scholarly journals In situ studies of the primary immune response to (4-hydroxy-3-nitrophenyl)acetyl. III. The kinetics of V region mutation and selection in germinal center B cells.

1993 ◽  
Vol 178 (4) ◽  
pp. 1293-1307 ◽  
Author(s):  
J Jacob ◽  
J Przylepa ◽  
C Miller ◽  
G Kelsoe
Keyword(s):  
B Cells ◽  
Germinal Center ◽  
Somatic Hypermutation ◽  
Point Mutations ◽  
Variable Region ◽  
Germinal Centers ◽  
Primary Immune Response ◽  
Kinetics Of ◽  
Mutation And Selection ◽  
Germinal Center B Cells

In the murine spleen, germinal centers are the anatomic sites for antigen-driven hypermutation and selection of immunoglobulin (Ig) genes. To detail the kinetics of Ig mutation and selection, 178 VDJ sequences from 16 antigen-induced germinal centers were analyzed. Although germinal centers appeared by day 4, mutation was not observed in germinal center B cells until day 8 postimmunization; thereafter, point mutations favoring asymmetrical transversions accumulated until day 14. During this period, strong phenotypic selection on the mutant B lymphocytes was inferred from progressively biased distributions of mutations within the Ig variable region, the loss of crippling mutations, decreased relative clonal diversity, and increasingly restricted use of canonical gene segments. The period of most intense selection on germinal center B cell populations preceded significant levels of mutation and may represent a physiologically determined restriction on B cells permitted to enter the memory pathway. Noncanonical Ig genes recovered from germinal centers were mostly unmutated although they probably came from antigen-reactive cells. Together, these observations demonstrate that the germinal center microenvironment is rich and temporally complex but may not be constitutive for somatic hypermutation.

scholarly journals In situ studies of the primary immune response to (4-hydroxy-3-nitrophenyl)acetyl. II. A common clonal origin for periarteriolar lymphoid sheath-associated foci and germinal centers.

1992 ◽  
Vol 176 (3) ◽  
pp. 679-687 ◽  
Author(s):  
J Jacob ◽  
G Kelsoe
Keyword(s):  
B Cells ◽  
B Cell ◽  
Germinal Center ◽  
Somatic Hypermutation ◽  
Variable Region ◽  
Germinal Centers ◽  
Primary Immune Response ◽  
Cell Populations ◽  
Peanut Agglutinin ◽  
Clonal Origin

In the genetically restricted response that follows immunization with (4-hydroxy-3-nitrophenyl)acetyl coupled to protein carriers, two distinct populations of B cells are observed in the spleens of C57BL/6 mice. By 48 h postimmunization, foci of antigen-binding B cells appear along the periphery of the periarteriolar lymphoid sheaths. These foci expand to contain large numbers of antibody-forming cells that neither bind the lectin, peanut agglutinin, nor mutate the rearranged immunoglobulin variable region loci. Germinal centers containing peanut agglutinin-positive B cells can be observed by 96-120 h after immunization. Although specific for the immunizing hapten, these B cells do not produce substantial amounts of antibody, but are the population that undergoes somatic hypermutation and affinity-driven selection. Both focus and germinal center populations are pauciclonal, founded, on average, by three or fewer B lymphocytes. Despite the highly specialized roles of the focus (early antibody production) and germinal center (higher affinity memory cells) B cell populations, analysis of VH to D to JH joins in neighboring foci and germinal centers demonstrate that these B cell populations have a common clonal origin.

scholarly journals Germinal centers in human lymph nodes contain reactivated memory B cells

2007 ◽  
Vol 204 (11) ◽  
pp. 2655-2665 ◽  
Author(s):  
Richard J. Bende ◽  
Febe van Maldegem ◽  
Martijn Triesscheijn ◽  
Thera A.M. Wormhoudt ◽  
Richard Guijt ◽  
...  
Keyword(s):  
B Cells ◽  
Lymph Nodes ◽  
Germinal Center ◽  
Lymphoid Tissue ◽  
Somatic Hypermutation ◽  
Germinal Centers ◽  
Memory B Cells ◽  
Cell Clones ◽  
Clonal Origin ◽  
Successive Recall

To reveal migration trails of antigen-responsive B cells in lymphoid tissue, we analyzed immunoglobulin (Ig)M-VH and IgG-VH transcripts of germinal center (GC) samples microdissected from three reactive human lymph nodes. Single B cell clones were found in multiple GCs, one clone even in as many as 19 GCs. In several GCs, IgM and IgG variants of the same clonal origin were identified. The offspring of individual hypermutated IgG memory clones were traced in multiple GCs, indicating repeated engagement of memory B cells in GC reactions. These findings imply that recurring somatic hypermutation progressively drives the Ig repertoire of memory B cells to higher affinities and infer that transforming genetic hits in non-Ig genes during lymphomagenesis do not have to arise during a single GC passage, but can be collected during successive recall responses.

Nonimmunoglobulin Gene Hypermutation in Germinal Center B Cells

Blood ◽  
1999 ◽  
Vol 93 (7) ◽  
pp. 2167-2172 ◽  
Author(s):  
Huai-Zheng Peng ◽  
Ming-Qing Du ◽  
Athanasios Koulis ◽  
Antonella Aiello ◽  
Ahmet Dogan ◽  
...  
Keyword(s):  
B Cells ◽  
Germinal Center ◽  
Cell Lymphoma ◽  
Somatic Hypermutation ◽  
Mantle Zone ◽  
Germinal Center Reaction ◽  
Inherent Feature ◽  
Mantle Cell ◽  
Center Cell ◽  
Germinal Center B Cells

Somatic hypermutation is the most critical mechanism underlying the diversification of Ig genes. Although mutation occurs specifically in B cells during the germinal center reaction, it remains a matter of debate whether the mutation machinery also targets non-Ig genes. We have studied mutations in the 5′ noncoding region of the Bcl6 gene in different subtypes of lymphomas. We found frequent hypermutation in follicular lymphoma (25 of 59 = 42%) (germinal center cell origin) and mucosa-associated lymphoid tissue (MALT) lymphoma (19 of 45 = 42%) (postgerminal center), but only occasionally in mantle cell lymphoma (1 of 21 = 4.8%) (pregerminal center). Most mutations were outside the motifs potentially important for transcription, suggesting they were not important in lymphomagenesis but may, like Ig mutation, represent an inherent feature of the lymphoma precursor cells. Therefore, we investigated their normal cell counterparts microdissected from a reactive tonsil. Bcl6 mutation was found in 13 of 24 (54%) clones from the germinal centre but only in 1 of 24 (4%) clones from the naive B cells of the mantle zone. The frequency, distribution, and nature of these mutations were similar to those resulting from the Ig hypermutation process. The results show unequivocal evidence of non-Ig gene hypermutation in germinal center B cells and provide fresh insights into the process of hypermutation and lymphomagenesis.

scholarly journals WASp Is Crucial for the Unique Architecture of the Immunological Synapse in Germinal Center B-Cells

2021 ◽  
Vol 9 ◽  
Author(s):  
Yanan Li ◽  
Anshuman Bhanja ◽  
Arpita Upadhyaya ◽  
Xiaodong Zhao ◽  
Wenxia Song
Keyword(s):  
B Cells ◽  
B Cell ◽  
Lipid Bilayers ◽  
Germinal Center ◽  
Actin Polymerization ◽  
Immunological Synapse ◽  
Somatic Hypermutation ◽  
Affinity Maturation ◽  
Membrane Protrusions ◽  
Germinal Center B Cells

B-cells undergo somatic hypermutation and affinity maturation in germinal centers. Somatic hypermutated germinal center B-cells (GCBs) compete to engage with and capture antigens on follicular dendritic cells. Recent studies show that when encountering membrane antigens, GCBs generate actin-rich pod-like structures with B-cell receptor (BCR) microclusters to facilitate affinity discrimination. While deficiencies in actin regulators, including the Wiskott-Aldrich syndrome protein (WASp), cause B-cell affinity maturation defects, the mechanism by which actin regulates BCR signaling in GBCs is not fully understood. Using WASp knockout (WKO) mice that express Lifeact-GFP and live-cell total internal reflection fluorescence imaging, this study examined the role of WASp-mediated branched actin polymerization in the GCB immunological synapse. After rapid spreading on antigen-coated planar lipid bilayers, GCBs formed microclusters of phosphorylated BCRs and proximal signaling molecules at the center and the outer edge of the contact zone. The centralized signaling clusters localized at actin-rich GCB membrane protrusions. WKO reduced the centralized micro-signaling clusters by decreasing the number and stability of F-actin foci supporting GCB membrane protrusions. The actin structures that support the spreading membrane also appeared less frequently and regularly in WKO than in WT GCBs, which led to reductions in both the level and rate of GCB spreading and antigen gathering. Our results reveal essential roles for WASp in the generation and maintenance of unique structures for GCB immunological synapses.

scholarly journals Human germinal center B cells express the apoptosis-inducing genes Fas, c-myc, P53, and Bax but not the survival gene bcl-2.

1996 ◽  
Vol 183 (3) ◽  
pp. 971-977 ◽  
Author(s):  
H Martinez-Valdez ◽  
C Guret ◽  
O de Bouteiller ◽  
I Fugier ◽  
J Banchereau ◽  
...  
Keyword(s):  
Cell Cycle ◽  
B Cells ◽  
B Cell ◽  
Germinal Center ◽  
Somatic Hypermutation ◽  
Cell Subset ◽  
Variable Region ◽  
Negative Regulator ◽  
Memory B Cell ◽  
Survival Gene

During T cell-dependent antibody responses, B cells within germinal centers (GC) alter the affinity of their antigen receptor by introducing somatic mutations into variable region of immunoglobulin (IgV) genes. During this process, GC B cells are destined to die unless positively selected by antigens and CD40-ligand. To understand survival/death control of germinal center B cell, the expression of four apoptosis-inducing genes, Fas, c-myc, Bax, and P53, together with the survival gene bcl-2, has been analyzed herein among purified tonsillar naive, GC, and memory B cells. IgD+CD38- naive B cells were separated into CD23- (mature B cell [Bm]1) subset and CD23+ (Bm2), IgD-CD38+ GC B cells were separated into subsets of CD77+ centroblasts (Bm3) and CD77- centrocytes (Bm4), whereas IgD-CD38- cells represented the Bm5 memory B cell subset. Sequence analysis of IgV region genes indicated that somatic hypermutation was triggered in the Bm3 centroblast subset. Here we show that bcl-2 is only detectable with naive (Bm1 and 2) and memory B cell (Bm5) subsets, whereas all four apoptosis-inducing genes were most significantly expressed within GC B cells. Fas was equally expressed in Bm3 centroblasts and Bm4 centrocytes, whereas Bax was most significantly expressed in Bm4 centrocytes. c-myc, a positive regulator of cell cycle, was most significantly expressed in proliferating Bm3 centroblasts, whereas P53, a negative regulator of cell cycle, was most signficantly expressed in nonproliferating Bm4 centrocytes. The present results indicate that the survival/death of GC B cells are regulated by the up- and downregulation of multiple genes, among which the expression of c-myc and P53 in the absence of bcl-2 may prime the proliferating Bm3 centroblasts and nonproliferating Bm4 centrocytes to apoptosis.

miRNA Profiling of B Cell Subsets: Specific miRNA Profile for Germinal Center B Cells with a Marked Variation Between Centroblast and Centrocytes.

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 1459-1459
Author(s):  
Lu Ping Tan ◽  
Miao Wang ◽  
Jan-Lukas Robertus ◽  
Rikst Nynke Schakel ◽  
Johan H Gibcus ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Germinal Center ◽  
Germinal Centers ◽  
Memory B Cells ◽  
Mirna Profile ◽  
Mantle Zone ◽  
Tissue Sections ◽  
Germinal Center B Cell ◽  
Germinal Center B Cells

Abstract MiRNAs are a new class of small RNAs, of 19–23 nucleotides that were discovered less than two decades ago. These tiny RNAs can negatively regulate genes at the post-transcriptional level by either triggering translational repression or direct cleavage of mRNAs. It has become evident that miRNAs are involved in hematopoiesis and that the aberrant expression of miRNAs may give rise to hematopoietic malignancies. The aim of our study was to characterize the miRNA profile of naïve, germinal center and memory B cells sorted from tonsils and review expression of selected miRNAs in tonsils and in B cell malignancies by miRNA in situ hybridization (ISH). Quantitative (q)RT-PCR profiling revealed that several miRNAs were elevated in germinal center B cells, including miR-17–5p, miR-106a and miR-181b. miR-150 was one of the most abundant miRNAs in all subsets, but the expression level was more than 10 fold lower in germinal center B cell as compared to the other two subsets. MiRNA ISH on tonsillar tissue sections confirmed findings from the profiling work, and at the same time depicted differences in staining intensities within germinal centers. According to miRNA ISH, expression levels of miR-17-5p, miR-106a, and miR-181b were indeed higher in germinal center B cells as compared to naïve and memory B cells in the mantle zone. Surprisingly, we also observed gradual decrease of miR-17-5p, miR-106a, and miR-181b staining from dark to light zone in the germinal centers. Moreover, miRNA ISH with a probe for miR-150 demonstrated an interesting staining pattern in lymph node tissue sections. Naïve and memory B cells located in the mantle zone showed a higher miR-150 expression as compared to most of the cells in the germinal centers. However, within the germinal centers a minority of cells showed a much stronger cytoplasmic staining in part of the blasts located specifically in the dark zone. This indicated that part of the centroblasts have a high expression level of miR-150. The level of miR-150 was surprisingly low in 22 B cell lymphoma cell lines, irrespective of germinal center or non germinal center B cell origin. This seemingly negative association of miR-150 with proliferation suggests a role in B cell growth/death. We observed an inverse expression pattern of miR-150 and Survivin in the germinal centers by miRNA ISH and immunohistochemistry. Moreover, induction of miR-150 using synthetic mature miR-150 duplex resulted in reduced Survivin expression levels. Our results suggested that aside the experimentally proven target c-Myb, Survivin may also be regulated by miR-150. In conclusion, we have revealed a unique miRNA profile of naïve, germinal center and memory B cells sorted from normal tonsils and the results were confirmed by miRNA ISH. Within the germinal centers a marked difference was observed between the light zone and the dark zone.

scholarly journals Integrity of immunoglobulin variable regions is supported by GANP during AID-induced somatic hypermutation in germinal center B cells

2017 ◽  
Vol 29 (5) ◽  
pp. 211-220 ◽  
Author(s):  
Mohammed Mansour Abbas Eid ◽  
Mayuko Shimoda ◽  
Shailendra Kumar Singh ◽  
Sarah Ameen Almofty ◽  
Phuong Pham ◽  
...  
Keyword(s):  
B Cells ◽  
Germinal Center ◽  
Somatic Hypermutation ◽  
Variable Regions ◽  
Germinal Center B Cells

scholarly journals Relative contribution of T and B cells to hypermutation and selection of the antibody repertoire in germinal centers of aged mice.

1996 ◽  
Vol 183 (3) ◽  
pp. 959-970 ◽  
Author(s):  
X Yang ◽  
J Stedra ◽  
J Cerny
Keyword(s):  
T Cells ◽  
B Cells ◽  
Somatic Hypermutation ◽  
Variable Region ◽  
Germinal Centers ◽  
Antibody Repertoire ◽  
Gene Repertoire ◽  
Aged Mice ◽  
Relative Contribution ◽  
Adult Mice

The immune system of aged individuals often produces antibodies that have lower affinity and are less protective than antibodies from young individuals. Recent studies in mice suggested that antibodies produced by old individuals may be encoded by distinct immunoglobulin (Ig) genes and that the somatic hypermutation process in these individuals is compromised. The present study employed Ighb scid mice reconstituted with normal lymphocytes from young (2-3-mo-old) and aged (20-25-mo-old) donors and immunized with a protein conjugate of the hapten (4-hydroxy-3-nitrophenyl)acetyl (NP) to determine whether the molecular changes in antibody repertoire reflect senescence in the B cells or whether they are mediated by the aging helper T lymphocytes. The NP-reactive B cells from splenic germinal centers (GC) were recovered by microdissection of frozen tissue sections and their rearranged Ig heavy chain variable region (VH) genes of the V186.2/V3 families were sequenced. It was found that the VH gene repertoire of the GC B cells was strongly influenced by the source of the CD4+ T cells. When T cells were donated by young mice, the anti-NP response in GC was dominated by the canonical V186.2 gene, even if the responder B cells came from aged donors. However, when the mice were reconstituted with T cells from aged donors, the expression of the V186.2 gene by young B cells was diminished and the response was dominated by the C1H4 gene, another member of the V186.2/V3 family. In contrast, the somatic hypermutation process in the GC B cells followed a different pattern. The mutation frequencies in the animals that were reconstituted with both B and T cells from young donors (1/50 to 1/150 bp) were comparable to the frequencies previously reported for NP-immunized intact young/adult mice. However, when either lymphocyte subset was donated by the aged mice, the mutation frequencies declined. Thus, mice reconstituted with T cells from the aged and B cells from the young had severely compromised mutational mechanism. Likewise, the recipients of aged B and young T cells had diminished mutations even though the repertoire of their anti-NP response was dominated by the canonical V186.2 gene. It appears that the change in germine-encoded repertoire and the decrease of somatic hypermutation represent distinct mechanisms of immunosenescence and that the aging of helper T cells plays a pivotal role in both of these processes.

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