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M Fougereau

Publications and source records attributed to M Fougereau.

102 records · Page 6Linked to original sources
PubMedDate not supplied

Molecular polymorphism of various HLA-D subregions and rheumatoid arthritis.

In Caucasian populations, rheumatoid arthritis (RA) is generally associated with serologic HLA-DR4 specificity. In order to refine this correlation in the HLA-D region, we used six different probes pertaining to this locus: DR beta, DQ beta, DQ alpha, DO beta, DP beta and DP alpha. In this step, pooled RA and control DNA were hybridized with DR beta and DQ beta probes after digestion with 12 different endonucleases. Some bands appeared specific in the RA pool. In fact, with genomic DNA from 13 unrelated typed RA patients and 12 matched or partially matched control cells, these bands were revealed to be related to DR4 and/or DR1, with DR beta and DQ beta probes hybridizing BamHI, EcoRV, PvuII and StuI digests. With other probes, no differences could be related to RA disease. The polymorphism detected by these probes was suggestive of a gradient of decreasing complexity from DR beta to DO beta through DQ beta and DP beta, which could reflect discrete functions of each subregion.

Arthritis, Rheumatoid↗
PubMedDate not supplied

Interrelationships among distinct idiotypic specificities.

The fine idiotypic properties of a hybridoma (H51.85.2) anti-GAT antibody which lacks both CGAT and GA-1 idiotypes are described. We identified another idiotype, termed GA-2 idiotype, on H51.85.2 hybridoma antibody. The GA-2 idiotype is present in all mouse strains tested and is induced by GA-related antigenic determinants. An interesting relationship between GA-1 and GA-2 idiotype on hybridoma anti-GA antibodies was observed. All GA-1+ hybridomas also express GA-2 idiotype. In contrast, GA-2+ hybridomas can express a full set, a fraction, or none of the GA-1 idiotypic determinants. The data together with previous amino acid sequence studies strongly suggest that H51.85.2 hybridoma antibody was derived from the same VH and VL genes encoding the GA-1+ hybridoma antibodies.

Amino Acid Sequence↗
PubMedDate not supplied

Molecular analysis of the anti-GAT repertoire in three strains of mice.

GAT-specific antibodies which express the CGAT (or pGAT) public idiotypic specificities are encoded by a paucigene system. Antibodies expressing discrete specificities, i.e. anti-GAT and anti-NP, appeared to use the same VH germ-line genes, an observation which directly supports the importance of random H-L pairing to generate a large number of distinct antibody molecules.

Amino Acid Sequence↗
PubMedDate not supplied

The internal image and the structural idiotypic network (Ab1, Ab2, Ab3) in the GAT system.

The GAT repertoire expressed at the different levels of the classical idiotypic cascade Ag----Ab1----Ab2----Ab3 has been analysed by direct nucleotide sequencing of H- and L-enriched mRNA. Ab1 and Ab3 expressing the major public idiotypes used similar, if not identical, VH and VK genes. The VH Ab3 of the Ab1 type (Ab1') appeared highly conserved. Ab2 also use a small number of germ-line genes. The D region of Ab2 is of particular interest since it contains either a Tyr-Tyr-Glu or a Glu-Glu-Tyr sequence, characteristic of the GAT major determinants. It is therefore suggested that this D region contains the internal image of the antigen. A large number of VH germ-line genes have been isolated and sequenced. They all pertain to the VH-II family, which contains a large number of members, some of them being very close in sequence.

Amino Acid Sequence↗
PubMedDate not supplied

A structural basis for the internal image in the idiotypic network: antibodies against synthetic Ab2-D regions cross-react with the original antigen.

In the idiotypic cascade initiated by the random terpolymer (Glu60Ala30Tyr10)n or "GAT", we have identified, in the D region of Ab2 antibodies, either Glu-Glu-Tyr or Tyr-Tyr-Glu sequences which mimic GAT immunodominant epitopes, thus suggesting a structural basis for the internal image. Peptides containing the two D-region characteristic sequences were then synthesized and coupled to BSA. In mice, they elicited antibodies, a fraction of which recognized GAT. These observations speak in favour of the localization of an internal image of the GAT antigen in the D region of Ab2 antibodies.

Amino Acid Sequence↗
PubMedDate not supplied

Molecular interactions in the "GAT" idiotypic network: an approach using synthetic peptides.

In order to approach some of the dominant epitopes which are recognized in the GAT (Glu60 Ala30Tyr10)n random terpolymer, a variety of peptides containing 7 to 14 residues were synthesized using glutamic acid and tyrosine as building blocks, and thus were able to mimic determinants common to GAT and GT (Glu50Tyr50)n. One decapeptide and on dodecapeptide were found to inhibit GT-mAb1 (or mAb1') binding to the same extent as GAT. Antibodies were also raised against synthetic peptides which reproduced the sequence of the 6 CDR of the germline anti-GAT Ab1 antibody. Antibodies were obtained against all peptides except L1, and were shown to recognize the native Ab1-Fab. Surprisingly, some of these antibodies also recognized GAT, i.e. anti-L2, anti-H2 and anti-H3, an observation which speaks in favour of a triggering of the idiotypic network at the Ab3 level. Finally, a monoclonal antibody derived from an immunization with an Ab2-D region synthetic peptide was found to be of the Ag+Id- type. Sequence data indicate that the light chain at least is completely different from that the of Ab1/Ab1', which uses only a very precise pair of V germline genes.

Animals↗
PubMedDate not supplied

Two monoclonal antibodies against different antigens using the same VH germ-line gene.

Immunoglobulin diversity seems to arise largely by three mechanisms: (1) the existence of several germ-line genes, which must be rearranged before expression--that is, V and J for the light (L) chains, V, D and J for the heavy (H) chains; (2) somatic events, including mutations and gene conversion; and (3) combinatorial association of heavy and light chains, leading to the proposal that random pairing of p X H and q X L chains might generate p X q antibody molecules expressing discrete specificities. As heavy and light chains derived from the same immunoglobulin molecule would frequently reassociate preferentially, it is likely that only a fraction of potential heavy--light pairs actually provides "valid' antibodies. As a consequence of combinatorial heavy--light chain pairing, antibodies of discrete specificities sharing the same VH region, associated with distinct light chains (or vice versa) should be encountered. We report here that two heavy chains, derived from the same VH germ-line gene, may be present in anti-NP or anti--GAT antibodies, depending on their association with a specific lambda or kappa light chain, respectively.

Amino Acid Sequence↗
PubMedDate not supplied

Structural and functional mapping of immunoglobulin V-regions.

V-regions of immunoglobulins chains contain 3 types of positions, which are equally represented: invariant and sub-group characteristic, which account for the "framework" and hypervariable positions, responsible for antigen recognition. The 3 types of positions are grouped and fall within a very few discrete stretches. Sub-group characteristic segments containing one of the 2 cysteyl residues of the V-regions may be isolated by high voltage paper electrophoresis and provide a basis to type for sub-groups in the VK and in the VH human systems. This allowed to characterize a large set of human myeloma proteins that were used in a series of competitive hybridizations which indicated that sub-groups had no influence on preferential reassociations, which occurred in 80% of the cases. This preference seems to rely mostly on individual structural differences, which may be linked to heterogeneity at the framework level. Distinction between framework heterogeneity and hypervariable regions heterogeneity may be approached by raising antibodies against a mouse myeloma protein, MOPC 173, of known sequence, by means of syngeneic and allogeneic immunizations, using Balb/c and A/J mice. Junction of distinct portions of immunoglobulin chains such as the V and the C regions raises the possibility that some recognition signals may operate at the DNA level. Since rotational symmetry regions in the DNA are known to act as such signals, it is discussed whether such regions can be expected from the amino acid sequence data, especially in the vicinity of the "switch" peptide.

Amino Acid Sequence↗
PubMedDate not supplied

Partial structure of a rat IgD molecule with a deletion in the heavy chain.

The isolation, purification and characterization of the rat IR-731 monoclonal immunoglobulin is reported. The molecule is IgD-like, as appreciated from immunochemical and biochemical characteristics. H and L chains, Fab and Fc tryptic fragments have been isolated, analyzed, and partial sequence data have been obtained, including most cysteyl-containing peptides. The heavy chain contains a deletion which encompasses most of the CH2 domain and the beginning of the CH2 domain, and observation which does not reflect the intron-exon organization depicted for some murine heavy chains at the gene level. Basic structural features of the hinge region of the IgD molecule (extreme susceptibility to proteolytic enzymes, presence of basic amino acids near its COOH-terminus) have been found for the IR-731 molecule. In addition, partial sequence of the light chains points to the existence of K subgroups in the rat. Very limited amino acid changes have been identified in the K constant region, suggesting a possible--but limited--polymorphism which might be isotypic and/or allotypic in nature.

Amino Acid Sequence↗
PubMedDate not supplied

Structural basis for M-173 idiotypic determinants distinctively recognized in syngeneic and allogeneic immunization: contribution of DH, JH, and J kappa regions to an idiotope recognized by allogeneic antisera.

Antiidiotypic antibodies directed against the M-173 (IgG2a) mouse myeloma protein have been raised in syngeneic and allogeneic conditions. The antiidiotypic repertoires of several strains of mice have been compared by isoelectrofocusing, and a major idiotype has been identified by several antisera raised in allogeneic conditions in strains of mice which did not express the Igh-Ca allotype of the BALB background. Since this idiotype could be reformed in hybrid molecules containing the M-173 heavy chains and light chains which contained the J kappa 2 region, we propose that this determinant is dependent upon the J kappa 2, DH and JH regions, in addition, most probably, to a specific contribution of residues 45 and 54 of the heavy chains.

Amino Acid Sequence↗
PubMedDate not supplied

The complete sequence of the murine monoclonal immunoglobulin MOPC 173 (IgG2a): genetic implications.

The complete amino acid sequence of the murine monoclonal immunoglobulin MOPC 173 (IgG2a, kappa) is reported. The heavy chain contains 447 amino-acid residues, and one carbohydrate prosthetic group attached to the ASX residue 299. The kappa light chain is composed of 214 residues. The H chains are covalently linked by 3 interchain disulfide bridges. The H-L bond-forming cysteine of the H chain is between the VH and the CH1 domain. Intrachain bridges are disposed linearly, according to the classical model. There is no simple relationship between the primary structure and any given function of a particular domain. This is presumably due to the fact that the selection pressure exerts itself on the three-dimensional structure which may retain a conserved general organization as a result of balanced multiple mutations. Selection seems to act in two ways: --horizontally, in a multigene system such as the immunoglobulin classes (C domains of the heavy chains), leading to interclass homologies which are particularly marked for all the COOH-terminal domains of H and L chains which have, in addition a fair degree of homology with human beta2 microglobulin (about 30% identities); --vertically, in which case strictly homologous domains appear extremely conserved between distinct animal species. Conservation of the VH domains seems just as high as conservation of the CH domains. The VH region contains 3 types of positions: invariant and subgroup characteristic ("framework") which may be accounted for by a rather small number of germ-line genes, and hypervariable for which the origin of diversity, somatic or germinal, cannot be decided from sequence data alone. Murine VK domains, although basically built according to the same pattern, show a much more marked polymorphism of the framework, which might necessitate a higher number of basic germ-line genes. Finally, a hypothetical model of the switch mechanism is proposed. Rotational symmetry regions can be deduced at the DNA level from the known amino acid sequences of the switch peptides for the three translocational systems: H, kappa and lambda. These would provide recognition signals for restriction-like enzymes such as those which operate in prokaryotes. An implication of this model is the definition of an exact limit between the V and the C regions of all immunoglobulin chains.

Amino Acid Sequence↗