scholarly journals Analysis of mutations in immunoglobulin heavy chain variable region genes of microdissected marginal zone (MGZ) B cells suggests that the MGZ of human spleen is a reservoir of memory B cells.

1995 ◽  
Vol 182 (2) ◽  
pp. 559-566 ◽  
Author(s):  
D K Dunn-Walters ◽  
P G Isaacson ◽  
J Spencer
Keyword(s):  
B Cells ◽  
Heavy Chain ◽  
Internal Control ◽  
Marginal Zone ◽  
Variable Region ◽  
Memory B Cells ◽  
White Pulp ◽  
Human Spleen ◽  
Heavy Chain Variable Region ◽  
Vh Genes

The splenic marginal zone (MGZ), which surrounds the mantle zone (MTZ) in human splenic white pulp, contains a phenotypically and morphologically distinct population of B cells. The origin of MGZ B cells is uncertain. Whereas some experiments in rodents have suggested that they are a distinct cell lineage responsible for the immune response to T-independent type 2 antigens, others have suggested that they are memory B cells derived from a germinal center (GC) response. The progeny of a GC reaction is expected to have rearranged immunoglobulin (Ig) genes that are mutated. The distribution of mutations would be expected to reflect the selection of Ig by its affinity for antigen. We have analyzed rearranged Ig heavy chain variable region (VH) 6 and VH 4.21 genes in MGZ and MTZ B cells microdissected from frozen sections of human spleen to determine whether these genes have the properties of an affinity-selected memory B cell population. MTZ B cells contained germline Ig VH genes, confirming previous reports and providing an internal control for mutational analysis. MGZ B cells contained Ig VH genes that were mutated, showing that these cells had been subjected to a mutational mechanism characteristically active in the GC. The rearranged VH 6 genes showed patterns of mutation indicative of an antigen selection process, whereas the distribution of mutations in VH 4.21 genes was not characteristic of gene selection by conventional T-dependent antigen. Our studies provide the first evidence that the human splenic MGZ is a reservoir of memory B cells.

scholarly journals Identification of Functional Human Splenic Memory B Cells by Expression of CD148 and CD27

1998 ◽  
Vol 188 (9) ◽  
pp. 1691-1703 ◽  
Author(s):  
Stuart G. Tangye ◽  
Yong-Jun Liu ◽  
Gregorio Aversa ◽  
Joseph H. Phillips ◽  
Jan E. de Vries
Keyword(s):  
B Cells ◽  
Cell Surface ◽  
Marginal Zone ◽  
Plasma Cells ◽  
Memory B Cells ◽  
White Pulp ◽  
Human Spleen ◽  
Marginal Zone B Cells ◽  
Surface Phenotype ◽  
V Region

Memory B cells isolated from human tonsils are characterized by an activated cell surface phenotype, localization to mucosal epithelium, expression of somatically mutated immunoglobulin (Ig) variable (V) region genes, and a preferential differentiation into plasma cells in vitro. In spleens of both humans and rodents, a subset of memory B cells is believed to reside in the marginal zone of the white pulp. Similar to tonsil-derived memory B cells, splenic marginal zone B cells can be distinguished from naive follicular B cells by a distinct cell surface phenotype and by the presence of somatic mutations in their Ig V region genes. Although differences exist between human naive and memory B cells, no cell surface molecules have been identified that positively identify all memory B cells. In this study, we have examined the expression of the receptor-type protein tyrosine phosphatase CD148 on human B cells. CD148+ B cells present in human spleen exhibited characteristics typical of memory B cells. These included an activated phenotype, localization to the marginal zone, the expression of somatically mutated Ig V region genes, and the preferential differentiation into plasma cells. In contrast, CD148− B cells appeared to be naive B cells due to localization to the mantle zone, the expression of surface antigens typical of unstimulated B cells, and the expression of unmutated Ig V region genes. Interestingly, CD148+ B cells also coexpressed CD27, whereas CD148− B cells were CD27−. These results identify CD148 and CD27 as markers which positively identify memory B cells present in human spleen. Thus, assessing expression of these molecules may be a convenient way to monitor the development of memory B cell responses in immunocompromised individuals or in vaccine trials.

scholarly journals Immunoglobulin Heavy Chain Variable Region Gene Replacement as a Mechanism for Receptor Revision in Rheumatoid Arthritis Synovial Tissue B Lymphocytes

2000 ◽  
Vol 192 (8) ◽  
pp. 1151-1164 ◽  
Author(s):  
Kenji Itoh ◽  
Eric Meffre ◽  
Emilia Albesiano ◽  
Andrew Farber ◽  
David Dines ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
B Cells ◽  
B Lymphocytes ◽  
Heavy Chain ◽  
Variable Region ◽  
Immunoglobulin Heavy Chain ◽  
Dna Breaks ◽  
Heavy Chain Variable Region ◽  
Vh Replacement ◽  
Synovial Tissues

Mature B cells can alter their antibody repertoires by several mechanisms, including immunoglobulin heavy chain variable region (VH) replacement. This process changes the antigen combining site by replacing a portion of the original VH/diversity/heavy chain joining region (VHDJH) rearrangement with a corresponding portion of a new VH segment. This exchange can involve cryptic heptamer-like sequences embedded in the coding regions of VH genes. While studying the B lymphocytes that expand in the synovial tissues of patients with rheumatoid arthritis (RA), clones with VHDJH variants that were apparently generated by VH replacement were identified with surprising frequency (∼8%). Examples of multiple independent VH replacement events occurring in distinct progeny clones were also identified. These secondary VH rearrangements were documented at both the cDNA and genomic DNA levels and involved several heptamer-like sequences at four distinct locations within VH (three sites in framework region 3 and one in complementarity determining region 2). The identification of blunt-ended double-stranded DNA breaks at the embedded heptamers and the demonstration of recombinase activating gene (RAG) expression suggested that these rearrangements could occur in the synovial tissues, presumably in pseudo-germinal centers, and that they could be mediated by RAG in a recognition signal sequence–specific manner. The presence of VH mutations in the clones that had undergone replacement indicated that these B cells were immunocompetent and could receive and respond to diversification signals. A relationship between these secondary VH gene rearrangements and the autoimmunity characteristic of RA should be considered.

scholarly journals Interaction and sequence diversity among T15 VH genes in CBA/J mice.

1988 ◽  
Vol 168 (4) ◽  
pp. 1339-1349 ◽  
Author(s):  
S E Ferguson ◽  
S Rudikoff ◽  
B A Osborne
Keyword(s):  
Heavy Chain ◽  
Sequence Variation ◽  
Variable Region ◽  
Gene Interaction ◽  
Time Frame ◽  
Gene Correction ◽  
Heavy Chain Variable Region ◽  
Vh Genes ◽  
Short Time ◽  
Variable Region Genes

Nucleotide sequences of the four genes composing the T15 heavy chain variable region (VH) family of the CBA/J mouse have been determined. Comparison of these sequences with their published BALB/c and C57BL/10 homologues reveals that nucleotide differences found between given alleles of two strains, i.e., CBA/J and BALB/c, are observed in other family members of the same strain. We suggest that these patterns of sequence variation are most readily explained by gene interaction (conversion). Additionally, the sequence of a CBA/J hybridoma, 6G6, proposed to have been generated by gene conversion, is directly encoded by the CBA/J V11 gene indicating that the putative conversion has occurred meiotically in the germline. These results are consistent with the premise that gene correction is occurring frequently among members of this family and that such processes may contribute significantly to the evolution of Ig variable region genes even in the relatively short time frame of inbred strain derivation.

scholarly journals Receptor Revision of Immunoglobulin Heavy Chain Variable Region Genes in Normal Human B Lymphocytes

2000 ◽  
Vol 191 (11) ◽  
pp. 1881-1894 ◽  
Author(s):  
Patrick C. Wilson ◽  
Kenneth Wilson ◽  
Yong-Jun Liu ◽  
Jacques Banchereau ◽  
Virginia Pascual ◽  
...  
Keyword(s):  
Heavy Chain ◽  
Clonal Selection ◽  
Variable Region ◽  
Cell Subpopulation ◽  
Lymphoid Tissues ◽  
Heavy Chain Variable Region ◽  
Clonal Selection Theory ◽  
Physiological Importance ◽  
Vh Gene ◽  
Vh Genes

Contrary to the general precepts of the clonal selection theory, several recent studies have provided evidence for the secondary rearrangement of immunoglobulin (Ig) genes in peripheral lymphoid tissues. These analyses typically used transgenic mouse models and have only detected secondary recombination of Ig light chain genes. Although Ig heavy chain variable region (VH) genes encode a substantial element of antibody combining site specificity, there is scant evidence for VH gene rearrangement in the periphery, leaving the physiological importance of peripheral recombination questionable. The extensive somatic mutations and clonality of the IgD+Strictly-IgM−CD38+ human tonsillar B cell subpopulation have now allowed detection of the first clear examples of receptor revision of human VH genes. The revised VDJ genes contain “hybrid” VH gene segments consisting of portions from two separate germline VH genes, a phenomenon previously only detected due to the pressures of a transgenic system.

scholarly journals Splenic lymphoma with villous lymphocytes involves B cells with extensively mutated Ig heavy chain variable region genes

Blood ◽  
1995 ◽  
Vol 85 (6) ◽  
pp. 1603-1607 ◽  
Author(s):  
D Zhu ◽  
DG Oscier ◽  
FK Stevenson
Keyword(s):  
B Cells ◽  
B Cell ◽  
Heavy Chain ◽  
Plasma Cells ◽  
Somatic Hypermutation ◽  
Variable Region ◽  
Low Grade ◽  
Cell Of Origin ◽  
Splenic Lymphoma ◽  
Vh Genes

Splenic lymphoma with villous lymphocytes (SLVL) is a recently defined subgroup of chronic B-cell lymphoproliferative diseases. The characteristic morphology of the tumor cells, together with phenotypic and cytogenetic findings, indicate that it is a distinct entity, but the nature of the cell or origin and its relationship to other low- grade lymphomas is unclear. For B-cell tumors, analysis of the variable region heavy chain (VH) genes used to encode the clonal Ig has shown marked differences between histologic categories, both in gene usage and extent of somatic mutation. An investigation of VH genes used in five typical cases of SLVL has shown somatic hypermutation from germline sequences in all cases, indicating that the cell of origin has been exposed to the hypermutation mechanism. However, no clonal heterogeneity was detectable, demonstrating that the tumor cell does not accumulate further mutations. These characteristics are similar to those found in mature postfollicular B cells, such as plasma cells. The distribution of mutations leading to replacement amino acids differed among the cases, with three of five cases showing clear evidence for antigen selection.

ZAP-70 directly enhances IgM signaling in chronic lymphocytic leukemia

Blood ◽  
2005 ◽  
Vol 105 (5) ◽  
pp. 2036-2041 ◽  
Author(s):  
Liguang Chen ◽  
John Apgar ◽  
Lang Huynh ◽  
Frank Dicker ◽  
Teresa Giago-McGahan ◽  
...  
Keyword(s):  
B Cells ◽  
Chronic Lymphocytic Leukemia ◽  
Heavy Chain ◽  
Variable Region ◽  
Adenovirus Vector ◽  
Lymphocytic Leukemia ◽  
Clinical Behavior ◽  
Heavy Chain Variable Region ◽  
Variable Region Genes ◽  
Aggressive Clinical Behavior

Abstract Chronic lymphocytic leukemia (CLL) B cells that express unmutated immunoglobulin heavy-chain variable region genes (IgVH) generally express ZAP-70, in contrast to normal B cells or most CLL cases with mutated IgVH. Following IgM ligation, ZAP-70+ CLL cells had significantly higher levels of phosphorylated p72Syk, BLNK, and phospholipase-Cγ (PLCγ) and had greater[Ca2+]i flux than did ZAP-70–negative CLL cases, including unusual ZAP-70–negative cases with unmutated IgVH. IgM ligation of ZAP-70–negative CLL B cells infected with an adenovirus vector encoding ZAP-70 induced significantly greater levels of phosphorylated p72Syk, BLNK, and PLCγ and had greater[Ca2+]i flux than did similarly stimulated, noninfected CLL cells or CLL cells infected with a control adenovirus vector. We conclude that expression of ZAP-70 in CLL allows for more effective IgM signaling in CLL B cells, a feature that could contribute to the relatively aggressive clinical behavior generally associated with CLL cells that express unmutated IgVH.

Characterization of Feline Immunoglobulin Heavy Chain Variable Region Genes for the Molecular Diagnosis of B-cell Neoplasia

2005 ◽  
Vol 42 (5) ◽  
pp. 596-607 ◽  
Author(s):  
J. A. Werner ◽  
J. C. Woo ◽  
W. Vernau ◽  
P. S. Graham ◽  
R. A. Grahn ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Heavy Chain ◽  
Variable Region ◽  
B Cell Lymphoma ◽  
Immunoglobulin Heavy Chain ◽  
Heteroduplex Analysis ◽  
Sequence Information ◽  
Heavy Chain Variable Region ◽  
Pcr Products

To develop a molecular-based assay so that the diagnosis of feline B-cell neoplasia can be facilitated, we have characterized 24 feline immunoglobulin heavy chain variable region ( IGH V) complementary DNA (cDNA) transcripts. Structural homology with rearranged human IGH V genes was found, and the sequence information was used to design a feline-specific polymerase chain reaction (PCR)-based assay to amplify the complementarity determining region 3 as a marker for B-cell clonality. Conserved primers derived from the second and third framework regions of V gene segments were used in conjunction with 2 sequence-specific primers and 1 degenerate primer derived from the J gene segments. Each PCR reaction was run in duplicate, and both native and denatured PCR products were evaluated using polyacrylamide gel electrophoresis. Formalin-fixed, paraffin-embedded (FFPE) tissue sections from cats with confirmed B-cell neoplasia (diffuse large B-cell lymphoma, plasmacytoma, and myeloma) were examined, and 15/22 (68.2%) cats produced results indicative of the presence of a monoclonal population of B cells. The evaluation of denatured PCR products (heteroduplex analysis) facilitated a more accurate interpretation in 3/15 (20%) cats. Pseudoclonality was a major reason for the failure to detect monoclonality. Poor DNA quality is a significant concern and was responsible for the removal of 2 cats from the study. Using this assay, FFPE normal feline lymphoid tissues and unfixed peripheral blood mononuclear cells were determined to be composed of polyclonal populations of B cells. This assay represents a useful adjunctive diagnostic tool for the diagnosis and investigation of feline B-cell lymphoproliferative disorders.

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