Allelic exclusion in transgenic mice expressing a heavy chain disease‐like human μ protein

Corcos, Daniel; Iglesias, Antonio; Dunda, Olga; Bucchini, Danielle; Jami, Jacques

doi:10.1002/eji.1830211110

Cited by 22 publications

(28 citation statements)

References 34 publications

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“…The first domain of the constant region, CH1, is spliced out because of the loss of a consensus splice signal (5,6). CH1 exon loss also has been described in other mammals, albeit associated with disease, e.g., in mouse myelomas (7) and human HC disease (HCD) (8)(9)(10).…”

Section: Onventional Antibodies Contain Two Heavy and Light Chains mentioning

confidence: 99%

Generation of heavy-chain-only antibodies in mice

Janssens¹,

Dekker²,

Hendriks

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

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We have generated transgenic mice containing hybrid llama͞ human antibody loci that contain two llama variable regions and the human D, J, and C and͞or C␥ constant regions. Such loci rearrange productively and rescue B cell development efficiently without LC rearrangement. Heavy-chain-only antibodies (HCAb) are expressed at high levels, provided that the CH1 domain is deleted from the constant regions. HCAb production does not require an IgM stage for effective pre-B cell signaling. Antigenspecific heavy-chain-only IgM or IgGs are produced upon immunization. The IgG is dimeric, whereas IgM is multimeric. The chimeric HCAb loci are subject to allelic exclusion, but several copies of the transgenic locus can be rearranged and expressed successfully on the same allele in the same cell. Such cells are not subject to negative selection. The mice produce a full antibody repertoire and provide a previously undescribed avenue to produce specific human HCAb in the future.immunoglobulin rearrangement ͉ transgenic C onventional antibodies contain two heavy and light chains (LC) coded for by heavy and LC loci. B cell development and antibody production starts in the bone marrow (BM) by heavy chain (HC) VDJ recombination and expression of IgM associated with a surrogate LC on the cell surface. In a second round of recombination, one of the LC rearranges in pre-B cells. If successful, the B cells undergo selection, affinity maturation, and switching to different HC constant regions to result in B cells, which express tetrameric antibodies of different isotypes (IgA, IgG, and IgE). Normally absence of HC or LC expression leads to arrest of B cell development. However, some species produce HC-only antibodies (HCAb) as part of their normal B cell development and repertoire. The best-known HCAb (i.e., no LC) are IgG2 and IgG3 in camelids (1). They undergo antigen-mediated selection and affinity maturation, and their variable domains are subject to somatic hypermutation (2, 3). HCAb are thought to recognize unusual epitopes, such as clefts on the antigen surface (4). The first domain of the constant region, CH1, is spliced out because of the loss of a consensus splice signal (5, 6). CH1 exon loss also has been described in other mammals, albeit associated with disease, e.g., in mouse myelomas (7) and human HC disease (HCD) (8-10).Camelid HCAbs contain a complete VDJ region. Its size, stability, specificity, and solubility have generated considerable biotechnological interest. The antigen-binding site, a single-variable domain (VHH), resembles VH of conventional Abs. However, differences in FR2 and CDR3 prevent VHH to pair with a variable LC, whereas hydrophilic amino acids provide solubility (11). HCAb of the IgM class have not been found in camelids, suggesting that the IgM ϩ stage of HCAb formation is very transient and͞or circumvented.Murine NSO myeloma cells can express a rearranged camelid VHH-␥2a gene (12) and, recently, the same gene was expressed in transgenic mice (13). Here, we describe transgenic mice containing various...

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Section: Onventional Antibodies Contain Two Heavy and Light Chains mentioning

confidence: 99%

Generation of heavy-chain-only antibodies in mice

Janssens¹,

Dekker²,

Hendriks

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

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“…⌬V -and h Sp6-transgenic proteins cause allelic exclusion, and almost all spleen B cells from ⌬V -6-and h Sp6-39-transgenic mice express neither mouse IgM nor IgD on their surface (5,7). For this reason, B cells from these transgenic mice were identified by surface staining for developmentally regulated markers.…”

Section: Characterization Of B Cell Populations In ⌬V Mice On the Balmentioning

confidence: 99%

“…In cancer cells from patients suffering from H chain disease, a B cell neoplasia, the H chain is truncated and lacks a functional variable domain (3,4). Deletion of the variable domain of the human H chain, as found in several cases of H chain disease, allows surface expression of a truncated BCR in the absence of L chain (5,6). This truncated BCR lacking an Ag binding domain has constitutive activity, because in transgenic mice the membrane ⌬V protein of human origin causes inhibition of endogenous H chain gene rearrangements and relieves the requirement for surrogate L chain in pre-B cell development (5,7).…”

mentioning

confidence: 99%

“…Deletion of the variable domain of the human H chain, as found in several cases of H chain disease, allows surface expression of a truncated BCR in the absence of L chain (5,6). This truncated BCR lacking an Ag binding domain has constitutive activity, because in transgenic mice the membrane ⌬V protein of human origin causes inhibition of endogenous H chain gene rearrangements and relieves the requirement for surrogate L chain in pre-B cell development (5,7). The constitutive activity of this truncated BCR is reminiscent of that observed for oncogenic growth factor receptors (8).…”

mentioning

confidence: 99%

“…We have previously reported that, in ⌬V mice, there is a reduction in peripheral B cell numbers and very low levels of human protein are found in the serum (5). It has also been determined that ⌬V B cells have a short half-life (17).…”

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confidence: 99%

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Expression of a V Region-Less B Cell Receptor Confers a Tolerance-Like Phenotype on Transgenic B Cells

Corcos

Grandien

Vázquez

et al. 2001

The Journal of Immunology

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Neoplastic B cells from H chain disease patients express a truncated B cell receptor (BCR), comprising a membrane Ig that lacks part of its extracellular domain. It has been speculated that deletion of the Ag binding domain would confer a constitutive activity on the BCR, as it has been shown for oncogenic growth factor receptors. A V region-less BCR has constitutive activity, because in transgenic mice it causes inhibition of endogenous H chain gene rearrangements and relieves the requirement for surrogate L chain in pre-B cell development. However, it has been speculated that normal Ag receptors also display constitutive activity. Here we show that transgenic B cells expressing a membrane H chain disease protein on their surface are phenotypically and functionally similar to B cells developing in the presence of their cognate Ag and that cells with normal levels of mutant BCR are eliminated in spleen via a bcl-2 sensitive pathway while progressing toward the mature stage. In contrast, cells with lower levels of mutant receptors develop as mature B cells. These findings support the view that the truncated BCR has a constitutive activity that mimics ligand binding, in analogy to what has been shown for oncogenic growth factor receptors.

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The role of the B cell receptor V region in peripheral B cell survival

Rosado

Freitas

1998

Eur. J. Immunol.

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We investigate the role of the antigen-specific B cell receptor (BCR) in the establishment and maintenance of the peripheral B cell pools. We studied the fate of a population of transgenic B cells expressing a BCR without V region (Tg ¿ V ?). We found that the Tg ¿ V ? B cells can populate the peripheral B cell pools in the absence of other B cells, but when in the presence of a second population of non-transgenic B cells, they are virtually absent from the mature B cell compartments. By studying the rate of accumulation of 5-bromo-2'-deoxyuridine we show that the peripheral Tg ¿ V ? B cells have a shorter lifespan compared to non-transgenic B cells. By directly comparing the fate of two populations of transgenic B cells, either lacking or expressing a V region, we were able to assign the poorest competitive ability and the short peripheral survival of the Tg ¿ V ? B cells to the lack of an antigen-binding site. The results obtained support the involvement of the V region in the persistence of peripheral B cell populations.

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Allelic exclusion in transgenic mice expressing a heavy chain disease‐like human μ protein

Cited by 22 publications

References 34 publications

Generation of heavy-chain-only antibodies in mice

Generation of heavy-chain-only antibodies in mice

Expression of a V Region-Less B Cell Receptor Confers a Tolerance-Like Phenotype on Transgenic B Cells

The role of the B cell receptor V region in peripheral B cell survival

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