Biomedical subjects

M Viguier

Publications and source records attributed to M Viguier.

32 records · Page 2Linked to original sources

PubMed1998

Detection of Aspergillus galactomannan: comparison of an enzyme-linked immunoassay and a europium-linked time-resolved fluoroimmunoassay.

With a view to improving the sensitivity of serological detection of Aspergillus galactomannan (GM), a europium-linked time-resolved fluoroimmunoassay was developed. This method was compared to an enzyme-linked immunosorbent assay using a peroxidase-conjugated detector antibody. No increase in the sensitivity of the detection of GM standards was seen with the europium-based fluoroimmunoassay.

Antigens, Fungal↗

PubMed1997

In vivo T helper cell response to retro-inverso peptidomimetics.

Peptide analogues containing reversed peptide bonds between each residue along the peptide sequence (retro-inverso modification) have been analyzed for their antigenic and in vivo immunogenic properties in the MHC II and Th cell response context. Two antigenic peptides were selected for this study, namely peptide 103-115 of poliovirus VP1, which is involved in the production of Abs that neutralize the infectivity of the virus, and peptide 435-446 from the third constant region of mouse heavy chain IgG2a allopeptide gamma 2ab, which mimics a corneal Ag implicated in autoimmune keratitis. In a competition assay performed in vitro using reference hybridomas of known MHC class II restriction, both retro-inverso analogues bound (although more weakly in our test) to I-Ad and/or I-Ed class II molecules. However, in both cases, this lower affinity was apparently largely compensated in vivo, as a T cell response (with IL-2 secretion), equivalent to that obtained with the wild-type peptides, was observed following immunization of BALB/c mice with the retro-inverso analogues. Moreover, these T cells proliferated and produced IL-2 in response to the cognate peptides. It is concluded that the T cell receptors of T cells primed in vivo with the retro-inverso analogues readily cross-react with parent and retro-inverso analogue-MHC complexes. The approach of using pseudopeptides containing changes involving the backbone, and not the orientation of side chains, may thus be promising to design potent immunogens for class II-restricted T cells.

Amino Acid Sequence↗

PubMed1997

Critical stages of tumor growth regulation in transgenic mice harboring a hepatocellular carcinoma revealed by distinct patterns of tumor necrosis factor-alpha and transforming growth factor-beta mRNA production.

There is now good evidence that cytokines contribute to the regulation of tumor growth. The cytokine-driven modulation of tumor growth was investigated during the progression of a hepatocellular carcinoma (HCC) in SV40 large T tumor antigen transgenic mice. In vivo, an increased rate of liver growth correlated with increased transforming growth factor (TGF)-beta 1 mRNA expression, while the greatest amounts of tumor necrosis factor (TNF)-alpha mRNA were detected earlier during tumor development. Conversely, no particular alteration of IL-1 alpha, IL-1 beta, IL-6, IL-2, IL-4 and IFN-gamma mRNA production could be reported. In vitro, hepatocyte-like tumor cell lines established at two stages, either before or after HCC differentiation, were characterized. The early-stage-derived cell line produced TNF-alpha mRNA, but had barely detectable expression of TGF-beta 1 mRNA, while later-stage-derived cell lines showed the reciprocal pattern. All cell lines displayed a lack of sensitivity to TNF-alpha, although some degree of sensitivity to TNF-alpha could be observed in the presence of actinomycin-D or after treatment with IFN-gamma. The early-stage-derived cell line was sensitive to the growth inhibitory effects of TGF-beta 1, but late-stage-derived tumor cell lines displayed a loss of sensitivity to TGF-beta 1 which correlated with the increased expression of TGF-beta 1 mRNA. Altogether, this suggests that tumor cells contribute to the discrete TNF-alpha and TGF-beta 1 expression patterns during HCC progression. This model of HCC could be of valuable interest to assess the impact of various immunotherapeutic strategies on modulation of tumor growth.

Animals↗

PubMed1996

A wild-type p53 cytotoxic T cell epitope is presented by mouse hepatocarcinoma cells.

The possibility to identify epitopes presented by tumor cells to cytotoxic T lymphocytes (CTL) has given rise to new fields in tumor immunology. The tumor suppressor gene product p53 is a good candidate antigen because it is involved in the tumorigenesis of many cancers. It accumulates in an inactivated form due to mutation or formation of heterodimers with an oncogene product. Epitopes from the mutant or wild-type p53 proteins are thought to be presented by tumor cells and to induce a tumor-specific CTL response. To identify such epitopes, mouse wild-type p53 peptides encompassing the H-2 Db anchoring motif were tested for their association with the Db molecule. Positive peptides were assayed for their ability to induce CTL in C57BL/6 mice. CTL specific for one wild-type p53 peptide, p232-240, were isolated and found to lyse hepatocarcinoma cell lines established from mice transgenic for simian virus 40 large T antigen which overexpress p53. These results show that the p232-240 epitope from wild-type p53 is naturally processed and presented in H-2b tumor cells.

Animals↗

PubMed1994

Epitope analysis of T- and B-cell response against the human beta 1-adrenoceptor.

Several reports have recently raised the possible significance of the presence of autoantibodies against the beta 1-adrenoceptor in patients with idiopathic dilated cardiomyopathy. An investigation was thus initiated to study the immune response against this receptor at the T-cell and the B-cell level. Using membranes of E coli transfected with the human beta 1-adrenoceptor gene as immunogen, T-helper cells of the immunized mice were stimulated with synthetic peptides derived from the receptor and predicted to be immunogenic to assess the T-cell immunodominant regions of the receptor. Three peptides derived from the second transmembrane region, from the second extracellular loop and from the C-terminal domain were shown to be stimulatory. Synthetic peptides, derived from two domains of the receptor which could be potential targets for autoantibodies, yielded an antibody response after immunization with the free peptides. The peptide derived from the N-terminal region yielded antibodies which recognized the receptor in immunoblot and by immunoprecipitation but they had no functional effect on the receptor. The peptide derived from the second extracellular loop yielded antibodies which recognized the receptor in immunoblot and by immunoprecipitation of the free receptor and which had a pharmacological effect on the receptor. The second extracellular loop thus contains T- and B-cell epitopes which could be involved in the autoimmune process.

Animals↗

PubMed1990

Induction of mouse syngeneic MLR by in vivo xenogeneic immunization with HLA-DR antigens.

To study in mice the effects of in vivo xenogenic immunization with human major histocompatibility complex (MHC) class II antigens, the animals were injected with HLA-DR antigens and their proliferative responses tested in vitro. The results showed that small amounts of HLA-DR proteins, acting as nominal antigens, were not only able to prime mice for a secondary in vitro xenogenic mixed lymphocyte reaction but also induced a syngeneic mixed lymphocyte reaction. In contrast, allogeneic or syngeneic immunization of mice with soluble MHC class II molecules failed to stimulate an autoreactive response. The syngeneic mixed lymphocyte reaction was primarily directed against syngeneic MHC class II molecules since the murine T lymphocytes reacted against MHC class II-positive dendritic spleen cells and MHC class II-transfected mouse fibroblasts. A self-reactive T-cell line induced under these experimental conditions did not react in xenogeneic and allogeneic mixed lymphocyte reactions. However, these T lymphocytes proliferated when human peripheral blood lymphocytes of various haplotypes were presented in the context of syngeneic mouse antigen presenting cells.

Animals↗

PubMed1990

The invariant chain forms complexes with class II major histocompatibility complex molecules and antigenic peptides "in vivo".

The binding of a chicken ovalbumin peptide (residues 323-339), Ova-(323-339), to I-Ad molecules was investigated in vitro and in vivo. By using antigenic peptides labeled either with a hapten or with fluorescein, complexes formed in vitro between I-Ad and antigenic peptides were detected by Western blot analysis with an antibody recognizing the hapten 7-nitrobenzo-2-oxa-1,3-diazole and by scanning gels for fluorescence emitted by fluoresceinated peptide. Both techniques reveal that Ova-(323-339) binds not only to I-Ad alpha/beta heterodimers and separated alpha and beta chains but also to complexes of higher molecular mass. Additional analysis shows that one of these additional complexes contains I-Ad heterodimers, antigenic peptides, and also invariant chain. To explore the physiological role of these complexes, cells were incubated with haptenated peptide and the I-Ad-peptide complexes formed in vivo were purified by affinity chromatography using hapten-specific antibody. The complexes formed migrate with a significantly higher apparent molecular mass than the alpha/beta heterodimers. A band at 180 kDa contained the alpha/beta heterodimer, the antigenic peptide, and the invariant chain. These results show that in vivo high molecular mass complexes formed by the I-Ad heterodimer and the invariant chain bind antigenic peptides.

Animals↗

PubMed1987

Xenogeneic recognition of soluble and cell surface HLA class II antigens by proliferative murine T cells.

In order to characterize the murine anti-human xenogeneic mixed lymphocyte reactions (MLR), we studied T cell proliferative responses against various human lymphoid cells by immunization of mice either with cellular or purified HLA-DR antigens. Data presented here indicated that small amounts of soluble HLA-DR antigen were able to prime mice, and that the xenogeneic MLR depends on the expression of HLA class II antigens on the stimulating cells. Experiments using a mutant cell line clearly showed that HLA-DP molecules were also sufficient in eliciting a primary or a secondary xenogeneic MLR while no secondary proliferative response was obtained with cells expressing only HLA class I molecules. Using a large panel of human cells with various haplotypes, our results also showed that (a) nonpolymorphic determinants of HLA class II antigens trigger dominantly the murine T cells and (b) the xenogeneic response required I-E and L3T4 accessory molecules and was not inhibited with anti I-A and monomorphic anti-HLA class II antigen monoclonal antibodies. Altogether these results suggest that HLA class II antigens act as nominal antigens in triggering a murine anti-human proliferative response.

Animals↗

PubMed1987

Monoclonal B-cell response to diphtheria toxoid: evidence for cross-reactive epitopes.

Our previous studies on the human specific B- and T-cell responses against diphtheria toxoid (DT) had shown that the B- and T-cell antigenic determinants were mostly assembled topographic sites with large intra-molecular cross-reactivities. In order to characterize further the B-cell responses against DT, and to investigate these cross-reactivities, we have produced 54 murine monoclonal antibodies (moAbs) against the native DT. Determination of their antigenic specificity showed that 25 moAbs recognized conformational determinants on the native DT, 20 moAbs reacted against the A fragment (DTA) of the toxin, and nine moAbs reacted with at least three distinct highly purified CNBr peptides of the B fragment (DTB); some of them simultaneously recognized two or three purified CNBr peptides of DTB. As shown by cross-inhibition studies, the epitopes cross-reacting with those moAbs were distinct. Previously described sequence data indicated that these epitopes were not induced by repetitive amino-acid sequences. Finally, a cross-reactive idiotype was shared by moAbs specific for the CB1 and the CB3 peptides of DTB. Altogether, these data indicate that anti-DT moAbs are mostly directed against conformational determinants, and may cross-react with several DTB CNBr peptides.

Animals↗

PubMedDate not supplied

[Herpetiform ulceration: 5 cases].

BACKGROUND: Mouth ulcers are frequently observed, mostly caused by trauma and aphthae. We report five cases of herpetiform ulceration, a rare clinical form of aphthae often mistaken for herpetic stomatitis because of the similar clinical presentation. CASE REPORTS: All patients were men with late age at onset (44.8 years). All had numerous tiny very painful ulcers covering all parts of the oral cavity. Consequences were sometimes severe (weight loss and general weakness in two patients, requiring hospitalization in one). Diverse clinical courses were observed (from no recurrence to monthly recurrence). Systemic steroids resulted in dramatic improvement in two patients, colchicine prevented recurrences in three of them. DISCUSSION: These observations illustrate well this rare disease: herpetiform ulceration. We found oral corticosteroids provide effective cure and observed the preventive action of colchicine. Both findings should be confirmed in larger series.

Adult↗

PubMedDate not supplied

[A reddened eye].

Explore the source record for details and available documents.

Amoxicillin-Potassium Clavulanate Combination↗

PubMedDate not supplied

[Painful bruising syndrome mimicking cellulitis of the leg].

BACKGROUND: Autoerythrocyte sensitization syndrome (painful bruising syndrome) is marked by spontaneous and painful ecchymotic bruising, without any biological abnormality, occurring in women with pathological mental profile. Sometimes, when the inflammation is severe, an infectious cellulitis or muscular compression may be suspected. CASE REPORT: A 21-year-old woman was referred for the rapid occurrence of a diffuse and painful inflammation of the right leg, with fever. The leg was red, warm, with diffuse bruising. The foot was fixed in varus equin. The biological parameters were normal. Magnetic resonance imaging showed normal muscles but modifications in the subcutaneous fat, similar to an acute cellulitis. A cutaneous biopsy showed a moderate oedema of the dermis and erythrocyte extravasation. Antibiotics were inefficient on the pain and the aspect of the lesions. Because of the efficacy of saline serum injections on the symptoms and a pathological psychological profile, an autoerythrocyte sensitization syndrome was suspected. The skin test was negative. Psychiatric evaluation revealed a severe personality disorder associated with depression. The ecchymotic lesions disappeared with adapted psychiatric treatment. DISCUSSION: Painful bruising syndrome occurs most often in young women with various psychiatric problems. The lesions are characterized by recurrent, painful, swollen and bleeding bruises in any part of the body. Fever, abdominal pain and external bleeding are possible. Haematological and immunological findings are usually normal. The histology of early lesions reveals oedema of the dermis and modest perivascular infiltrate, whereas extravasated erythrocytes appear later. The magnetic resonance imaging aspect of the lesions has never been described. Abnormalities of the subcutaneous fat are similar to those of acute cellulitis, expressing the inflammation process secondary to the ecchymoses. The syndrome results from complex somatic and psychological mechanisms. Many drugs were tried for the treatment of the disease, without any significant improvement.

Adult↗

PubMedDate not supplied

Homogeneous immunoassays using rare earth cryptates and time resolved fluorescence: principles and specific advantages for tumor markers.

We have developed a new type of long lived fluorescent tracer, the rare earth cryptates formed by the inclusion of a Eu3+ ion into the intra molecular cavity of a macrobicyclic ligand containing bipyridine units. This tracer is used in a new homogeneous assay format based on spectral and temporal selectivity as well as on an amplification of the cryptate fluorescence. As a consequence of these features, the measurement of the specific signal is totally shielded from media interaction and corrected in real time for sample to sample optical variation. We show the example of a PSA assay where an analytical sensitivity of 0.03 ng/ml is obtained and an AFP assay where measurements in the first minutes of the incubation allow a rapid estimation of the AFP concentration and therefore an immediate dilution of the samples if required. These results illustrate the performance of this new homogeneous method and point out the specific advantages it allows in terms of sensitivity, precision and flexibility. It is therefore particularly well adapted for the assay of analytes like tumor markers where both sensitivity and wide dynamic range are needed.

Biomarkers, Tumor↗

PubMedDate not supplied

Does preventive vaccination with engineered tumor cells work in cancer-prone transgenic mice?

The use of genetically modified tumor cells as vaccines has been successful in numerous animal models of grafted syngenic tumors and has provided the groundwork for many clinical trials of gene therapy in cancer patients. To investigate the real efficacy of ex vivo gene therapy-based vaccines, we used transgenic mice that express the SV40 large T and small t antigens under the control of hepatic antithrombin III (ASV-B)-regulatory sequences. These mice systematically develop hepatocarcinoma. Hepatoma cells, derived from ASV-B transgenic mice, were gene-transduced to express either interleukin-2, interleukin-4, the granulocyte-macrophage colony-stimulating factor, or the T-cell costimulatory molecule B7.1. First, we demonstrated the vaccine potential of engineered hepatoma cells by immunizing nontransgenic mice with these cells, which prevented the growth of subsequent grafted nontransduced hepatoma cells. However, vaccination of pretumoral transgenic animals with various combinations of engineered hepatoma cells failed to inhibit hepatoma onset and progression. Rather, tumor development in ASV-B mice appears to be dependent on the immune system, since neonatal induction of immunotolerance to tumor in ASV-B mice cells was associated with a moderate, but significant, acceleration of tumor development. These results seriously call into question the efficacy of this strategy of active vaccinotherapy against natural tumors.

Animals↗