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Biomedical subjects

C Berek

Publications and source records attributed to C Berek.

At least 19 recordsLinked to original sources
PubMed1999

Plasma cell development in synovial germinal centers in patients with rheumatoid and reactive arthritis.

Plasma cells are found surrounding the inflammatory infiltrates of macrophages, T, and B cells in the synovial tissue of patients with rheumatoid and reactive arthritis. This characteristic arrangement suggests that in the synovial tissue CD20+ B cells differentiate into plasma cells. To examine clonal relationships, we have used micromanipulation to separately isolate CD20+ B cells and plasma cells from single infiltrates. DNA was extracted, and from both populations the VH/VL gene repertoires was determined. The data show that in the inflamed synovial tissue activated B cells are clonally expanded. During proliferation in the network of follicular dendritic cells, V gene variants are generated by the hypermutation mechanism. Surprisingly, we do not find identical rearrangements between CD20+ B cells and plasma cells. Nevertheless, the finding of clonally related plasma cells within single infiltrates suggests that these cells underwent terminal differentiation in the synovial tissue. These results indicate that B cell differentiation in the synovial tissue is a dynamic process. Whereas CD20+ B cells may turnover rapidly, plasma cells may well be long lived and thus accumulate in the synovial tissue. The analysis of individual B cells recovered from synovial tissue opens a new way to determine the specificity of those cells that take part in the local immune reaction. This will provide new insights into the pathogenesis of chronic inflammatory diseases like rheumatoid or reactive arthritis.

Adolescent↗
PubMed1999

Molecular analysis of rheumatoid factor (RF)-negative B cell hybridomas from rheumatoid synovial tissue: evidence for an antigen-induced stimulation with selection of high mutated IgVH and low mutated IgVL/lambda genes.

The mutational pattern of IgVH and IgVL genes from synovial tissue B cell hybridomas (n = 8) of patients (n = 4) with rheumatoid arthritis (RA) was analysed, which had been produced by the electrofusion technique without prior in vitro stimulation. The molecular data were correlated with immunohistopathological data and parameters of local disease activity. The IgVH genes of the B cell hybridomas belonged to the VH3 family (DP42; DP47, n = 2; DP53), the VH1 family (DP75), the VH4 family (DP71) and the VH5 family (DP73); 7/7 IgVH genes showed somatic mutations, the R/S ratio (CDR) was > 3 in 4/7 IgVH genes and the mean R/S ratio of all IgVH genes was 9.3 (CDR) and 1.0 (FR), suggesting an antigen-dependent selection. The IgVL/lambda genes belonged to the Vlambda1 family (DPL2, DPL5, DPL8nf), the Vlambda2 family (DPL11, n = 2) and to the Vlambda6 family (IGLV6S1); 6/6 IgVL genes showed somatic mutations, the R/S ratio (CDR) was > 3 in 3/6 IgVL genes and the mean R/S ratio of all IgVL was 3.0 (CDR) and 2.3 (FR), suggesting an antigen-dependent selection. The synovial tissue exhibited germinal centres in the follicles (3/4), with the unique distribution of Ki-M4+ follicular dendritic cells and Ki-67+ proliferating cells and a dominance of IgA+ plasma cells (3/3). All patients were positive for RF in serum and exhibited severe local symptoms (swelling 4/4; warmth 4/4; effusion 2/4), whereas the hybridomas were negative for RF. Since B cell hybridomas showed hypermutation and affinity selection for IgVH and IgVL/lambda genes and the patients exhibited severe local symptoms with germinal centres in synovial tissue, this study indicates that an antigen-driven process is behind the B cell expansion in the synovial tissue of clinically affected joints. These mutated B hybridomas were negative for RF, thus suggesting that antigens different from RF are also involved in the local B cell expansion and in the chronic synovitis of RA.

Aged↗
PubMed1998

Antigen-driven clonal proliferation of B cells within the target tissue of an autoimmune disease. The salivary glands of patients with Sjögren's syndrome.

Structures resembling germinal centers are seen in the salivary glands of patients with Sjögren's syndrome, but it is not known whether the microenvironment of these cell clusters is sufficient for the induction of a germinal center response. Therefore, we cloned and sequenced rearranged Ig V genes expressed by B cells isolated from sections of labial salivary gland biopsies from two Sjögren's syndrome patients. Rearranged V genes from B cells within one cell cluster were polyclonal and most had few somatic mutations. Two adjacent clusters from another patient each contained one dominant B cell clone expressing hypermutated V genes. None of the rearranged V genes was found in both clusters, suggesting that cells are unable to migrate out into the surrounding tissue and seed new clusters. The ratios of replacement to silent mutations in the framework and complementarity determining regions suggest antigen selection of high-affinity mutants. These results show that an antigen-driven, germinal center-type B cell response is taking place within the salivary glands of Sjögren's syndrome patients. In view of the recent demonstration of a germinal center response within the rheumatoid synovial membrane and the existence of similar structures in the target tissues of other autoimmune diseases, we propose that germinal center- type responses can be induced in the nonlymphoid target tissues of a variety of autoimmune diseases.

Antigens↗
PubMed1998

Overexpanded B cell clone mediating leukemic arthritis by abundant secretion of interleukin-1beta: a case report.

The role of cytokines in leukemic arthritis is unknown. The presentation of a patient with B cell chronic lymphocytic leukemia and destructive arthritis of the wrist joints prompted us to study the synovial cytokine pattern by immunohistologic analysis. In addition, rearranged V(H) and V(L) immunoglobulin genes were sequenced to assess B cell clonality. Heavy infiltrations of CD20+ cells with lambda light chain restriction were found in the synovial tissue. Sequencing demonstrated overexpansion of a single B cell clone (DP58/D/J(H)4b and IGLV3S2/Jlambda2-Jlambda3 for V(H) and V(L), respectively) in the peripheral blood. Identical V(H) and V(L) rearrangements were found in the synovial infiltrates. Somatic mutations were found in both the peripheral blood and the synovial clone. Immunohistologic study revealed the presence of abundant interleukin-1beta (IL-1beta) and, to a lesser degree, tumor necrosis factor beta (TNFbeta) (lymphotoxin). In contrast, TNFalpha, interferon-gamma, IL-4, IL-6, and IL-10 were rarely found in the synovial infiltrates. Therefore, IL-1beta secreted in great amounts by leukemic B cells appears to be the major cytokine that mediates joint destruction in leukemic arthritis.

Amino Acid Sequence↗
PubMed1998

The dynamic structure of the germinal center.

Analysis of germinal centers (GCs) in chronically inflamed human tonsils has led to the dogma that GCs contain two compartments with separate functions: a dark zone where B cells proliferate and hypermutate; and a light zone where selection and differentiation occur. However, here Stephanie Camacho and colleagues discuss immunohistological analysis of splenic GCs arising de novo that reveal a more plastic structure.

Animals↗
PubMed1998

A novel monospecific IgG2/lambda-autoantibody with specificity for a mitochondrial antigen: evidence for an antigen-driven pathogenetic B-cell response in rheumatoid synovial tissue, induced by tissue alteration.

To elucidate the pathogenic role of synovial B cells in rheumatoid arthritis (RA), nine human IgG/lambda-secreting B-cell hybridomas from rheumatoid synovial tissue of a patient with definite RA were screened by enzyme-linked immunosorbent assay and indirect immunofluorescence on tissue cryosections for detection of antibodies against autoantigens. One IgG2/lambda monoclonal antibody (mAb) from the B-cell hybridoma ELG211/15/63 (= hybr63) exhibited intense immunofluorescence reactivity in the cytoplasm of chondrocytes and epithelial cells of the gastrointestinal tract, especially in parietal cells of gastric mucosa (human and mouse tissue), representing a mitochondrial pattern. This result was confirmed by morphometric analysis of immunoelectron microscopy data, exhibiting a significantly higher labeling density in mitochondria (p < or = 0.001) than in the cytoplasmic background, with predominant staining in the inner mitochondrial membrane and mitochondrial matrix (p < or = 0.05). Immunoblotting experiments carried out with gastric mucosa, and a mitochondrial protein preparation revealed two major proteins of 38 and 50 kd under reducing conditions. The analysis of the IgV(H) genes from this B-cell hybridoma showed highest homology to the human germline gene DP53 (96%). The IgV(L) region gave highest homology to the human germline gene DP5 (93%). In the complementarity-determining regions, residues of the H- and L-chain variable regions replacement mutations only indicated that this B-cell clone had been antigen-selected for its affinity (ratio of replacement to silent mutations: > or = 7). To analyze the in vivo expansion of the B-cell clone, primers specific for the V(H) to D to J(H) rearrangement of this B-cell hybridoma were used. Specific amplifications could be detected within part of the synovial tissue but not within the cells of the synovial fluid and peripheral blood of the patient. The ability of the IgG2/lambda mAb to induce an inflammatory reaction was tested by intraperitoneal application in severe combined immunodeficiency (SCID) mice, which resulted in an inflammatory, predominantly granulocytic infiltration of the peritoneum. Consequently, intrasynovial cell death or cartilage destruction seems to be a possible source of liberation of mitochondrial antigens, inducing a local, antigen-driven IgG2/lambda B-cell response with the ability to induce an inflammatory reaction. These data suggest that tissue destruction may serve as a source of arthritogenic antigens that perpetuate and amplify the local pernicious inflammatory process in RA synovialitis.

Amino Acid Sequence↗
PubMed1997

B-cell activation and development within chronically inflamed synovium in rheumatoid and reactive arthritis.

In autoimmune diseases, B cells often accumulate in the affected tissue. In patients with rheumatoid arthritis or reactive arthritis, germinal center-like structures may develop in the inflamed synovial tissue. B cells from these structures were isolated and their V-gene repertoire determined. The majority of synovial B cells are long-term memory cells and thus are part of the chronic inflammatory reaction. In the synovium a micro-environment is built up which allows the activation of naive and memory B cells and the diversification of their V-gene repertoire. The analysis of plasma cells suggests that these cells are long lived and hence accumulate in the synovial tissue under chronic activation.

Arthritis, Reactive↗
PubMed1997

Antigen-dependent B cell differentiation in the synovial tissue of a patient with reactive arthritis.

BACKGROUND: Reactive arthritis (ReA) can develop as a consequence of a bacterial infection with organisms such as Chlamydia trachomata, Shigella flexneri, or Yersinia enterocolitica. Although the mechanism underlying the induction of a chronic synovitis is unknown, the expression of HLA-B27 seems to play a crucial role in the etiology of the disease. Bacterial antigens induce a humoral immune response, but little is know about the impact of B cells on the inflammatory processes developing in the synovial membrane. MATERIALS AND METHODS: Cryostat sections were prepared from the synovial tissue (ST) of patients with ReA and stained with antibodies specific for T, B, and follicular dendritic cells. Lymphoid infiltrates were directly isolated by microdisection and DNA was prepared from them. The rearranged V genes were amplified by polymerase chain reaction (PCR), cloned, and sequenced. RESULTS: Histological staining showed that germinal, center-like structures develop in the ST of patients with ReA. B cells with a heterogenous repertoire were isolated from these lymphoid infiltrates. The majority of V regions carried somatic mutations indicating that sequences are derived from memory B cells. Genealogical trees demonstrate clonal expansion and diversification of the B cell repertoire in the ST. CONCLUSIONS: The finding of local V-region diversification suggests that in the ST of patients with ReA, an antigen-driven, T cell-dependent differentiation of B cells occurs. This local B cell response may contribute to the progress of the disease. Whether B cells are specific for the bacteria inducing the synovitis or for self-determinants present in the ST remains to be determined.

Adult↗
PubMed1996

Differentiation of B cells in the nonlymphoid tissue of the synovial membrane of patients with rheumatoid arthritis.

In patients with rheumatoid arthritis the synovial membrane of the affected joint is infiltrated with lymphoid cells which may be arranged in structures resembling germinal centers. We have directly isolated such infiltrates to determine whether B-cell clones within them are selected and expanded in a process analogous to that which normally takes place in the germinal centers in secondary lymphoid organs. The data suggest that an antigen-driven process leads to the accumulation of B cells in the synovial membrane. The finding of identical sequences in consecutive sections suggests that under conditions of chronic stimulation, memory B cells may enter a stage of differentiation in which they proliferate without further accumulation of somatic mutations. Further we see intraclonal diversity which underlines the germinal center-like character of these infiltrates and demonstrates that a microenvironment is built up in this nonlymphoid tissue which supports antigen-dependent differentiation of B cells. This is the first demonstration, to our knowledge, of a germinal center-like reaction outside lymphoid tissue.

Adult↗
PubMed1996

Correlation between immune maturation and idiotypic network recognition.

The maturation of T-dependent humoral immune responses is mediated by somatic mutations. Antigen selection is one mechanism for the activation of B cell clones which express antibodies with progressively increased affinity and which are derived as somatic variants from germ-line-encoded genes. However, the emergence of B cell clones secreting rather low-affinity antibodies and the shift to alternative germ-line V region gene combinations during secondary and tertiary responses cannot be explained by antigen selection. It has been considered that idiotypic suppression may favor this clonal shift. Such an involvement would require that idiotypic recognition in the syngeneic host must be highly restricted to private idiotopes of each clone sequentially activated during immune maturation. To test this possibility, we produced 19 syngeneic anti-idiotypic antibodies to the germ-line-encoded major Ox1 idiotype (IgM-IdOx1 H11.5) of the anti-2-phenyl-oxazolone (phOx) immune response in BALB/c mice. The fine specificity of these anti-IdOx1 was tested with a set of anti-phOx monoclonal antibodies, representing the first steps of maturation. About half of the anti-IdOx1 showed almost no reactivity with the IdOx1 after the switch to IgG and none of the anti-IdOx1 reacted with anti-phOx antibodies which carried a glycine or histidine instead of arginine as the middle amino acid of the D region. These observations suggest a strong correlation between immune maturation and the idiotypic network. A model is presented in which idiotypic suppression may function as a driving force for diversification and maturation of the antigen-induced immune response.

Animals↗
PubMed1996

[Intra-articular B-cells in the pathogenesis of rheumatoid arthritis].

B-cells of the rheumatoid synovial tissue are constant and in some cases dominant elements of the inflammatory infiltrate and are located near to the site of tissue destruction. The pattern of B-cell distribution, the pattern and the relationship to the corresponding antigen presenting cells (follicular dendritical reticulum cells; FDC's) shows a great variation: B cells exhibit a follicular organisation forming secondary follicles, follicle like patterns with irregular formed FDC's networks and a diffuse pattern of and isolated FDC's. Molecular analysis of immunoglobulin genes from synovial B-cell clones and synovial tissue demonstrates the occurrence of immunoglobulin gene hypermutation as well as germline configuration. The FDC formations in the synovial tissue may therefore serve as an environment for B-cell maturation which is involved in the generation of autoantibodies. An autoantibody may be only defined as "pathogenic" if the antibody fulfills the Witebsky-Rose-Koch criteria for classical autoimmune disease: definition of the autoantibody, induction of the disease by transfer of the autoantibody and isolation of the autoantibody from the disease specific lesion. B-cells of rheumatoid synovial tissue show specificity for FcIgG, collagen 2, sDNA, tetanus toxoid, mitochondrial antigens (M2) and bacterial HSP's and the contribution of these antibodies to the pathogenesis of RA are still hypothetic. Antibody with specificity for bacterial HSP's which have arose during contact with an infectious agent and may due to crossreactivity with eukaryotic HSP of synovial tissue perpetuate the local inflammatory process. The characteristic pattern, the localisation within the area of tissue destruction and the exclusive function of B-cells to recognize conformation dependent antigens suggests a central role of B-cells in the inflammatory process. The analyzation of the synovial tissue B-cell therefore will help to characterise antigens which are responsible for the pathogenesis of RA.

Antibody Specificity↗
PubMed1994

Development of antibody diversity in single germinal centers: selective expansion of high-affinity variants.

In a T cell-dependent immune response the microenvironment of the germinal center plays a crucial role in the affinity maturation of the antigen-specific, immunoglobulins. In order to look at the development of antibody diversity we have isolated single germinal centers and sequenced light chains characteristic of 2-phenyl-oxazolone (phOx)-specific antibodies. Fourteen days after immunization we can demonstrate various stages of intraclonal diversity. There are germinal centers where B cells are practically unmutated, suggesting that in these cases a substantial clonal expansion has taken place prior to the activation of the hypermutation mechanism. In other germinal centers, sequences with a low number of randomly distributed somatic mutations were observed, indicating that these changes have been introduced recently and/or that they fail to generate high-affinity variants and hence provide no basis for affinity selection. Finally, germinal centers are found in which practically all sequences carry the amino acid substitutions characteristic of the high affinity phOx antibodies. In these latter cases the high-affinity variants have been preferentially expanded. We conclude that affinity selection is a process that operates right from the beginning of germinal center development. Those B cells with a relative high affinity for the antigen gain a proliferative advantage over other cells and will dominate the response and these are the cells which will be selected to differentiate into memory cells.

Amino Acid Sequence↗
PubMed1994

Maternal immunization modulates the primary immune response to 2-phenyl-oxazolone in BALB/c mice.

The development of the antibody repertoire in newborn mice is greatly influenced by idiotype network interactions. It has been demonstrated that anti-idiotypic antibodies either directly injected or transferred from the mother may alter the repertoire for life. For an elucidation of the underlying mechanisms we have analyzed the primary immune response to 2-phenyl-5-oxazolone (phOx) coupled to chicken serum albumin (CSA) in BALB/c mice after complete disappearance of maternal antibodies which originated from different stages of affinity maturation. Depending on the serum titers of the mothers after primary (1 degree mo), secondary (2 degrees mo) or tertiary (3 degrees mo) immunization, maternal anti-phOx IgG persisted in F1 mice for up to 9 months. In addition, F1 mice born to 2 degrees mo developed--even without immunization--an anti-phOx IgM titer which reached levels similar to an antigen-induced primary response. An enhancement of the early primary anti-phOx as well as anti-CSA response was seen in F1 mice born from 1 degree mo, whereas the response was delayed when born to 2 degrees mo and 3 degrees mo. The antibody titers in the latter group of mice remained at a lower level for 3 months. In contrast, mice of the F2 generation which received a smaller amount of the same collection of maternal antibodies as F1 mice from 3 degrees mo exhibited a quite different primary response: (i) They showed an earlier onset in their anti-CSA response. (ii) Whereas normally a plateau in antibody titer was reached by the 4th weak after immunization, in 55% of the F2 mice a prolonged increase of the anti-phOx and anti-CSA antibody titers was observed. At 12 weeks after antigenic challenge, titers reached plateau levels of 6 x 10(5) which were never before seen in a primary phOx or CSA response. Thus, depending on its own immunological experience, the maternal immune system induces a state of memory in the offspring which results in a faster and/or enhanced immune response in the F1 and F2 [corrected] generations.

Animals↗
PubMed1993

The maturation of the immune response.

In a T-cell dependent immune response, the repertoire of antigen-activated B cells is diversified by a hypermutation mechanism. Only high-affinity variants are selected into the pool of memory cells. This maturation process takes place in a special micro-environment, the germinal centre. Here, Claudia Berek and Mike Ziegner discuss the mechanisms underlying these processes.

Animals↗
PubMed1993

Somatic mutation and memory.

The germinal center plays a crucial role in the development of the memory B cell. The repertoire of the antigen-specific B cell is shaped in this microenvironment. Self-specific B cells escaping normal regulation may develop into high affinity pathogenic Ig-producing cells.

Animals↗