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F Tron

Publications and source records attributed to F Tron.

At least 55 records · Page 3Linked to original sources
PubMed1997

A complementarity-determining region peptide of an anti-desmosome autoantibody may interact with the desmosomal plaque through molecular mimicry with a cytoplasmic desmoglein 1 sequence.

The sera of patients with pemphigus, a group of autoimmune blistering skin diseases, contain autoantibodies directed against components of adhering junctions termed desmosomes. F12, a human monoclonal antibody derived from a pemphigus patient, recognizes an unknown polypeptide of the desmosomal and hemidesmosomal plaques. The third complementarity-determining region of the F12 heavy chain (VH-CDR3) was shown to share a four-amino-acid sequence (GSSG) with the intracellular domains of desmoglein 1 and bullous pemphigoid antigen 2 which interact with components of, respectively, the desmosomal and hemidesmosomal plaques. Computer modeling of F12 showed that the GSSG sequence protudes inside the antigen-combining site and thus might be involved in antigen interactions. The GSSG sequence is essential to F12 function, since a peptide containing the VH-CDR3 inhibited its binding to target antigens while VH-CDR3 peptides with specific modifications of the GSSG sequence did not. These data allow us to hypothesize that certain autoantibodies produced during the course of an autoimmune disease can behave as adhesion molecules, through the molecular mimicry of the motif involved in protein/protein adhesion, and to propose a new self-antigen binding mechanism for some autoantibodies.

Amino Acid Sequence↗
PubMed1997

Idiotypic analysis of anti-nucleosome monoclonal antibodies derived from lupus mice.

3F6 and 2E1 are anti-(H2A-H2B) monoclonal antibodies derived from a 12-month-old (NZBxNZW)F1 mouse that diverged from the same clonal precursor by somatic mutations. Rabbit anti-idiotypic antisera were prepared against these two monoclonal antibodies and used as probes to analyse the properties and expression of 3F6 and 2E1 idiotypes. Both idiotypes were conformational, distant from the antigen binding site and did not correlate with a VH- or VL-chain usage. 3F6 was preferentially bound by anti-3F6 idiotype but was weakly recognized by anti-2E1 idiotype suggesting, since 3F6 derives from 2E1, that 3F6 bore idiotypic determinants generated by somatic mutations. While none of the murine anti-DNA monoclonal antibodies tested expressed 2E1 or 3F6 idiotypes, 3F6 idiotype could be detected on approximately one-third of anti-(H2A-H2B) monoclonal antibodies derived from other lupus strains of mice, demonstrating the presence of cross-reactive idiotypes on autoantibodies directed against a nucleosome that could result from somatic mutations.

Animals↗
PubMed1997

Modeling of anti-nucleosome immunoglobulin Fv domains: analysis of electrostatic interactions.

Three-dimensional structural models of six murine anti-(H2A-H2B) monoclonal autoantibody variable fragments were built by comparative molecular modeling using the COMPOSER software. Analysis of the antibody combining sites is based on the hypothesis that ionic and/or electrostatic interactions predominate in antigen antibody binding, as suggested by the cationic nature of histones and the amino acid sequences of the antibody hypervariable regions. The study of the electrostatic potentials of their combining site surfaces, computed with the MOLCAD software, and the comparison with the electrostatic potentials of 13 selected control mAbs show the lack of a unique electrostatic pattern. One group of three mAbs expresses a strong and large electronegative area, supporting the hypothesis that ionic interactions predominate in antigen recognition. The second group, containing the other three mAbs, exhibits an alternation of electropositive and electronegative areas. All, however, present a localized electronegative area in the vicinity of H-CDR1 and H-CDR2 loops that is generated by the presence of at least one acidic residue. The model suggesting that the binding activity may depend on charged residues at the same site is reminiscent of what was previously reported in anti-DNA mAbs. In addition, the alternation of electropositive areas and electronegative areas in second group mAbs is also frequently observed in certain anti-DNA mAbs. These data argue for the existence of relationships between these two autoantibody populations and suggest that they share a common immunogenic particle formed by anionic and cationic components, such as a nucleosome.

Amino Acid Sequence↗
PubMed1997

Identification of a new antibody population directed against a desmosomal plaque antigen in pemphigus vulgaris and pemphigus foliaceus.

Pemphigus vulgaris and pemphigus foliaceus are characterized by autoantibodies directed against transmembrane glycoproteins of desmosomes. F12, a human monoclonal autoantibody that binds to the desmosomal plaque, recognizes a 180-190-kDa doublet when immunoblotted against bovine tongue epithelium. Because F12 was derived from the peripheral blood lymphocytes of a patient with pemphigus vulgaris, we looked for the presence of anti-180-190-kDa antibodies in pemphigus vulgaris and pemphigus foliaceus serum. By immunoblot analysis, a third of the pemphigus serum contained anti-180-190-kDa antibodies that belonged to IgG subclass 1 or 3, unlike those that recognized desmogleins 1 and 3 (IgG4). By immunoelectron microscopy analysis on human oral mucosa and human skin with mAb to human IgG3, pemphigus serum containing anti-180-190 kDa antibodies recognized desmosomal plaques. The presence of antibodies with F12 properties in pemphigus serum was further demonstrated by a rabbit anti-F12 idiotype antiserum that allowed detection of F12 idiotype in serum with anti-180-190-kDa antibodies. These results indicate that some pemphigus vulgaris and pemphigus foliaceus serums contain antibodies that react with both intra- and extracellular structures of desmosomes and further demonstrate the heterogeneity of the autoimmune response in both types of pemphigus.

Antibodies, Monoclonal↗
PubMed1997

In vivo and in vitro activation and expansion of gammadelta T cells during Listeria monocytogenes infection in humans.

Serial flow cytometry analyses of peripheral blood mononuclear cells obtained from 8 patients infected with Listeria monocytogenes showed a higher percentage (P < 0.01) of gammadelta T cells (median, 11.7; range, 3.7 to 35.3) than did 16 age-matched uninfected controls (1.7, 0.4 to 13). Most in vivo-expanded gammadelta T cells expressed the Vgamma9 and Vdelta2 gene products and displayed a memory phenotype (CD45RO[high]), and patients' gammadelta T cells expressed significantly more (P < 0.01) activation marker HLA-DR than did controls (19.8% [median] and 0.9 to 87.6% [range] versus 2.3% and 0 to 4.7%, respectively). When peripheral blood mononuclear cells from normal donors were cultured in vitro with heat-killed Listeria cells, analysis of CD25 and HLA-DR expression on gammadelta and alphabeta T cells indicated that a high percentage of gammadelta T cells was activated early compared to alphabeta T cells. In addition, depletion of gammadelta T cells before culture abrogated the early lymphocyte proliferative response induced by the pathogen. Taken together, these results argue for the involvement of gammadelta T cells during L. monocytogenes infection in humans.

Adult↗
PubMed1997

Relationship between the in vivo localization and the immunoblotting pattern of anti-basement membrane zone antibodies in patients with bullous pemphigoid.

OBJECTIVE: To compare the localization of anti-basement membrane zone (BMZ) antibodies bound in vivo with the antigenic specificities of circulating anti-BMZ antibodies in patients with bullous pemphigoid (BP). DESIGN: Comparison of the results of an examination of the skin specimens of the patients using direct immunoelectron microscopy and direct immunofluorescence on 1-mol/L sodium chloride-split skin with the results of an analysis of the corresponding serum samples using the immunoblot technique. SETTING: Immunodermatology department in a teaching hospital. PATIENTS: Thirty-six patients with typical BP and circulating anti-BMZ antibodies. RESULTS: Serum samples from 22 patients with BP indicated only BP antigen 1 in the results of immunoblot analysis. Using direct immunofluorescence, an analysis of the peribullous skin samples obtained from these 22 patients showed deposits of IgG exclusively located along the epidermal side of sodium chloride-split skin; the results of direct immunoelectron microscopic examination showed deposits of IgG located on the intracellular portion of hemidesmosomes in 18 (82%) of these 22 specimens, whereas 4 biopsy specimens had linear IgG deposits located both intracellularly and extracellularly along the keratinocyte plasma membrane. The results of immunoblot analysis of the serum samples from 5 patients with BP indicated BP antigen 2 alone; the results of direct immunoelectron microscopic examination of peribullous skin samples from these 5 patients showed linear intracellular and extracellular deposits along the keratinocyte membrane, corresponding to an epidermal fluorescence labeling pattern of peribullous sodium chloride-split skin in 2 patients and a combined (dermal and epidermal) pattern in 3 patients. CONCLUSION: The 2 different patterns of reactivity of anti-BMZ antibody deposits bound in vivo closely corresponded to the antigenic specificities indicated in the corresponding serum samples of the patients. These results are in accordance with those previously obtained in vitro and argue for identical binding profiles of circulating antibodies that are bound in vivo in BP.

Autoantibodies↗
PubMed1997

Autoantibody formation against a 190-kDa antigen of the desmosomal plaque in pemphigus foliaceus.

We report changes in the antigen recognition pattern of sera from two pemphigus foliaceus patients with a long-term follow-up. The patients' sera were analysed by immunoblotting using different antigenic sources: cultured human keratinocytes, bovine tongue epithelium and a recombinant protein corresponding to the C-terminal end of the 230-kDa bullous pemphigoid antigen. While initial serum samples reacted exclusively with the 160-kDa desmoglein 1, the later sera reacted both with desmoglein 1 and a 190-kDa antigen immunolocalized to the desmosomal plaque, previously demonstrated to be recognized by sera of some patients with paraneoplastic pemphigus. IgG subclass analysis further showed that antidesmoglein 1 antibodies were of IgG1 and/or IgG4 subclasses, while anti-190-kDa antibodies were IgG3. The patients were free of malignancy.

Aged↗
PubMed1997

[Coronary involvement in systemic lupus erythematosus].

BACKGROUND: Coronary artery disease is an uncommon event in lupus erythematosus. The mechanisms responsible for coronary occlusion are probably complex and intermixed. We report three patients with lupus erythematosus and antiphospholipid antibodies who had coronary artery disease diagnosed with coronary angiogram. OBSERVATION: Coronary artery disease occurred in three young patients aged from 21 to 35 years 3 to 11 years after the onset of lupus. They all had antiphospholipid antibodies. They had been treated with corticosteroids for 6 to 36 months. Two of them were smokers. Angiograms showed coronary occlusion two patients while the third one had probable myocardial microvasculopathy. The lupus was quiescent in all cases when coronary artery disease occurred. DISCUSSION: Antiphospholipid antibodies associated with smoking may be involved in the pathogenesis of coronary artery disease in these 3 patients.

Adrenal Cortex Hormones↗
PubMed1996

Structural properties and mutation patterns of anti-nucleosome monoclonal antibodies are similar to those of anti-DNA antibodies.

Four monoclonal antibodies (mAb) derived from an (NZB x NZW)F1 mouse bound to nucleosomes, total histones and to the H2A-H2B dimers but not to individual histones or DNA. Sequencing of their heavy (H)- and light (L)-chain variable region genes showed that they derived by somatic mutations from the same B cell precursor. The distribution of negatively and positively charged amino acids in the H-chain complementarity-determining regions was very similar to that observed not only in anti-H2A-H2B mAb derived from different lupus-prone mouse strains but also in anti-DNA mAb. Combined analysis of the mAb structures and their interactions with immobilized H2A-H2B dimer or total histones by plasmon resonance allowed us to assign the H-chain mutations a major role in the binding profiles of these anti-nucleosome mAb. Interestingly, four of the five H-chain mutations that distinguished mAb 3F6 from 2E1 generated negatively or positively charged amino acid residues, and two of them occurred at positions 56 and 76, which are frequently involved in the maturation process of anti-DNA antibodies. A modeling study of the 3F6 variable fragment (Fv) predicted that acidic residues occupy the cleft of the Ab combining site and have the potential to participate in electrostatic interactions. Thus, the demonstration that (NZB x NZW)F1-derived anti-H2A-H2B antibodies share certain structural features and mutation patterns with anti-DNA mAb suggest that common selection and maturation processes account for the production of these lupus-related autoantibodies.

Amino Acid Sequence↗
PubMed1996

Similarity of expression of activation markers and CD28 on gamma delta and alpha beta-receptor T cells in HIV infection.

During human immunodeficiency virus (HIV) infection, phenotypic analysis of circulating gamma delta+ T cells showed a downregulation of the CD28 surface antigen, as recently demonstrated for CD4+ and CD8+ alpha beta+ T cells. The downregulation of the CD28 molecule predominated on CD8+ gamma delta+ T cells. Moreover, an increased expression of CD38 and/or HLA-DR molecules was found on gamma delta T cells as reported for alpha beta T cells indicating that all categories of circulating T lymphocytes share similar phenotypic abnormalities in HIV-infected patients. These unique changes in the different T-cell subsets might be induced by sustained activation of the immune system or by the rapid turnover of T cells and argue for a global dysregulation of T lymphocytes during HIV infection.

ADP-ribosyl Cyclase↗
PubMed1996

Do naturally occurring autoantibodies participate in the constitution of the pathological B-cell repertoire in systemic lupus erythematosus?

Systemic lupus erythematosus (SLE) is the prototype of systemic autoimmune diseases. In both human and mouse SLE diseases, the autoimmune response targets a restricted set of autoantigens. Many of them are nucleic acids and proteins involved in the synthesis and processing of DNA or RNA, a characteristic which should be taken into consideration to elucidate the origins of non organ-specific autoantibodies. Several observations, in particular those obtained from experimental models of SLE induced in normal mice, suggest that the breakdown of B-cell tolerance occurs in the periphery. Herewith, we present data further supporting the proposition that SLE-associated autoantibodies originate from natural autoantibody-secreting B cells activated in the internal environment of lupus mice. Thus, one may hypothesize that certain clones of the expanded primary B-cell repertoire are selected to differentiate into harmful IgG autoantibody-secreting clones, thereby raising the question of the nature of immunogenic structures involved in SLE. Our analysis of the immunochemical and structural properties of anti-nucleosome and anti-myeoloperoxidase monoclonal antibodies derived from (NZB x NZW)F1 mice leads us to propose that complexes formed by the association of DNA and DNA-binding proteins and, more generally, by anionic molecules associated with proteins, possess a selective advantage over other autoantigens to induce the differentiation of certain B-cell clones and the very special profile of the SLE-autoimmune response. These DNA/DNA-protein complexes could also play a role in the activation of the T-cell compartment in SLE.

Animals↗
PubMed1996

Binding of autoantibodies is not restricted to desmosomes in pemphigus vulgaris: comparison of 14 cases of pemphigus vulgaris and 10 cases of pemphigus foliaceus studied by western immunoblot and immunoelectron microscopy.

Pemphigus vulgaris (PV) and pemphigus foliaceus (PF) are autoimmune blistering diseases characterized by a loss of cell-cell adhesion and by autoantibodies directed against epidermal cadherins. PF antigen has been established as desmoglein I which is located strictly on the desmosome, whereas the precise ultrastructural localization of PV antigen remains unclear and controversial to date. To further investigate this question, we compared the location of immune deposits in 14 patients with PV and 10 patients with PF by both direct and indirect immunoelectron microscopy (IEM). Inclusion criteria were based upon clinical features, histological level of cleavage and characterization of circulating antibodies by Western blot on epithelial bovine tongue extracts. IEM was performed on unfixed 0.7-mm slices of skin for the direct technique or on normal skin for the indirect technique using peroxidase labelling. In PF, by both direct and indirect IEM, immune deposits were located on the extracellular part of desmosomes (desmoglea) in all the samples studied. In PV, by both direct and indirect IEM, deposits were situated on the desmoglea and along large portions of the keratinocyte membrane without desmosomal structures in 15 of the 18 samples studied and only on the desmoglea in 3 samples. These results suggest that, in contrast to PF, the target antigen in PV is not always restricted to desmosomes. As various types of adherens junctions have been reported to mediate cell adhesion in the epidermis, the PV antigen could be a component of desmosomes and of other focal adhesions.

Adult↗
PubMed1995

[Vaccination immunology].

Vaccines induce the activation and differentiation of antigen specific-T and B lymphocytes, and the development of humoral and cellular effector mechanisms responsible for the destruction of pathogenic agents. The characteristics of the immune response depend on the nature of the antigen, the route of administration of the vaccine and the genotype of the vaccinated individual. Antigen recognition and B and T lymphocyte interactions take place in secondary lymphoid organs. Antigen-stimulated lymph nodes exhibit dramatic changes involving the lymphoid follicles where major events such as clonal selection, differentiation and maturation of B- and T-cell precursors occur. These events include various cellular and lymphokine signals termed cellular cooperation. Different effector mechanisms participate in antigen elimination.

Antigens↗