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Y Jacques

Publications and source records attributed to Y Jacques.

At least 55 records · Page 3Linked to original sources
PubMed1995

Characterization of a monoclonal antibody directed against the NH2 terminal area of interleukin-2 (IL-2) and inhibiting specifically the binding of IL-2 to IL-2 receptor beta chain (IL-2R beta).

An anti-human IL-2 mAb (19B11/beta) was found to selectively block the binding of IL-2 to TS1 beta cells expressing the interleukin-2 receptor beta (IL-2R beta) without affecting binding to TS1 alpha cells expressing the IL-2R alpha receptor. It also specifically inhibits the IL-2 driven cell proliferation in TS1 beta cells. These observations have lead to the hypothesis that its epitope is related to an IL-2 area involved in binding with IL-2R beta chain. This epitope was identified using various peptides covering the N-terminal half (including alpha helix A) of the 133 amino acids of IL-2. MAb 19B11/beta does not recognize peptides 30-54 and 44-54 but recognizes peptides 1-22 and 1-30 with a good affinity. Furthermore, threonine in position no. 3 was found to be critical for the binding of mAb 19B11/beta. A relationship between the epitope of mAb 19B11/beta and the glycosylation of the IL-2 molecule was observed. This further demonstrates that the NH2 terminal area of IL-2 is critical for IL-2/IL-2R beta interactions. Two other mAbs were studied during the course of this work. They served as control for the study of mAb 19B11/beta and provide some additional insight concerning the question of IL-2/IL-2R structure-function. MAb 16F11/alpha selectively blocks the IL-2 binding to TS1 alpha cells. The epitope of mAb 16F11 is conformational and it was not possible to study the corresponding IL-2/IL-2R alpha region of interaction. Epitope of mAb 3H9 is localized between residues 30 and 54 and does not affect the binding of IL-2 to IL-2R alpha.

Amino Acid Sequence↗
PubMed1995

Immunological characterization of antigenic domains on human IL-2 receptor beta subunit: epitope-function relationships.

Five mAb directed at the IL-2R beta chain were analyzed for their binding and functional properties. They define three epitopes on a recombinant soluble beta chain or on the beta chain expressed at the surface of YT-2C2 cells. Epitope 1 (A41 and 6E8 mAb) is part of the IL-2 binding domain, whereas epitope 2 (CF1 and 6E10 mAb) is not involved in IL-2 binding. Epitope 3 (6B5 mAb) also partly overlaps the IL-2 binding domain but does not overlap epitopes 1 and 2. None of the mAb can by themselves inhibit IL-2 induced proliferation of a human activated T cell clone. Only epitope 1 mAb can synergize with an anti-alpha chain mAb to inhibit this proliferation. Using epitope 1 and 2 mAb as well as a purified, recombinant form of the IL-2R beta chain extracellular domain, an ELISA-based immunoassay was set up which allows the quantitative determination of soluble and detergent solubilized IL-2R beta chains. Epitopes 1 and 2 are in non-competitive interaction: the binding of a mAb to one epitope decreases the affinity of a mAb for the second epitope. Epitope 2 mAb have binding stoichiometries (approximately 16,000 sites/cell) which are approximately 80% higher than that of epitope 1 mAb and IL-2 itself (approximately 9000 sites/cell). Upon binding of epitope 2 mAb, the stoichiometries of epitope 1 mAb and IL-2 are increased to reach the stoichiometry of epitope 2 mAb.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Monoclonal↗
PubMed1994

Rat interleukin-2 immunoglobulin M fusion proteins are cytotoxic in vitro for cells expressing the IL-2 receptor and can abolish cell-mediated immunity in vivo.

A hybrid cDNA coding for a fusion protein between rat interleukin 2 (IL-2) and a truncated heavy chain from rat immunoglobulin M (IgM) was constructed. The rat IL-2 and rat IgM CH2-3-4 hybrid gene was subcloned into a vector (PKCR6) for expression of the fusion molecule in Chinese hamster ovary (CHO) cells. Cells transfected with the hybrid cDNA secrete multimeric forms of the fusion protein (IL-2-Mu). Size analysis of the construct revealed that the majority (95%) of the secreted proteins have a high mw (> 500 kDa). The IL-2-Mu construct bind specifically to cells bearing the IL-2 receptors (IL-2R) with a binding affinity around 5 nM. The specific binding to IL-2R leads to T cell proliferation or, if rabbit complement is added, to T cell lysis. Multimeric forms (> 500 kDa) of the fusion protein mediate complement-dependent lysis but trigger only weak proliferation when compared with the low-mw forms (< 500 kDa). In contrast, the latter only efficiently mediate T cell proliferation without inducing complement-dependent lysis. After intravenous administration of CHO supernatant containing IL-2-Mu, or purified IL-2-Mu proteins into rats, the fusion proteins disappeared from the circulation with a t1/2 of 1 hr. The circulating IL-2-Mu constructs in the rat serum retained their capacity to induce complement-dependent lysis of IL-2R-bearing T cells in vitro. Furthermore, the IL-2-Mu construct was able to suppress the delayed-type hypersensitivity (DTH) reaction (an IL-2R, T helper cell-dependent event) in mice. A weak immune response (antirat IL-2-Mu antibodies) was observed when rats received multiple daily injections of the construct.

Animals↗
PubMed1994

Heterodimerization of the IL-2 receptor beta- and gamma-chain cytoplasmic domains is required for signalling.

The interaction of interleukin-2 (IL-2) and IL-2 receptors critically regulates the T-cell immune response following antigen activation. IL-2 can signal through high or intermediate affinity receptors which contain IL-2R alpha (refs 3, 4) +beta (refs 5-8) +gamma (ref. 9) or beta+gamma chains, respectively. IL-2R gamma is a common gamma chain, gamma c, also shared by the IL-7 (ref. 10) and IL-4 (refs 11, 12) receptors, which when mutated results in X-linked severe combined immunodeficiency. Using chimaeric receptor constructs together with monoclonal or bispecific antibodies we demonstrate here that IL-2 signalling requires ligand-induced extracellular-domain-mediated heterodimerization of the beta- and gamma c-chain cytoplasmic domains. Anti-IL-2R alpha monoclonal antibodies trigger proliferation of cells transfected with chimaeric constructs in which the extracellular domains of IL-2R beta and gamma c are replaced by that of IL-2R alpha. Other experiments using chimaeric constructs indicated that IL-2 binds monomerically and monovalently to IL-2R alpha and that the beta-transmembrane domain is not required for receptor chain interactions. Finally, we provide a method for mapping residues in the gamma c cytoplasmic domain even in cells that constitutively express gamma c.

Animals↗
PubMed1994

Modulation of associated ovarian carcinoma antigens by 5 cytokines used as single agents or in combination.

Optimization of intraperitoneal radioimmunotherapy of ovarian cancer depends on increasing the antigenic expression of tumor cells. For this purpose, we studied the effect of 5 cytokines (IFN-alpha, IFN-beta, IFN-gamma, TNF-alpha and TGF-beta), used as single agents or in combination, on 4 ovarian cancer cell lines which present different antigenic profiles with the monoclonal antibodies (MAbs) tested (OC125, OVTL-3, MOv 18 and MOv 19). Analyses were performed by flow cytometry and the Scatchard technique in order to study antigenic modulation. The effect on proliferation was determined by cell counting. Expression of O3 antigen, recognized by the OVTL3 MAb, was increased up to 2.5 times after IFNs and TNF-alpha (used as single agent) on the 2 lines presenting low basal expression (SHIN-3 and IGROVI). The expression of CA125 antigen and the antigens recognized by MOv 18 and MOv 19 MAbs was not increased by any of the cytokines tested. The combination IFN-gamma+TNF-alpha was synergistic on cytotoxicity and enhanced O3 expression, providing 10 times as many sites per cell on the SHIN-3 line. For 3 other associations (IFN-alpha+IFN-gamma, IFN-beta+IFN-gamma and IFN-alpha+TNF-alpha), there was an additive effect on O3 expression and on cell cytotoxicity.

Antigens, Neoplasm↗
PubMed1994

Effect of plasma protein adsorption on protein excretion in kidney-transplant recipients with recurrent nephrotic syndrome.

BACKGROUND: Among patients with the idiopathic nephrotic syndrome who have focal and segmental glomerulosclerosis and undergo renal transplantation, 15 to 55 percent have recurrent nephrotic syndrome. The recurrence may be caused by a plasma factor or factors that increase glomerular permeability, because plasma exchange transiently decreases or abolishes proteinuria in some patients. We studied the effect on proteinuria of the removal of protein (mostly immunoglobulins) by adsorption onto protein A from the plasma of patients with recurrent nephrotic syndrome. METHODS: Eight patients were treated with one to three cycles of two to seven 1-day sessions of protein adsorption, and the patients' urinary protein excretion was measured repeatedly. Their immunosuppressive regimens were not changed during the treatment. The adsorbed proteins were eluted from the protein A and injected into rats, and the urinary albumin excretion of the rats was measured. RESULTS: The protein-adsorption treatment consistently decreased urinary protein excretion by an average of 82 percent at the end of a cycle (P < 0.001). In one patient proteinuria disappeared, and in another urinary protein excretion remained below 2.5 g per day with repeated cycles of protein adsorption. In all but one patient the effect of adsorption was limited in time, with a return to the preadsorption level of protein excretion within a maximum of two months. The administration to rats of material eluted from the protein A increased urinary albumin excretion 2.9- to 4.6-fold (P < 0.001 and P = 0.005, respectively). Although protein A primarily binds immunoglobulins, the active fraction of the eluted proteins had a molecular weight below 100,000, indicating that immunoglobulin was not directly involved. CONCLUSIONS: Adsorption of plasma protein decreases urinary protein excretion in patients with recurrence of the nephrotic syndrome after renal transplantation. Studies of the adsorbed proteins should provide information about the mechanism of this disease.

Adolescent↗
PubMed1994

Prevention of acute rejection episodes with an anti-interleukin 2 receptor monoclonal antibody. I. Results after combined pancreas and kidney transplantation.

A prospective, randomized trial was conducted to evaluate the short-term and long-term effects of induction immunosuppression with the rat IgG 2a monoclonal antibody 33B3.1, directed against the human alpha chain of the interleukin 2-receptor, following primary, cadaveric, combined pancreas and kidney transplantation. Forty patients were randomly assigned to receive 10 mg/day of 33B3.1 (n = 20) or 1.5 mg/kg/day of rabbit antithymocyte globulin (n = 20) for the first 10 postoperative days. Azathioprine, low-dose corticosteroids, and cyclosporine were given in association with either 33B3.1 or ATG. All 40 patients received the entire 10-day bioreagent course and no episode of rejection was observed during this period. Although the incidence of rejection did not significantly differ within the first, second, and third postoperative months (ten 33B3.1 and 6 ATG patients experienced, respectively, 10 and 6 rejection episodes within the first 3 months), the total number of 33B3.1 patients experiencing rejection throughout the follow-up was significantly higher than that of ATG (13 versus 6; P < 0.02). Immunological graft failure accounted for 2 pancreas and 2 kidney losses in the 33B3.1 group versus 1 in the ATG one (P = ns). The total number of infectious episodes was similar in both groups (21 versus 23). Two malignancies were observed in the ATG group (1 responsible for patient's death). One 33B3.1 patient died because of infectious pneumonia and 3 ATG patients died because of 2 cardiovascular diseases and 1 cancer. All patients had functioning grafts at the time of death. The 3-month and 36-month patient, pancreas, and kidney actuarial survival rates were, respectively, 100, 65, and 100%, and 95, 50, and 82% in the 33B3.1 group and 95, 80, and 90%, and 80, 70, and 80% in the ATG one (P = ns). These data suggest that, although a significantly higher rejection episode incidence was observed in patients treated with 33B3.1 monoclonal antibody as compared with ATG, similar long-term results can be obtained following primary cadaveric combined pancreas/kidney transplantation.

Acute Disease↗
PubMed1994

Prevention of acute rejection episodes with an anti-interleukin 2 receptor monoclonal antibody. II. Results after a second kidney transplantation.

The focus of progress in transplantation immunosuppression is to achieve more specific immunosuppression with monoclonal antibodies. We have already shown that the efficacy of 33B3.1, a rat monoclonal Ig2A directed against the human IL-2 receptor, was similar to that of rabbit antithymocyte globulin in the prevention of acute rejection in first kidney transplants. A similar comparative analysis has been made in 40-sec renal transplants. ATG (1 mg/kg/day) or 33B3.1 (10 mg/day) was administered during the first 10 days postgrafting in association with corticosteroids and azathioprine. Cyclosporine was introduced on day 9 and azathioprine/CsA constituted the patient's maintenance treatment after day 45. Rejection treatment consisted of equine antilymphocyte globulin in both cases and of steroid boluses when patients were under Cyclosporine. One patient in each group died. Graft survival was 90%, 85%, and 79% in the ATG group (n = 20) and 100%, 89%, and 89% in the 33B3.1 group (n = 20) at 3, 12, and 24 months, respectively. Of the ATG group patients, 45% and 40% in the 33B3.1 group had at least one rejection episode, half the episodes in the MoAb cohort occurring under 33B3.1, vs. none in the ATG group. Transplant function was similar in both groups. Viral infections appeared to be more frequent with ATG (60%) than with 33B3.1 (12%), with CMV accounting for half of these in the ATG group, and none in the MoAb group. Tolerance of both agents was good. Of the 33B3.1 recipients, 70% developed anti-33B3.1 antibodies. From these data, we conclude that this anti-IL-2 receptor MoAb seems less effective than rabbit ATG as induction treatment in second kidney transplant patients.

Acute Disease↗
PubMed1993

Secretion of disulfide-linked human T-cell receptor gamma delta heterodimers.

The availability of soluble forms of T-cell antigen receptors (sTCR) should be of great use in the detailed characterization of their interactions with ligands, for the generation of anti-TCR monoclonal antibodies (mAb), and for the eventual determination of their three-dimensional structures by x-ray crystallography. Here, we show that efficient secretion of nonchimeric disulfide-linked human gamma delta TCR could be achieved by simply introducing translational termination codons upstream from the sequences encoding TCR chain transmembrane regions. This recombinant protein appeared to be correctly folded, as judged by its reactivity with a panel of anti-gamma and anti-delta mAbs, and proved to be a powerful immunogen, allowing generation of mAb that are able to recognize both soluble- and membrane-bound gamma delta TCR. While variable and constant domains of gamma delta sTCR seem to be folded into compact conformations, the extreme sensitivity of its interchain disulfide bridge to digestion with papain suggests that sTCR C-terminal portions are in a more extended configuration than the corresponding region in immunoglobulins. Finally, the gamma delta heterodimer remains stable even after removal of the interchain disulfide link, suggesting the existence of strong noncovalent forces holding the two chains together.

Amino Acid Sequence↗
PubMed1993

Construction of a bispecific antibody reacting with the alpha- and beta-chains of the human IL-2 receptor. High affinity cross-linking and high anti-proliferative efficiency.

A bispecific antibody recognizing both the alpha- and beta-chains of the IL-2R was generated by sulfhydryl-directed chemical reassociation of monovalent Fab' fragments prepared from the anti-alpha mAb 33B3.1 (rat IgG2a) and from the anti-beta mAb A41 (mouse IgG1). Whereas the 33B3.1/A41 bispecific mAb (bi-mAb) binds to isolated alpha- and beta-chains with low affinity (Kd = 4 nM), its binding to cells co-expressing the two chains shows both low and high affinity components. The high affinity-binding sites (Kd = 100 pM) most probably correspond to the cross-linking by the bi-mAb of alpha- and beta-chains, whereas the low affinity component corresponds to the excess of alpha-chains. High affinity binding of bi-mAb on activated T cells is observed at 37 degrees C and not at 4 degrees C, suggesting that i) the two chains are dissociated at 4 degrees C in the absence of ligand and ii) the mechanism of bi-mAb catalyzed cross-linking of these two chains is temperature dependent. In contrast to parental 33B3.1 and A41 IgG, which recognize single positive (alpha + and beta +, respectively) and double positive alpha +/beta + cells with similar affinities, the 33B3.1/A41 bi-mAb is specific for activated alpha +/beta + cells with respect to its high affinity binding. In contrast to A41, which does not affect IL-2-induced proliferation of 4AS cells or anti-CD3-activated PBL, and to 33B3.1, which do inhibit proliferation but only partially and at high doses, the bi-mAb showed full blocking efficiencies at low concentrations (IC50 of 300 to 400pM) corresponding to the formation of high affinity alpha/bi-mAb/beta complexes. These half-maximal effects were observed at 10-fold lower concentrations than when using a combination of equimolar concentrations of parental 33B3.1 and A41 IgG. Because of their specificity and high blocking efficiencies, anti-alpha/anti-beta bi-mAb may constitute a better alternative for IL-2R-directed immunosuppression.

Humans↗
PubMed1993

Generation of monoclonal antibodies against HILDA/LIF and their use in the quantitative assay of the cytokine.

An adoptive transfer immunization/fusion protocol in mice has been successfully used to raise a series of monoclonal antibodies directed against the Human Interleukin for DA-1a (HILDA)/Leukemia Inhibitory Factor (LIF) cytokine. These antibodies which were raised using recombinant HILDA/LIF purified from conditioned medium of transfected Chinese Hamster Ovary (CHO) cells also react with natural HILDA/LIF from the HSB2 T lymphoma cell line and unglycosylated HILDA/LIF produced in E. coli. They define four separate epitopes, one of which is involved in receptor binding and induction of biological activity. A sensitive sandwich immunoradiometric assay which is linear up to 5 ng/ml HILDA/LIF and can detect as low as 25 pg/ml of the cytokine has been developed.

Animals↗
PubMed1993

Kistrin, an integrin antagonist, blocks endocytosis of fibrinogen into guinea pig megakaryocyte and platelet alpha-granules.

Recent data indicate that megakaryocyte/platelet alpha-granule fibrinogen is endocytosed from plasma. Because fibrinogen is the major platelet protein present in high concentrations in alpha-granules, fibrinogen uptake into alpha-granules may occur via specific receptors. In that cells of the megakaryocyte/platelet lineage contain two integrins--alpha IIb beta 3 (GP IIb-IIIa) and the vitronectin receptor (alpha v beta 3)--that can bind fibrinogen, one or both of these receptors may mediate the endocytic uptake of fibrinogen. To test this hypothesis, we examined the effect of Kistrin, an RGD-containing protein purified from the venom of Agkistrodon rhodostoma that inhibits fibrinogen binding to human platelet receptors, on endocytosis of fibrinogen by megakaryocytes and platelets. Continuous intravenous infusion of kistrin into guinea pigs (200 micrograms/h) over a 24-h period inhibited collagen-induced platelet aggregation. When biotinylated fibrinogen was injected intravenously into animals receiving Kistrin, megakaryocytes failed to endocytose the labeled fibrinogen. Endocytosis of fibrinogen into platelets was also inhibited in these animals. In contrast, platelets and megakaryocytes obtained from sham-infused control animals contained the injected biotinylated fibrinogen. We conclude that, in addition to the well-known extracellular function of cell adhesion, integrins can also act as receptors that mediate endocytosis of exogenous proteins and incorporate them into regulated secretory granules.

Animals↗
PubMed1992

Human fusion proteins between interleukin 2 and IgM heavy chain are cytotoxic for cells expressing the interleukin 2 receptor.

We have constructed a hybrid cDNA coding for a fusion protein between human interleukin 2 and a truncated heavy chain from human immunoglobulin M. The protein encoded by this cDNA contains the entire interleukin 2 sequence including its signal peptide, fused at its C terminus to domains 2 to 4 of the immunoglobulin heavy-chain constant region. Cells transfected with the hybrid cDNA secrete multimeric forms of the fusion protein, which bind specifically to cells bearing high-affinity interleukin 2 receptors. This binding leads either to T-cell proliferation or, if complement is added, to T-cell death. Multimeric forms of the fusion protein with a molecular mass above 500 kDa mediate complement-dependent lysis but trigger proliferation inefficiently when compared with forms with a low molecular mass (< 500 kDa). In contrast, the latter efficiently mediate T-cell proliferation without inducing complement-dependent lysis. The high molecular mass fusion proteins could thus constitute valuable tools for specific immunosuppression in humans.

Base Sequence↗
PubMed1992

Soluble interleukin 2 receptor (Tac chain) is not a reliable marker in kidney transplant recipient monitoring.

T lymphocyte expansion is triggered through interaction of interleukin 2 (IL-2) with its high-affinity receptor (IL-2R). This molecule is a heterodimer comprising an antigen-inducible component, the Tac chain (P55). Activation of T lymphocytes also generates a soluble form of this P55 called S-IL-2R. S-IL-2R is elevated in many T-cell-related pathologies (leukemia, autoimmunity, etc.). In graft recipients, rejection is a result of T-cell activation by graft antigens and therefore might induce a release of S-IL-2R in the circulation; this parameter is now said to be a good indicator of rejection. We have performed a study in renal graft recipients in order to assess the usefulness of circulating S-IL-2R particularly to discriminate the origin of renal failure in cases of rejection or of cyclosporin-A (CsA)-induced nephrotoxicity. We demonstrated that there are no differences between isolated values in the clinical groups at the time of diagnosis. Variations in S-IL-2R are increased compared to steady-state periods during rejection and cytomegalovirus infections, although not in CsA toxicity episodes. However, at the individual level there are too many false-positive and false-negative results, making this parameter no more meaningful than serum creatinine levels alone or even in association (as tested in logistic discriminant analysis). In addition, it seems that the variations in S-IL-2R are partly related to renal function itself, as suggested by the correlation between S-IL-2R levels and serum creatinine levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Biomarkers↗
PubMed1992

Follow-up of soluble interleukin-2 receptor levels after thymectomy in patients with myasthenia gravis.

Soluble interleukin-2 receptor (sIL-2R) levels were followed up after thymectomy by a quantitative immunoradiometric assay in 59 patients with myasthenia gravis (MG). Increased levels of sIL-2R were found in 30.5% of the patients before thymectomy. Serum levels were significantly higher in severely affected patients. Sequential sampling after thymectomy indicated a significant and progressive decline of sIL-2R levels within 2 years after surgery, which was well associated with clinical improvement or remission. The sIL-2R purified from sera of patients with MG had a molecular mass of 45 kDa as the normal sIL-2R. The decline after thymectomy of sIL-2R titers suggests a possible role of the thymus in the occurrence of sIL-2R in the periphery. Soluble IL-2R levels may represent a marker of disease severity in MG, which might be useful in the follow-up of individual patients.

Adolescent↗