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J Tassignon

Publications and source records attributed to J Tassignon.

8 recordsLinked to original sources
PubMed2001

Azodicarbonamide as a new T cell immunosuppressant: synergy with cyclosporin A.

We recently demonstrated that azodicarbonamide is an immunosuppressive compound that inhibits calcium mobilization in T lymphocytes. In this study, we show that azodicarbonamide prevents the progression of human CD4+ T lymphocytes into the G1 phase of the cell cycle, inhibits their blastogenesis, down-regulates their membrane expression of CD25 and CD69, and decreases their transcription of cytokine genes. Addition of the calcium ionophore A23187 completely restores T cell proliferation in the presence of azodicarbonamide. Furthermore, azodicarbonamide synergizes with cyclosporin A to inhibit CD4+ T cell proliferation. In conclusion, the immunosuppressive action of azodicarbonamide is mainly related to its effect on the calcium mobilization machinery and is synergistic with that of calcineurin inhibitors.

Adult↗
PubMed1999

Azodicarbonamide inhibits T-cell responses in vitro and in vivo.

Azodicarbonamide was recently identified as a new anti-HIV agent that targets the zinc finger domains of the HIV-1 NCp7 nucleocapsid protein. Here, we demonstrate that azodicarbonamide inhibits in a dose-dependent manner the responses of purified human CD4+ T lymphocytes stimulated either by monoclonal antibodies against CD3 and CD28 or by allogeneic dendritic cells. These suppressive effects involve a direct action on the calcium mobilization machinery, as azodicarbonamide strongly inhibited the calcium influx induced either by antibodies against CD3 and CD28 or the chemokine RANTES, as well as by thapsigargin, an activator of depletion-activated calcium channels. In vivo, administration of azodicarbonamide into mice blunted their response to polyclonal T-cell activation induced by the injection of monoclonal antibody against CD3 and resulted in delayed rejection of skin allografts. In addition to its anti-HIV properties, azodicarbonamide is a new immunosuppressive agent that might have therapeutic applications in T cell-mediated inflammatory disorders.

Animals↗
PubMed1997

Natural antiestrogen receptor autoantibodies in man with estrogenic activity in mammary carcinoma cell culture: study of their mechanism of action; evidence for involvement of estrogen-like epitopes.

We previously reported that human natural autoantibodies enriched in antiestrogen receptor Ig (IgGs) display estrogenic activity in MCF-7 mammary carcinoma cells. In this study, we investigated IgGs' mechanism of action. We showed that: 1) IgGs Fab fragments (which contain only one antigen binding site) induced an estrogenic response in MCF-7 cells, producing estrogen receptor (ER) down-regulation and an increase in progesterone receptor concentration; 2) IgGs specifically inhibited MCF-7 cell surface labeling with fluorescent estradiol (E2)-BSA conjugates; 3) this inhibition of E2-BSA binding to membrane estrogen binding sites was largely caused by natural anti-E2-BSA antibodies (Ab) selectively associated with the natural anti-ER Ab within IgGs; 4) furthermore, these natural anti-E2-BSA Ab accounted for most of IgGs estrogenic activity in cell culture; 5) however, when incubated with cytosolic ER, they did not behave like estrogens, but they decreased ER hormone binding capacity; and 6) although IgGs stimulated cAMP production, their anti-E2-BSA Ab subpopulation did not. In conclusion, the estrogenic activity of IgGs does not involve Ab mimicking E2 molecular configuration or ligand-independent cAMP mediated pathways, membrane Fc receptors, and membrane receptor cross-linking mechanisms. On the contrary, IgGs seem to function by neutralizing estrogen-like epitopes, associated with ER-related peptides, which might inhibit ER activation.

Animals↗
PubMed1993

Molecular characterization of monoclonal CRIA-positive anti-arsonate antibodies derived from idiotype-negative mice bearing a light chain polymorphism.

We have elicited anti-arsonate antibodies bearing the major cross-reactive idiotype (CRIA) in a double congenic idiotype-negative strain (C.C58.AL-20) bearing a light chain polymorphism that has previously been shown serologically not to complement idiotype-positive heavy chains. Using the idiotype cascade (Ab1-->Ab2-->Ab3-->-->Ab1'), CRIA-positive antibodies were raised and monoclonal antibodies were isolated and characterized serologically and by nucleotide sequence analysis. Two types of idiotype-positive anti-arsonate antibodies were generated in the C.C58.AL-20 strain. One group of hybridomas used the canonical VH1.8 heavy chain gene segment with V kappa 10 variant light chains. A second group used a VHGAM3.8 heavy chain with V kappa 10 variant light chains. This latter heavy-light pairing has been observed in CRIA-like responses previously in BALB/c mice after idiotypic manipulation (or rarely after antigen alone). These studies demonstrate the plasticity of the immune response when manipulated with idiotype reagents as well as its structural variability. Additionally, they provide important insights into the potentials of idiotype vaccines.

Amino Acid Sequence↗
PubMed1987

The influence of V kappa gene polymorphism on the induction of silent idiotypes in the arsonate system.

It has been previously shown that it is possible to modify the expressed repertoire of a given individual using idiotypic manipulation. For example, A/J mice respond to arsonate challenge by synthesizing a dominant idiotype, CRIA, whereas BALB/c mice do not. However, after treatment with rabbit polyclonal anti-CRIA antibodies (Ab2 or anti-idiotypic antibodies) and arsonate, BALB/c mice are able to synthesize a CRIA-like idiotype. To determine whether this modification of repertoire is dependent on the immunoglobulin loci (Ig-h, kappa), we have analyzed the anti-arsonate response after anti-idiotypic treatment of three strains of mice (C58, C.C58, AKR), chosen because they are among a small group of strains which express Kappa V regions not seen in other strains. There are also L chains lacking in these strains which are expressed in other mice. The C58 and C.C58 strains share the same Ig-h locus (Ig-ha) with BALB/c mice but C.C58 are congenic mice, that express the kappa loci on a BALB/c genetic background. AKR mice express the Ig-hd haplotype. AKR, C58 and C.C58 do not produce CRIA positive antibodies in response to arsonate; a defect which has been previously mapped to the kappa locus. These three strains of mice (C58, C.C58 and AKR) were treated with rabbit anti-CRIA and boosted with Ars-KLH. The results show that after such treatment, the C.C58 mice were able to express CRIA-like antibodies which are serologically identical to those of BALB/c.

Animals↗
PubMed1986

Idiotypic games within the immune network.

In this paper, we have considered the problem of selection of available repertoires. With Ab2 as immunogens, we have used the idiotypic cascade to explore potential repertoires. Our results suggest that potential idiotypic repertoires are more or less the same within a species or between different species. A given idiotype "à la Oudin" can become a recurrent one within the same outbred species or within different species. Similarly, an intrastrain crossreactive idiotype can be induced in other strains, even though there is a genetic disparity between these strains. The structural basis of this phenomenon has been explored. We next examined results showing the loss and gain of recurrent idiotypes without any intentional idiotypic manipulation. A recurrent idiotype can be lost in a syngeneic transfer and a private one can become recurrent by changing the genetic background. The change of available idiotypic repertoires at the B cell level has profound influences on the idiotypic repertoires of suppressor T cells. All these results imply that idiotypic games are played by the immune system itself, a strong suggestion that the immune system is a functional idiotypic network.

Animals↗