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F Martinon

Publications and source records attributed to F Martinon.

At least 37 records · Page 2Linked to original sources
PubMed1996

Comparative efficiency of simple lipopeptide constructs for in vivo induction of virus-specific CTL.

We have previously shown that virus-specific CTL responses can be elicited in vivo by injecting, without adjuvant, 12-40 amino acid-long peptides, modified in C-terminal position by a simple lipidic amino acid. In this paper, we have studied the chemical accessibility, and the ability to induce in mice a CTL response, of a series of lipopeptides derived from the HIV-1 env (312-327) or (302-335) sequences. We showed that a single modification of these peptides by a lipidic amino acid, preferably in C-terminal position, results in the ability to reproducibly induce, without adjuvant, a relevant CTL response. No clear discrimination appeared concerning the nature of the lipidic modification. Our findings indicate that modification of a relatively long peptide by a N epsilon-palmitoyl-L-Lysylamide can be achieved by conventional methods of synthesis and characterization, offering the possibility to develop low-cost synthetic vaccines in models in which the CTL component is of importance.

Amino Acid Sequence↗
PubMed1995

Antigen-independent, integrin-mediated T cell activation.

The "outside-in" signals produced by the interaction of integrin molecules with the extracellular matrix (ECM) trigger a multitude of cellular events. The vitronectin receptor (VNR), an alpha v beta 3 heterodimer, functions as a costimulatory molecule for the activation of a subset of V gamma 1.1/C gamma 4-bearing gamma/delta T cells, which have been postulated to recognize a ubiquitous self-antigen. We addressed the question of whether stimulation of these T cells requires both engagement of the VNR by ECM proteins and engagement of the TCR by its Ag. We introduced into a TCR- but VNR+ mutant T cell hybridoma, TG40 (derived from 2B4), a chimeric molecule that contains the cytoplasmic tail of the TCR zeta-chain fused to the cytoplasmic and transmembrane region of either human CD8 or human CD25. The transfectants expressing the chimeric molecules secreted IL-2 constitutively when the VNR was engaged with a ligand, e.g., provided by ECM proteins present in FCS. This constitutive cytokine secretion could be blocked with mAb directed against the VNR, with or the peptide RGD, or by growth in serum-free medium. VNR-mediated cell activation also induced the phosphorylation of the zeta-chain. Signaling through the zeta-chain was required, as cells transfected with a chimera containing only a 22 amino-acid long, truncated zeta-chain did not secrete IL-2 constitutively. Thus, we demonstrated that the binding of the VNR to ECM protein in the presence of the zeta-chain is sufficient to induce cytokine secretion by T cells and does not require the recognition of an Ag by the TCR. Such integrin-mediated, Ag-independent activation of T cells may play a critical role in the potentiation of inflammatory responses.

Animals↗
PubMed1995

Pimelautide or trimexautide as built-in adjuvants associated with an HIV-1-derived peptide: synthesis and in vivo induction of antibody and virus-specific cytotoxic T-lymphocyte-mediated response.

Covalent association of lipopeptidic immunostimulants is known to improve the immunogenicity of short peptides. In this paper, we describe the synthesis of four analytically pure immunogens, prepared by two different strategies, in which a hexadecameric peptide (V3) derived from the principal neutralizing domain of HIV-1 envelope glycoprotein was associated with two different murein-derived lauroyl-peptides, Pimelautide (RP 44102), or Trimexautide (RP 56142). The in vivo immunogenicity of these compounds was evaluated according to two different criteria: the ability to elicit a cellular-T cytotoxic (CTL response) and the ability to stimulate antibody response. Our studies show that one of our compounds (TrxSucV3) was able to efficiently induce a relevant virus-specific CTL response, while another one (PimSucV3) was able to stimulate a strong antibody response to the linked peptide, or to a co-injected protein. These results suggest that both activities rely on different structure-activity relationships and that such a chemically defined model of peptide vaccines may be used to selectively stimulate subpopulations of immunocompetent cells.

Adjuvants, Immunologic↗
PubMed1995

Cells expressing a major histocompatibility complex class I molecule with a single covalently bound peptide are highly immunogenic.

The major histocompatibility complex (MHC) class I molecules expressed at the cell surface are associated with a large number of different peptides so that the density of a given MHC-peptide complex is relatively low. Here we describe the properties of MHC class I molecules genetically attached to a single antigenic peptide. Cells expressing these fusion proteins are recognized by T cells specific for the particular MHC-peptide complex. Coculture of naive splenocytes with cells expressing these MHC-peptide fusion proteins and the B7.1 antigen allows the induction of primary cytotoxic T lymphocytes (CTL) in vitro. Injection of these cells into naive mice enhances the frequency of specific CTL precursors and protects against a subsequent challenge with a tumor or a virus bearing the antigenic peptide. Soluble MHC-peptide fusions were also produced in which all three components, that is, the heavy chain, beta 2-microglobulin and the peptide, have fused into a single-chain protein. The availability of MHC class I molecules bound to a single peptide provides valuable tools for the manipulation of CTL responses and the analysis of the selection processes in the thymus.

Amino Acid Sequence↗
PubMed1995

Long-lasting anti-viral cytotoxic T lymphocytes induced in vivo with chimeric-multirestricted lipopeptides.

Cytotoxic T lymphocytes (CTL) play a major role in protective immunity against viral diseases. However, the antigenic formulations that can be used in vaccinations able to generate virus-specific CTL responses in vivo have yet to be defined. We have previously shown that HIV-1-specific CTL can be elicited in mice by injecting without adjuvant a synthetic peptide of the envelope glycoprotein that has been modified by the addition of a simple lipid tail to the end of the sequence (lipopeptide). The present study set out to address the question of whether such immunogens may be appropriate for preparing a human synthetic vaccine. We first showed that CTL were effectively induced by lipopeptides when given s.c. or i.p. We evidenced that the in vivo induction required stimulation of a concomitant specific T helper cell response, implying the presence of at least one CD4 epitope in the synthetic sequence used. Bearing in mind the particular properties that would be required in a prospective human peptide vaccine, we conceived a strategy in which a virus-specific CTL response could be generated in mice of different haplotypes using a single lipopeptide. We therefore tested a lipopeptide construct that integrated a synthetic sequence having three colinear epitopes of the influenza virus nucleoprotein, each restricted to a different H-2 haplotype. We found that a CTL response could be elicited to all three epitopes of this chimeric multirestricted lipopeptide construct. Finally, we have attempted to estimate the duration of the responses; strong CTL activities were still present up to six months after the last injection. These findings indicate that this approach may be suitable for developing a synthetic vaccine for human use.

Animals↗
PubMed1993

T cell receptor selection by and recognition of two class I major histocompatibility complex-restricted antigenic peptides that differ at a single position.

Peptides derived from HLA-Cw3 and HLA-A24 within region 170-179 differ by a single substitution, at position 173, and are both presented by the class I major histocompatibility complex molecule H-2Kd for recognition by murine cytolytic T lymphocytes (CTLs). As a first approach to understand the way T cell receptors (TCRs) intact with the HLA peptides, we have analyzed the TCR selection by, and recognition of, the two HLA antigenic sites. First, we have compared the TCR repertoires selected by HLA-Cw3 and HLA-A24, not only by sequencing the TCRs carried by CTL clones isolated and grown in vitro, but also by analyzing the TCRs expressed in vivo by peritoneal exudate lymphocytes from immune animals. Second, we have compared the TCR crossrecognition of HLA-A24 by CTLs selected by HLA-Cw3 with that of HLA-Cw3 by CTLs selected by HLA-A24. The combined analysis of TCR selection by and recognition of these two related HLA antigenic sites provides evidence that the TCR beta junctional regions interact with the amino-terminal part of the HLA peptides.

Amino Acid Sequence↗
PubMed1993

Induction of virus-specific cytotoxic T lymphocytes in vivo by liposome-entrapped mRNA.

The induction of anti-influenza cytotoxic T lymphocytes (CTL) in vivo by immunizing mice with liposomes containing messenger RNA (mRNA) encoding the influenza virus nucleoprotein (NP) is described. NP mRNA, obtained by in vitro transcription, was encapsulated into simple cholesterol/phosphatidylcholine/phosphatidylserine liposomes by the detergent removal technique. The dependence of the route of mRNA-liposomes delivery on CTL induction was studied. The CTL induced were identical to those obtained in vivo with infectious virus in terms of specificity, lysing both peptide-sensitized and virus-infected targets. Furthermore, with the same mRNA-liposome preparation, virus-specific CTL responses could be also elicited in mice of three different haplotypes each of them known to present a distinct NP peptide in an MHC-restricted fashion. The relevance of these results in the context of vaccine development is discussed.

Animals↗
PubMed1992

Immunization of mice with lipopeptides bypasses the prerequisite for adjuvant. Immune response of BALB/c mice to human immunodeficiency virus envelope glycoprotein.

In vivo priming of CTL requires the association with MHC class I molecules of peptides derived from the processing of endogenously produced proteins. Immunization with exogenous proteins or peptides rarely induces MHC class I-restricted CTL unless they are associated with lipidic compounds. The capacity to induce CTL was compared in synthetic peptides and simple lipopeptides containing the Immunodominant MHC class I H-2Dd-restricted T-cell epitope of HIV-1 gp160. In contrast with free peptides in saline, lipopeptides induced strong primary CTL responses in vivo. These CTL were able to lyse cells infected with a recombinant vaccinia virus expressing the HIV-1 env gene. Priming of CTL was also successful when using 16-amino acid lipopeptides as 34-amino acid lipopeptides, suggesting that several epitopes might be included in a single construct. In vivo priming of CTL also requires CD4+ T cell help. We therefore searched for Th cell activation after priming with lipopeptides. Our results show that, as with CTL induction, Th cell activation with lipopeptides did not require mixing with adjuvant. In addition, lipopeptides were also efficient at stimulating antibody-mediated responses. Our results show that a single lipopeptidic construct can induce a total immune response, which is of importance in vaccine development.

Adjuvants, Immunologic↗
PubMed1991

HLA-binding regions of HIV-1 proteins. I. Detection of seven HLA binding regions in the HIV-1 Nef protein.

The physical association of HLA class I or H-2 molecules with 36 HIV-1 Nef synthetic peptides was studied using a direct peptide binding assay (PBA) in solid phase. To assess the functional significance of the PBA results, the Nef peptides were also tested for their ability to inhibit the lytic activity of human or murine CTL. The PBA results showed that seven partly overlapping regions of the Nef protein contained MHC binding peptides (4-18, 46-67, 73-94, 100-128, 126-155, 182-198, and 192-206). Five of these seven regions included all the already described epitopes recognized by CD8+ human CTL. The two other regions, 4-18 and 46-67, are not yet described as antigenic for human CD8+ cells but they are located in the N-terminal part of Nef that was previously described as being stimulator for rat or chimpanzee CD4+ cells. Altogether, it can be concluded that 1) In virtually 100% of the cases, the PBA is capable to detect known antigenic peptides recognized by CTL. 2) The PBA and the functional inhibition assay provide similar results, supporting the functional significance of PBA results. 3) The PBA is easy to handle on a large scale, using multiple peptide and several MHC molecules, so that it can be used as a routine method for prevision of possibly epitopic sequences. 4) Systematic studies of peptides issued from the whole sequence of a given protein allow to map polyepitopic areas that are probably the most interesting parts of proteins for a vaccine purpose.

Amino Acid Sequence↗
PubMed1991

HLA-binding regions of HIV-1 proteins. II. A systematic study of viral proteins.

To detect HLA-binding peptides in 10 HIV-1 proteins (Rev, Tat, Vif, Vpr, Vpu, Gag p18, Gag p24, Gag p15, Env gp120 and Env gp41), the peptide binding assay (PBA) has been performed using three HLA class I molecules. Correlations have been searched between the PBA results and the peptide competitor activity in a functional test using HLA-A2-restricted CTL and target cells. A correlation between the data found in the PBA and well-defined CTL epitopes could be attempted only for the three Gag proteins. For these proteins, our results are in agreement with the known existence of epitopes reacting with human CD8+ CTL, with some exceptions. Together with the results reported with a panel of Nef peptides, these experiments showed that at least 18/20 of the already reported CTL epitopes from HIV-1 Gag, Nef, and Env proteins could be detected by the PBA, most (17/18) corresponding to strong reactivities. Perhaps more important, the regions of HIV-1 Gag p24 or Nef proteins that contain multiple associated CTL epitopes, with different HLA restrictions, were clearly identified by the reactivities in the PBA of several overlapping peptides and the major practical interest of the PBA might be the detection of such polyepitopic regions. Prediction are proposed in this report for 10 proteins, including several proteins for which CTL epitopes remain presently unknown.

Epitopes↗
PubMed1990

Analysis of physical interactions between peptides and HLA molecules and application to the detection of human immunodeficiency virus 1 antigenic peptides.

The physical association of 40 antigenic peptides and purified HLA class I and class II molecules was monitored using a direct peptide binding assay (PBA) in solid phase and an inhibition peptide binding assay (IPBA) in which the competing peptide was present in a soluble phase. We also examined the ability of different peptides to inhibit the lytic activity of human antiviral cytolytic T cells towards cells incubated with the corresponding target peptide. Our results showed that: (a) Binding of a given human T cell-recognized peptide to several HLA class I and class II molecules occurred frequently. Nevertheless, preferential binding of peptides to their respective restriction molecules was also observed. (b) Binding of HLA molecules to peptides recognized by murine T cells occurred less frequently. (c) 11 of 24 (46%) randomly selected HIV-1 peptides contained agretopic residues allowing their binding to HLA molecules. (d) The kinetics of HLA/peptide association depended on the peptide tested and were faster than or similar to those reported for Ia molecules. Dissociation of these complexes was very low. (e) Peptide/HLA molecule binding was dependent on length, number of positive charges, and presence of hydrophobic residue in the peptide. (f) A correlation was demonstrated between a peptide inhibitory effect in the IPBA and its blocking effect in the cytolytic test. Our data indicated that the restriction phenomenon observed in T cell responses was not strictly related to either an elective HLA/peptide association, or a high binding capacity of a peptide to HLA molecules. These data also showed that the PBA and IPBA are appropriate for the detection of agretopic residues within HIV-1 proteins.

Amino Acid Sequence↗
PubMed1990

In vitro human cytotoxic T cell responses against influenza A virus can be induced and selected by synthetic peptides.

Studies on human anti-influenza cytolytic activities have demonstrated that cytotoxic T lymphocytes (CTL) from HLA-B37 individuals react preferentially with the peptide corresponding to residues 335-349 of the nucleoprotein, whereas CTL from HLA-A2 donors recognize peptide 57-68 from the viral matrix as a dominant epitope. We studied the secondary CTL response, obtained from peripheral blood mononuclear cells, of an HLA-A2+,B37+ individual stimulated either by infectious virus or by synthetic peptides. Only an HLA-B37-restricted response was detected after stimulation by the whole virus, showing an immunodominance of this activity over that restricted by HLA-A2. Moreover, human cytotoxic cell lines were successfully obtained after stimulation of peripheral blood mononuclear cells with synthetic peptides. Under these conditions, it was possible to selectively reveal the existence of an HLA-A2-restricted activity directed against the matrix peptide. These results demonstrate that, at least in vitro, it is possible to stimulate a latent repertoire by using synthetic peptides. Nevertheless, we could not induce a response against the matrix or the nucleoprotein peptides in HLA-A2- or B37- individuals, suggesting that a finer selection of synthetic peptides would be necessary for their possible utilization to induce CTL during vaccination.

Amino Acid Sequence↗
PubMed1989

Physical association between MHC class I molecules and immunogenic peptides.

Antigenic peptides are presented to T lymphocytes by major histocompatibility complex (MHC) molecules. The binding of peptides to MHC class II molecules has been demonstrated directly, and is found to correlate with the ability of specific class II alleles to restrict the T-cell response to specific peptides. By comparison, a direct demonstration of a physical association between antigenic peptides and MHC class I molecules has proved difficult. A recent report shows that it is possible, however, and the three-dimensional structure of a class I MHC molecule illustrates the site where such binding must occur. Here we describe a simple assay which measures the binding of radiolabelled MHC class I molecules to peptides bound to a solid phase support. We find that class I molecules bind specifically to peptides known to be antigenic for class I-restricted cytotoxic T lymphocytes. Peptides which are recognized by cytotoxic T lymphocytes bind not only to the restricting MHC class I molecule but also to other class I molecules. Our results suggest that quantitative differences in the peptide/MHC class I interaction may influence the-pattern of MHC restriction observed in vivo.

Amino Acid Sequence↗
PubMed1989

Two epitopes and one agretope map to a single HLA-A2 peptide recognized by H-2-restricted T cells.

Mice immunized with syngeneic cells transfected with cloned genes coding for HLA class I molecules could recognize the human MHC Ag in the context of their own H-2 molecules. We obtained CTL clones from DBA/2 mice (H-2d) which had been immunized with P815 cells (a mastocytoma of DBA/2 origin) expressing either HLA-A2 or HLA-A3 or two different molecules containing recombined sequences of HLA-A2 and HLA-A3. Fourteen of these clones recognized a synthetic peptide corresponding to the region 170-185 of HLA-A2 in the context of H-2Kd. Moreover, from their activity on P815 cells expressing HLA-Cw3, two subpatterns could be distinguished: subpattern Cw3+, defined by those clones which lysed P815-Cw3, and subpattern Cw3- defined by those clones which did not lyse P815-Cw3. By testing the activity of clones of each subpattern on a series of modified synthetic peptides, we were able to define two epitopes on the same 170-185 peptide of HLA-A2. One of them was dependent on amino acids at positions 173 and 177, whereas the other was dependent on amino acid 177 alone. By using competition experiments, we were also able to define an agretopic region strongly dependent on the amino acid at position 178. Furthermore, experiments with L cells expressing molecules containing recombined sequences between H-2Kd and H-2Dd demonstrated the determinant role of residues 152, 155, and 156 from H-2Kd in the presentation to murine T cells of the 170-185 peptide of HLA-A2.

Amino Acid Sequence↗
PubMed1987

In vitro proliferation of human lymphocytes measured by an enzyme immunoassay using an anti-5-bromo-2-deoxyuridine monoclonal antibody.

A previously described, non radioactive method for the measure of in vitro mouse lymphocyte proliferation was applied to human lymphocyte proliferation assays. It involved incorporation into DNA, during cell multiplication, of 5-bromo-2-deoxyuridine (BUdR), a thymidine analogue. BUdR-DNA was then assayed by a sandwich enzyme immunoassay (BUdR-EIA) using an anti-BUdR monoclonal antibody (McAb 76-7). BUdR-DNA from crude cell extracts was first immobilized on microtitration plates coated with McAb 76-7. In a second step BUdR-DNA was reacted again with McAb 76-7 conjugated to horse radish peroxydase. The quantity of peroxydase in microtitration wells was then measured by the coloration of o-phenylenediamine (492 nm). Titration curves obtained with dilutions of crude extracts were compared to the curve obtained with a purified BUdR-DNA reference solution. Results were expressed as equivalent ng BUdR-DNA/ml. BUdR-EIA was compared to 3H-thymidine incorporating assay for the measure of lymphocyte proliferation induced by PHA mitogen, candidine and tuberculine antigens and mixed lymphocyte culture. Excellent correlation between both assays was observed for each experiments (r = 0.953 to 0.999). Overall correlation coefficient for the 5 experiments was 0.785, indicating greater variation of BUdR than 3H-thymidine incorporation, according to the mitogen or antigen used and the culture conditions. This could be due to that fact that BUdR-EIA measured only BUdR incorporated into DNA, while 3H-thymidine incorporation assay measured 3H-thymidine both incorporated into DNA, and stocked into the cell before DNA incorporation. BUdR-EIA would thus reflect cell proliferation more exactly than 3H-thymidine incorporation assay. The sensitivities of both techniques were comparable.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Monoclonal↗
PubMed1979

[Caecal lymphosarcoma. Prognostic and therapeutic interest of endoscopic diagnosis (author's transl)].

Primary lymphoreticulosarcomas aremare, scarely 0.3% of all malignant lesions of the digestive tract. Previously, only, slight clinical differences permitted differentiation before operation of this lesion from a common adenocarcinoma. Now the increasing use of colonic endoscopy permits one to determine preoperatively the lymphosarcomatous nature of a colonic tumour. Thus it is possible to carry out an appropriate preoperative assessment with lymphography and sternal marrow examination and also peroperative exploration with liver biopsy and lateral aortic lymph node biopsy. Treatment includes surgery, radiotherapy and chemotherapy, a more and more important place being reserved for the latter. Finally the recent histological classification of K. Lennert permits a more accurate prognosis.

Cecal Neoplasms↗
PubMed1978

[Surgery of obturator hernia by closure of the obturator canal with the round ligament].

Almost 2/3rds of obturator hernias occur after 70 years. Favoured by changes in pelvic and spinal position, this hernia is uncommon in women and exceptional in men. Revealed by strangulation, it is in one third to one quarter of cases, unrecognised before operation, often due to failure to recognise the cause of crural neuralgia in a patient with acute intestinal obstruction. Even when the diagnosis is made, laparotomy is the best approach. It makes intestinal resection easier, this is necessary in 50% of cases, and above all, it is easier to cure the hernia for which the authors propose the use of the round ligament folded on itself and fixed to the borders of the hernial orifice. Delay in treatment explains the high mortality in this rare hernia.

Adnexa Uteri↗