. 2). The most likely λ chain is the Vλx. Although this Vλ is located in the Jλ2-Cλ2 locus and is usually rearranged to Jλ2, its V region is only 33% identical to the Vλ2 (Identity to Vλ1 and mouse Vκs is also <35% but homology to human Vλ5-6 and Vλ5-1 is high, at 75 and 70%, respectively.). If anti-λ antibodies are directed to the V region, then Vλx/Cλ2 may not be recognized by these reagents. Indeed, molecular analysis of L chain rearrangement (see below) shows that Vλx is rearranged in the CD25+ population.


Editing anti-DNA B cells by Vlambdax.

Li Y, Louzoun Y, Weigert M - J. Exp. Med. (2004)

Deletion of κ L chain loci increases the frequency of CD25+ B cells that express Vλx. Spleen cells from VH3H9/56R and κ L chain–deficient mice (Jκdel/κ+, Jκ/Cκ deletion on one κ allele; Jκdel/Jκdel, deletion on both alleles) with or without the 3H9/56R transgene were stained with anti-B220, CD25, κ, λ, IgM, and IgD. The percentages of the CD25+/B220+ cells in the B220+ B cells are indicated in the top. On the middle and bottom panels are the κ/λ staining of cells in the CD25+/B220+ and the B220+ gates, respectively.
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Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2211795&req=5

fig2: Deletion of κ L chain loci increases the frequency of CD25+ B cells that express Vλx. Spleen cells from VH3H9/56R and κ L chain–deficient mice (Jκdel/κ+, Jκ/Cκ deletion on one κ allele; Jκdel/Jκdel, deletion on both alleles) with or without the 3H9/56R transgene were stained with anti-B220, CD25, κ, λ, IgM, and IgD. The percentages of the CD25+/B220+ cells in the B220+ B cells are indicated in the top. On the middle and bottom panels are the κ/λ staining of cells in the CD25+/B220+ and the B220+ gates, respectively.
Mentions: Like normal mature follicular B cells, these CD25+ B cells are IgM+ and IgD+. Yet they attracted our attention because no L chain expression could be detected by the commercially available anti-κ or anti-λ antibodies (Fig. 1 B). However, the frequency of these CD25+ B cells is higher in VH3H9/56R κ-deficient mice, suggesting that these B cells do express λ chain. The CD25+ population size is inversely proportional to the number of κ alleles. Deletion of one κ allele increases the percentage to 18.1 (SD 3.6, n = 4) and 55.0% (SD 18.1, n = 4) when both κs are deleted (Fig. 2). The most likely λ chain is the Vλx. Although this Vλ is located in the Jλ2-Cλ2 locus and is usually rearranged to Jλ2, its V region is only 33% identical to the Vλ2 (Identity to Vλ1 and mouse Vκs is also <35% but homology to human Vλ5-6 and Vλ5-1 is high, at 75 and 70%, respectively.). If anti-λ antibodies are directed to the V region, then Vλx/Cλ2 may not be recognized by these reagents. Indeed, molecular analysis of L chain rearrangement (see below) shows that Vλx is rearranged in the CD25+ population.

Bottom Line: However, the lambda locus, either of man or mouse, does not allow V gene replacement.We have found that in anti-DNA heavy chain transgenic mice (tgs) VH3H9/56R, B cells that express anti-DNA receptors comprised of lambda1 in association with an anti-DNA heavy chain often coexpress a kappa chain that prevents DNA binding.Here we describe a mechanism of preventing DNA binding by expression of a rarely used member of the Vlambda family, Vlambdax.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Biology, Princeton University, NJ 08544, USA. yijinli@uchicago.edu

ABSTRACT
Receptor editing is performed by replacement of Vkappa genes that contribute to autoreactivity. In addition, the Ckappa locus can be deleted by Vkappa rearrangement to intronic or 3' of Ckappa RS sequences (also referred to as kappa deletion elements). B cells that delete the Ckappa can then express lambda light chains. However, the lambda locus, either of man or mouse, does not allow V gene replacement. Nor does it appear to be deleted. Therefore, editing of autoreactive lambda B cells may require alternative pathways. We have found that in anti-DNA heavy chain transgenic mice (tgs) VH3H9/56R, B cells that express anti-DNA receptors comprised of lambda1 in association with an anti-DNA heavy chain often coexpress a kappa chain that prevents DNA binding. We speculate that such isotypically included cells may have low anti-DNA receptor densities, a feature that may lead to self-tolerance. Here we describe a mechanism of preventing DNA binding by expression of a rarely used member of the Vlambda family, Vlambdax. The lambdax B cells of the tgs also express CD25 and may represent B cells that have exhausted light chain editing possibilities.

Show MeSH
Related in: MedlinePlus