Rearrangement of Mouse Immunoglobulin Kappa Deleting Element Recombining Sequence Promotes Immune Tolerance and Lambda B Cell Production

Transcription of the mouse immunoglobulin kappa gene is controlled by two enhancers: the intronic enhancer (Ei) that occurs between the joining (J kappa) and constant (C kappa) exons and the 3' enhancer (E3') located 8.5 kb downstream of the gene. To understand the role of E3' in the activation of the mouse immunoglobulin kappa gene, we studied its chromatin structure in cultured B-cell lines arrested at various stages of differentiation. We found that 120 bp of the enhancer's transcriptional core becomes DNase I hypersensitive early in B-cell development. Genomic footprinting of pro-B and pre-B cells localized this chromatin alteration to B-cell-specific protections at the region including the direct repeat (DR) and the sequence downstream of the DR (DS), the PU.1-NFEM-5 site, and the core's E-box motif, identifying bound transcription factors prior to kappa gene rearrangement. Early footprints were, however, not detected at downstream sites proposed to play a negative role in transcription. The early chromatin structure persisted through the mature B-cell stage but underwent a dramatic shift in plasma cells, correlating with the loss of guanosine protection within the DR-DS junction and the appearance of novel footprints at a GC-rich motif upstream and the NF-E1 (YY1/delta)-binding site downstream. Gel shift analysis demonstrated that the DR-DS junction is bound by a factor with properties similar to those of BSAP (B-cell-specific activator protein). These results reveal developmental-stage-specific changes in the composition of nuclear factors bound to E3', clarify the role of factors that bind constitutively in vitro, and point to the differentiation of mature B cells to plasma cells as an important transitional point in the function of this enhancer. The observed changes in nuclear factor composition were accompanied by the rearrangement of positioned nucleosomes that flank the core region, suggesting a role for both nuclear factors and chromatin structure in modulating kappa E3' function during B-cell development. The functional implications of the observed chromatin alterations are discussed in the context of recent studies on kappa E3' and the factors that bind to it.

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Inhibitor treatment by rituximabin congenital haemophilia A

Hämostaseologie ◽

10.1055/s-0037-1617028 ◽

2009 ◽

Vol 29 (02) ◽

pp. 151-154 ◽

Cited By ~ 13

Author(s):

Escuriola Ettingshausen ◽

R. Linde ◽

G. Kropshofer ◽

L.-B. Zimmerhackl ◽

W. Kreuz ◽

...

Keyword(s):

B Cell ◽

Immune Tolerance ◽

High Titre ◽

Clotting Factor ◽

Severe Bleeding ◽

High Morbidity ◽

Haemophilia A ◽

Concomitant Treatment ◽

Bleeding Tendency ◽

Severe Haemophilia

SummaryThe development of neutralizing alloanti-bodies (inhibitors) to factor VIII (FVIII) is one of the most serious complications in the treatment of haemophiliacs. Inhibitors occur in approximately 20 to 30% of previously untreated patients (PUPs), predominantly children, with severe haemophilia A within the first 50 exposure days (ED). Immune tolerance induction (ITI) leads to complete elimination of the inhibitor in up to 80% of the patients and offers the possibility to restore regular FVIII prophylaxis. However, patients with high titre inhibitors, in whom standard ITI fails, usually impose with high morbidity and mortality and therefore prompting physicians to alternate therapy regimens. Rituximab, an anti-CD 20 monoclonal antibody has been successfully used in children and adults for the management of B-cell mediated disorders. We report on the use of a new protocol including rituximab in two adolescents with severe haemophilia A and high titre inhibitors, severe bleeding tendency and high clotting factor consumption after failing standard ITI. Both patients received a concomitant treatment with FVIII according to the Bonn protocol, cyclosporine A and immunoglobulin. Treatment with rituximab resulted in a temporary B-cell depletion leading to the disappearance of the inhibitor. FVIII recovery and half-life turned towards normal ranges. In patient 1 the inhibitor reappeared 14 months after the last rituximab administration. In patient 2 complete immune tolerance could be achieved for 60 months. Bleeding frequency diminished significantly and clinical joint status improved in both patients. In patient 1 the treatment course was complicated by aspergillosis and hepatitis B infection. Conclusion: Rituximab may be favourable for patients with congenital haemophilia, high-titre inhibitors and a severe clinical course in whom standard ITI has failed. Prospective studies are required to determine safety, efficacy and predictors of success.

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Faculty Opinions recommendation of Cutting edge: impaired transitional B cell production and selection in the nonobese diabetic mouse.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1032845.374511 ◽

2006 ◽

Author(s):

David Serreze

Keyword(s):

B Cell ◽

Diabetic Mouse ◽

Cutting Edge ◽

Nonobese Diabetic Mouse ◽

Cell Production ◽

Nonobese Diabetic ◽

Transitional B Cell

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B Cell Production in Adult Rats

Microenvironments in the Lymphoid System ◽

10.1007/978-1-4613-2463-8_8 ◽

1985 ◽

pp. 65-71

Author(s):

H. Bazin ◽

B. Platteau ◽

I. C. M. MacLennan ◽

N. S. A. Stuart ◽

M. Khan ◽

...

Keyword(s):

B Cell ◽

Adult Rats ◽

Cell Production

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Sequence diversity within a subgroup of mouse immunoglobulin kappa chains controlled by the IgK-Ef2 locus.

Journal of Experimental Medicine ◽

10.1084/jem.154.1.146 ◽

1981 ◽

Vol 154 (1) ◽

pp. 146-155 ◽

Cited By ~ 13

Author(s):

C Lazure ◽

W T Hum ◽

D M Gibson

Keyword(s):

Normal Mouse ◽

Sequence Diversity ◽

The Other ◽

Light Chains ◽

Chromosome 6 ◽

Immunoglobulin Kappa ◽

Mouse Immunoglobulin ◽

Complete Sequencing ◽

Polymorphic Bands ◽

V Region

We previously showed that a chromosome 6 locus, IgK-Ef2, controls a pair of prominent bands in normal mouse light-chain isoelectric focusing profiles. Screening of myeloma light chains derived from BALB/c mice (an IgK-EF2 alpha strain) led to the identification of seven light chains cofocusing with the polymorphic bands controlled by IgK-Ef2. Complete sequencing of the variable (V) regions of four of the light chains indicates that they are all members of the same subgroup (Vk-1A) and they differ from one another by 1--3 substitutions. One of the protein differs from the prototype V-region sequence only in the deletion of a single residue at position 95 immediately preceding of J region. The other two differ from the protype V region by 3 (two framework [fr], one complementarity-determined [cdr]) and one (fr) residues, respectively. Complete V-region sequences of two closely related light chains derived from NZB mice (an IgK-Ef2b strain) indicate the NZB proteins are derived from a distinct Vk gene (Vk-1B), differing by four substitutions from the Vk-1A sequence. The results suggest that the IgK-Ef2 polymorphism may be a result of, at least in part, the loss of the gene(s) coding for the Vk-1A subgroups in IgK-Ef2b strains of mice. The nature of the sequence diversity found in the Vk-1A subgroup indicates that either it is coded by a repeated series of virtually identical genes or that somatic mutation of a single Vk-1A gene may give rise to substitutions in framework as well as cdr regions.

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B-cell nuclear proteins binding in vitro to the human immunoglobulin kappa enhancer: localization by exonuclease protection.

Molecular and Cellular Biology ◽

10.1128/mcb.7.5.1815 ◽

1987 ◽

Vol 7 (5) ◽

pp. 1815-1822 ◽

Cited By ~ 8

Author(s):

J M Gimble ◽

D Levens ◽

E E Max

Keyword(s):

Protein Binding ◽

B Cell ◽

Base Pair ◽

Consensus Sequence ◽

Dimethyl Sulfate ◽

Simian Virus 40 ◽

Human Immunoglobulin ◽

Core Element ◽

Immunoglobulin Kappa

Proteins capable of interacting with the enhancer of the immunoglobulin kappa gene in vitro have been detected in extracts of nuclei from human B cells and from human, mouse, and rabbit spleens. The experiments, based on an exonuclease protection technique, demonstrate nuclear protein factors binding to a 30- to 35-base-pair domain containing both the simian virus 40 enhancer core element (TTTCCA) and the octamer CAGGTGGC that was previously identified as the consensus sequence for protein-binding sites in the murine immunoglobulin heavy-chain enhancer. This 30- to 35-base-pair domain in the human kappa enhancer is homologous to a site of protein binding detected in the murine kappa enhancer by other investigators using a gel retardation assay. Our results complement in vivo dimethyl sulfate footprinting studies of the human immunoglobulin kappa enhancer which demonstrated B cell-specific changes in guanine reactivity immediately 5' to the consensus octamer. Together, these findings suggest that DNA-binding proteins in B-cell nuclei interact with the 5' portion of the human kappa-gene enhancer. Such proteins could play a role in the B cell-specific transcription of the human immunoglobulin kappa gene.

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