Biomedical subjects

C Daian

Publications and source records attributed to C Daian.

8 recordsLinked to original sources

PubMed1995

Derivatization with monomethoxypolyethylene glycol of Igs expressing viral epitopes obviates adjuvant requirements.

Ig molecules expressing within the CDR3 loop viral B or T cell epitopes were derivatized with mPEG 5,000. Pegylated Ig were used to investigate the in vitro and in vivo effect of pegylation on the immunogenicity of viral epitopes expressed in chimeric Ig. Two chimeras were used in this study: Ig-HA carrying a CD4 epitope corresponding to amino acid residues 110-120 of the hemagglutinin (HA) of PR8 influenza A virus and Ig-V3C, a murine-human chimera carrying a consensus B cell epitope from the V3 loop of HIV-1 gp120 protein. Pegylated Ig-HA (Ig-HA-mPEG) with 6 to 8% substituted lysine residues showed in vivo resistance to enzymatic degradation and persisted significantly in blood circulation and lymphoid organs. Moreover, Ig-HA-mPEG was able to activate in vitro HA110-120-specific hybridoma T cells and to prime T cell proliferative response in vivo without requirement for adjuvant. Also, mildly pegylated Ig-V3C (Ig-V3C-mPEG) administered into BALB/c mice in the absence of adjuvant induced specific Ab response to V3C peptide with insignificant response to xenogeneic human Ig determinants.

Adjuvants, Immunologic↗

PubMed1995

Induction of antibodies to the human immunodeficiency virus type 1 by immunization of baboons with immunoglobulin molecules carrying the principal neutralizing determinant of the envelope protein.

The hypervariable region 3 (V3) within the disulfide-bridged loop of the envelope protein of the human immunodeficiency virus type 1 (HIV-1) contains an amino acid sequence that was defined as a principal neutralizing determinant (PND). A 19-amino acid residue consensus sequence (designated V3C) predicted from the PND sequences of 245 isolates as well as a sequence from the PND of the WMJ2 HIV-1 isolate (designated V3M) were expressed on the variable region of murine-human immunoglobulin (Ig) chimeras that were designated Ig-V3C and Ig-V3M, respectively. The HIV-1 sequences on the Ig chimeras preserved their antigenicity and interacted with antibodies specific for peptides encompassing the V3C and V3M sequences. In baboons, Ig-V3C and Ig-V3M induced antibodies that bound V3C and V3M peptides as well as the glycoprotein gp120 envelope protein of HIV-1 MN isolate. In addition, the baboons' antisera were able to prevent infection of CD4 SupT1 susceptible T cells by HIV-1 MN. Finally, Ig-V3M chimeras were able to stimulate in vitro production of antibodies specific for the HIV-1 envelope-derived peptides by lymphocytes from HIV-1-infected human subjects.

AIDS Vaccines↗

PubMed1993

Induction of skin fibrosis and autoantibodies by infusion of immunocompetent cells from tight skin mice into C57BL/6 Pa/Pa mice.

Tight skin (TSK/+) mice develop a cutaneous hyperplasia associated with the occurrence of autoantibodies characteristic for scleroderma. In order to study the role of autoimmunity in the production of skin fibrosis, we conducted adoptive transfer experiments in which bone marrow cells of TSK/pa mice were infused into pa/pa mice littermates. (C57BL/6 pa/pa mice are used to produce heterozygous TSK/pa mice). Our results showed that after a prodromal period of several months, the transfer of bone marrow cells led to skin fibrosis, the presence of autoantibodies, and increased transcription of (alpha 1) collagen I and TGF beta genes. Infusion of enriched B or T cells alone did not cause skin fibrosis but of B cells alone increased autoantibody production. By contrast, transfer of T and B lymphocytes led to earlier mild fibrosis, cellular infiltration and autoantibody production as well as increased transcription of the (alpha 1) collagen gene. Our results strongly demonstrate, for the first time, that immunocompetent cells can play a role in the activation of collagen synthesis leading to skin fibrosis.

Animals↗

PubMed1993

Tight-skin mouse autoantibody repertoire: analysis of VH and VK gene usage.

In the previous studies we have shown that tight-skin (TSK) mouse is an experimental model for systemic sclerosis. This mutant mouse develops autoantibodies specific for scleroderma target antigens. To determine whether the expansion of autoantibody repertoire in TSK mouse occurs by selective expansion of certain variable region gene families, and whether CD5+ B cells contribute significantly to the production of autoantibodies, we have analyzed a panel of 60 hybridomas producing autoantibodies specific for scleroderma target autoantigens. Northern analysis of RNAs from these hybridomas showed that 70% were expressing genes from VHJ558 family while genes from 36-09 and J606 families were not at all represented. In contrast, in the cDNA libraries derived from splenic B cells, the expression of VHJ558 and 36-09 gene families were at an expected frequency corresponding to their genomic complexity (44% and 11.6%, respectively). These results demonstrate that there is a strong bias toward the use of J558 genes in TSK mouse autoantibody repertoire. On the other hand the expression of VK gene families was mostly random and corresponded to their frequency in splenic C kappa cDNA library. The pairing of VH:VK genes was stochastic. Analysis of the expression of J segments, however, revealed that JH2 and JK2 were predominantly used in the autoantibodies. Analysis of the expression CD5 mRNA in these hybridomas indicate that CD5+ B cells do not contribute significantly to the autoimmunity in TSK mice. These findings suggest that the expansion of peripheral autoreactive B cells in TSK mouse is determined by their immunoglobulin variable region rather than the genetic properties linked to a particular B cell subset.

Animals↗

PubMed1993

Engineered immunoglobulin molecules as vehicles for T cell epitopes.

The variable regions (V) of immunoglobulins (Ig) bear antigenic determinants that can stimulate both humoral and cellular immune responses subsequent to hetero, allo or iso-immunization. The expression of these determinants by Igs usually correlates with the presence of specific amino acid residues within the CDR loops of the V regions. Since the CDR loops varies in length, we reasoned that they would represent permissive sites to insert foreign peptides and create antigenized Igs expressing selected determinants. Taking advantage of these properties and the fact that Igs are self and long-lived molecules, we expressed a CTL and a helper epitope of influenza virus nucleoprotein and hemagglutinin respectively, within the heavy chain CDR3 loop of an anti-arsonate antibody. We found that foreign peptides comprised of 11 to 15 amino acid residues can be expressed within the V region of the heavy chain without alteration of pairing with the light chain. More striking, the cellular processing machinery is able to generate the peptides from the Ig context which were then recognized by specific T cells. Furthermore, the engineered Igs are able to induce T cell responses specific for the inserted peptide and for influenza virus. The use of engineered Ig molecules as vehicles for T and B cell peptides might represent a valuable strategy to generate safe, long lived reagents able to stimulate strong specific immune responses. This would then overcome the short half life of synthetic peptides based vaccines and the side effects seen in case of recombinant viral proteins or inactivated viruses based vaccines.

Animals↗

PubMed1992

Self-reactive repertoire of tight skin (TSK/+) mouse: immunochemical and molecular characterization of anti-cellular autoantibodies.

The tight skin (TSK/+) mouse has been proposed as an experimental model for progressive systemic sclerosis because of the biochemical alterations in collagen synthesis and pathological similarities to the human disease. Here, we report the analysis of tight skin mice sera for the presence of anti-cytoplasmic and anti-nuclear autoantibodies and determination of the frequency of hybridomas producing anti-cellular autoantibodies. The binding specificity of TSK mAbs to nuclear and cytoplasmic antigens such as keratin, actin, vimentin, and mitochondria was determined. Of 71 monoclonal antibodies that we have studied, only 3 appear to bind to foreign as well as self-antigens, indicating that the majority of these antibodies do not belong to the class of natural autoantibodies. Our results also showed that the frequency of hybridomas producing anti-nuclear and anti-cytoplasmic antibodies was higher in TSK mice than in C57BL/6 pa/pa, the control mouse strain, used in these studies. The results of the analysis of V gene usage showed that the majority of anti-cytoplasmic and anti-nuclear antibodies are encoded by genes from a restricted number of VH and VK genes families. In the sera of TSK mice we have detected the presence autoantibodies specific for cytoplasmic antigens in addition to anti-nuclear and anti-topoisomerase I antibodies which are characteristic of scleroderma. Since the presence of anti-cytoplasmic antibodies has not been described in scleroderma, the significance of their production in tight skin mice is not clear. However, the presence of such autoantibodies in the animal model provides a basis for investigation of this type of antibodies in human disease.

Actins↗

PubMed1992

A single amino acid mutation in CDR3 of the 3-14-9 L chain abolished expression of the IDA 10-defined idiotope and antigen binding.

The ABPC 48 myeloma protein and the 3-14-9 mAb derive their V region genes from the same VH and V kappa gene families. They also share a cross-reactive idiotope defined by the anti-Id mAb IDA 10. Whereas ABPC 48 is specific for bacterial levan, 3-14-9 showed a significant Ag-binding activity to aminophenyl-beta-N-acetylglucosaminide (AZO). In order to define the molecular basis of idiotope expression and Ag-binding activity, we have cloned the genes encoding the 3-14-9 H and L chain V region genes, generated antibodies that carry mutations within the L chain genes, by site-directed mutagenesis, and investigated the effects of those mutations with respect to IDA 10 idiotope expression and binding to AZO. Our findings show that, whereas expression of the IDA 10-defined idiotope requires association of both the H and L chains, a single change (glycine to phenylalanine) at position 91 in the third complementarity-determining region of the L chain abolished both idiotope expression and Ag-binding activity. In addition, a L chain change of alanine to threonine at position 25 allowed idiotope expression to some extent but significantly reduced binding activity to AZO. These data suggest that a single amino acid change can play a crucial role in the functional activity and structural integrity of antibodies.

Animals↗

PubMed1991

[Sudden death in acute myocardial infarct in hospitalized patients: a clinical and anatomicopathological study over a 10.5-year period].

The paper reports on the study of 1457 patients with acute myocardial infarct (Ami) admitted in the word of the cardiac intensive care of the clinic for 10.5 years. The general mortality was of 21.2% and the sudden death (defined as such when appeared suddenly within less than 1 hour from the onset of the acute symptoms, but after 24 hours from the onset of AMI in a patient apparently equilibrated) appeared in 114 patients who were examined postmortem (43.3% of the total of the deaths). The main causes of the SD was rupture of the myocardium (28.8% of the general mortality), primary ventricular fibrillation (22.0%) and thromboembolic phenomena (17.8%). The sudden death by rupture of the myocardium appeared in a first AMI, usually large and was not helped by the anticoagulant treatment or by other therapy. Primary ventricular fibrillation appeared during the first week from the onset and was favoured by the ventricular hyperexcitability and active myocardial ischemia (which were not specific). Xyline (only more than 2 mg/min) and amiodarone gave a good protection. The sudden death by systemic thromboembolization appeared almost only in the antero-lateral myocardial infarcts, 5-8 days after the onset. The appearance of a small flow syndrome "sine materia" with or without association of some recurrent arrhythmias was suggested. Efficient anticoagulation prevented systemic thromboembolization and, to a smaller extent to pulmonary thromboembolization.

Cause of Death↗