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C Le Guern

Publications and source records attributed to C Le Guern.

At least 19 recordsLinked to original sources
PubMed1987

Preliminary crystallographic study of a complex between the Fab fragment of a monoclonal anti-lysozyme antibody (D1.3) and the Fab fragment from an anti-idiotopic antibody against D1.3.

An anti-lysozyme antibody, D1.3, was used as immunogen to obtain syngeneic (Balb/c) monoclonal anti-idiotopic antibodies. The complex between Fab D1.3 and the Fab fragment from the anti-idiotopic antibody E225 has been crystallized. The crystals are monoclinic, space group P2(1), with a = 75.7 A, b = 77.4 A, c = 97.2 A, beta = 111.90 degrees and one molecule of the complex in the asymmetric unit. X-ray photographs show reflections extending to a resolution of about 3 A. Although twinning occurs frequently in the large crystals obtained, this material is suitable for high-resolution X-ray analysis.

Antibodies, Monoclonal↗
PubMed1987

Phorbol ester induces class II gene expression in pre-B cell lines.

The effect of phorbol myristate acetate on the induction of major histocompatibility complex class II gene expression was studied in four Abelson murine leukemia virus-transformed pre-B cell lines. In three cell lines, low concentrations of PMA (0.1-10 ng/ml) induced the expression of high levels of surface Ia molecules, and this effect was mediated at the transcriptional level. PMA induced a program of coordinated transcription of all four genes involved in the biosynthesis of Ia molecules. A spontaneous Ia-positive variant pre-B cell line was derived from an Ia-negative parental cell line. This variant was highly sensitive to the toxic effects of PMA, and highly responsive to the Ia-inductive effects of phorbol ester. Our findings suggest that in pre-B cells the appearance of Ia molecules and the regulation of their expression are controlled, at least partially, by variations in the activity of protein kinase C, which is the cellular receptor for phorbol esters.

Abelson murine leukemia virus↗
PubMed1987

Structure of a third murine immunoglobulin lambda light chain variable region that is expressed in laboratory mice.

Recently, we reported evidence for the existence of an immunoglobulin lambda light chain (lambda x) whose variable region differs from those encoded by the known V lambda gene segments V lambda 1 and V lambda 2. Expression of lambda x was detected in some hybridomas elicited by treatment of a BALB/c mouse with rabbit anti-lambda 2 antibodies coupled to bacterial lipopolysaccharide [Sanchez, P. & Cazenave, P.-A. (1987) J. Exp. Med. 166, 265-270]. We constructed a cDNA clone from one hybridoma (B6) that expresses the lambda x chain and determined the complete nucleotide sequence. The deduced amino acid sequence of V lambda x is 30-33% identical with those encoded by V lambda 1 and V lambda 2 and by V kappa gene segments. The third hypervariable region of V lambda x is four codons longer than those of the other murine variable gene segments. The expression of lambda x requires a genomic rearrangement that juxtaposes the V lambda x gene with the J lambda 2-C lambda 2 joining-constant gene pair. Rabbit anti-V lambda x antibodies detected the lambda x light chain in the normal sera of all laboratory mice tested. Lambda x expression seems to be independent of lambda 1 expression, since both SJL and SJA strains, which are defective in lambda 1 production, express normal levels of lambda x chain.

Amino Acid Sequence↗
PubMed1984

Inhibition of in vivo growth of murine plasmacytoma MOPC-460 by monoclonal anti-idiotypic antibodies directed at distinct idiotypes of the immunoglobulin on the surface of MOPC-460.

The effect of several well-characterized monoclonal anti-idiotypic antibodies on the in vivo growth of idiotype-bearing murine plasmacytoma cells was examined. They were chosen from a group of immunoglobulin G1 antibodies which react with the binding site determinants of M460, the immunoglobulin A dinitrophenyl-binding myeloma protein secreted by and present on the surface of MOPC-460, and included representatives of two families which recognize different determinants in the M460 variable region. The antibodies were administered daily, beginning 2 hr before i.v. tumor cell inoculation, and the effect on the appearance of tumor colony formation in the spleen was judged after 14 days. All four antibodies tested were inhibitory. At the highest doses used, the number of splenic tumor foci was reduced by up to 97%. The effect was highly specific since the growth of MOPC-315, which also produces an immunoglobulin A dinitrophenyl-binding myeloma protein, was unaffected by the antibodies, and a similarly prepared immunoglobulin G1 monoclonal antibody against an unrelated idiotype did not affect the growth of MOPC-460. The inhibition of tumor growth appears to be independent of complement and antibody-dependent cellular cytotoxicity mechanisms. A small fraction of clones escaping the antitumor effect of anti-idiotypic antibodies has stopped expressing the idiotype.

Animals↗
PubMed1983

Covalent coupling of antigens to chemically activated lipopolysaccharide: a tool for in vivo and in vitro specific B cell stimulation.

A simple chemical method is described which creates cyanate groups on the saccharide core of bacterial lipopolysaccharide (LPS). The activated LPS molecule is stable at pH 3.5 and can be kept for months at -20 degrees C without loss of properties. The strong reactivity of the cyanate groups permits efficient covalent coupling of various molecules to LPS. This is done under non-denaturing conditions. This paper also describes the coupling of microquantities of antigen (5-10 micrograms) to LPS. The 'LPS-antigen' conjugates are easily purified upon centrifugation at 15,000 X g. These compounds are mitogenic for B cells and trigger in vivo or in vitro production of antibodies directed against the coupled antigen. In vitro, a concentration of conjugate as low as 10(-2) micrograms/ml triggers specific antibody synthesis. Injection of 5 micrograms of conjugate in mice induces a humoral response detectable 7 days after immunization. B cells cultured for 5 days with an adequate dose of the LPS-beta-galactosidase conjugate were fused with the Sp2-0-Ag cell line to give anti-beta-galactosidase hybridomas.

Animals↗
PubMed1983

Incomplete expression of the MOPC 460 idiotype in the sera of BALB/c mice immunized either with DNP antigen or with anti-idiotypic antibodies.

The MOPC 460 idiotype, as defined by polyclonal probes, has been described as a recurrent marker among the anti-DNP antibodies synthetized by IghCa mice. In this paper, we demonstrate, using syngeneic monoclonal anti-idiotypic probes, that only a part of the idiotopes of this idiotype are indeed recurrently expressed in BALB/c mice (IghCa) after immunization with DNP antigen. We will also show that the immunization of BALB/c mice with monoclonal anti-idiotypic antibody specific for the recurrent determinant results firstly in the synthesis of anti-DNP antibodies and secondly in the expression of the same recurrent M460 idiotope present on a part of induced anti-DNP molecules. Contrary to this, the immunization with the monoclonal anti-idiotypic antibody specific for the private idiotope never resulted in the synthesis of anti-DNP antibodies. These results clearly suggest that, after DNP or anti-idiotypic immunization, the M460 idiotype is not expressed in its entirety.

Animals↗
PubMed1982

The relationship between variable region determinants and antigen specificity on mitogen reactive B cell subsets.

On the basis of previous frequency determinations we could set up large numbers of cultures, each containing less than one competent precursor B cell specific for beta-galactosidase or for each of three idiotopes previously found on a monoclonal anti-beta-galactosidase antibody. Cultures were polyclonally activated by either lipopolysaccharide or Nocardia-delipidated cell mitogen. Each culture supernatant was individually tested for hemagglutination activity against sheep erythrocytes coupled with beta-galactosidase or with each of the three purified monoclonal anti-idiotypic antibodies. The results showed that only a minority of those clones positive for only one or two idiotopes recognized antigen. However, all those clones simultaneously positive for the three V region determinants recognized beta-galactosidase. The implications of these results for our understanding of the relationship between the antigen-binding site and idiotope expression are discussed.

Animals↗
PubMed1982

Mitogen-reactive B cell subpopulations selectively express different sets of V regions.

The experiments presented here were designed to investigate whether the idiotypic repertoire is equally distributed among B cells subpopulations as defined by mitogen reactivity. To this end we used lipopolysaccharides (LPS) and Nocardia delipidated cell mitogens (NDCM), which are two mitogens that have been described to act on different B cell subsets. The repertoire can be defined in quantitative terms as the frequency of B cells that are precursors for clones secreting immunoglobulin with a given specificity or with a determinate idiotype. We determined, therefore, the absolute frequency of LPS- and NDCM-sensitive B lymphocytes secreting immunoglobulin molecules that bear three idiotopes originally found on a monoclonal anti-beta galactosidase antibody. Because the frequencies of B cells carrying one of these idiotypes are dramatically different in the LPS- and NDCM-sensitive B cells subsets, we conclude that the idiotypic repertoire is not randomly distributed among mitogen-reactive B cell subpopulations.

Animals↗
PubMed1982

Intrastrain recurrent idiotypes among anti-DNA antibodies of (NZB x NZW)F1 hybrid mice.

Immunization of NZB and A/J mice against an anti-DNA hybridoma antibody (F227) derived from (NZB x NZW)F1 (B/W) mice allowed the preparation of two anti-idiotypic antisera. These two reagents were shown to recognize different idiotopes of the F227 monoclonal antibody. NZB anti-idiotypic antibodies recognized non-ligand-modifiable idiotypic determinants. These idiotopes were private or present at undetectable level in BW mouse sera since it was found that only two of the 24 B/W mouse sera tested were recognized by these antibodies. Conversely, A/J anti-idiotypic antibodies recognized partially ligand-modifiable idiotopes which were found in all B/W mouse sera tested. These results demonstrate that anti-DNA antibodies share similar idiotypic specificities and suggest that these autoantibodies occur as families of structurally related proteins.

Animals↗
PubMed1982

Specificity and idiotypic analysis of monoclonal antibodies directed against the MOPC460 idiotype.

Eight syngeneic anti-idiotypic hybridomas (IDMs) have been obtained against the BALB/c myeloma protein MOPC460 which displays anti-TNP activity. The study of their anti-idiotype specificity allowed us to distinguish them into two groups which define the presence of at least two idiotypic determinants or idiotopes in the MOPC460 idiotype. The biochemical analysis of the monoclonal antibodies is consistent with this dichotomy. This analysis, in fact, showed a striking correlation between anti-idiotypic specificity and biochemical characteristics of the monoclonal antibodies. Consequently, the idiotypic specificities of three of these hybridomas were studied. In accordance with what is expected, our results clearly indicate a strong idiotypic similarity for hybridomas belonging to the same group and a lack of idiotypic cross-reactivity.

Animals↗
PubMed1982

A self determinant recognizing T cell hybridoma.

A T cell hybridoma (53(113)) obtained by fusion of BALB/c spleen cells and the BW 5147 lymphoma T cell line is described. This hybridoma recognizes mouse RBC (MRBC) and rat RBC, but not human, rabbit, guinea pig, or SRBC. The culture supernatant possesses hemagglutinating activity for the same indicator RBC. In addition to this, 53(113) cells are able to form protein A plaques in the presence of guinea pig complement and normal mouse serum (NMS) or purified mouse immunoglobulins (Ig). Because mouse Ig as well as sonicates from MRBC are able to inhibit the rosettes between the hybridoma cells and the MRBC, and because the sonicates inhibit protein A plaque formation, it seems likely that the same product can recognize a similar determinant expressed on MRBC and mouse Ig. The hypothesis that a 53(113) structure recognizes identical or cross-reactive carbohydrate determinants shared by murine Ig and C is considered.

Animals↗
PubMed1981

Recognition of MOPC-460 variable region determinants by polyclonally distributed triggering receptors on B lymphocytes.

Purified M460 protein-induced untreated and anti-Thy 1.2 and complement-treated murine spleen cells to proliferate and differentiate in vitro. Fc receptor complexing was not responsible for the phenomenon, since M460 Fab fragments retained the B cell triggering activity. Activation was inhibitable by the addition of DNP-glycine to cultures and could also be detected by using spleen cells from various strains of mice, including the C3H/HeJ, which is genetically nonresponding to LPS. Hybrid molecules were constructed between the M460 proteins and the products of 2 myelomas that do not activate B cells, namely, X25 and X24. The only hybrid molecules that retained triggering activity were (L460-Hx25)2. Interestingly, the same molecule was also the only one recognized by an anti-M460 monoclonal antibody (F6(51)) that has been previously shown to induce B cells to proliferate and differentiate. The data suggest the existence on B lymphocytes of a network of polyclonally distributed mitogen receptors that share determinants cross-reacting with immunoglobulin idiotypes.

Animals↗
PubMed1980

Idiotypic network: the MOPC 460 system.

The results presented in this communication show very clearly that the mice with IghCa haplotype can produce anti-TNP antibodies from which a fraction share the idiotypic determinants expressed on M460 myeloma protein. Nevertheless the gene(s) which encode(s) this specificity, is present in the repertoire of strains of mice which have not this haplotype. As in DBA/2 mice this silent clone(s) can be stimulated by an appropriate immunological manipulation and their progeny even can be frozen in hybridomas. The expression of 460 Id positive anti-TNP antibody forming cells is regulated by T cells in BALB/c mice. These T cells are specific for 460 Id and share the idiotypic determinants of anti-460 Id antibodies since they were not found in BALB/c mice with an Ab3 type of response.

Animals↗
PubMed1979

Immunocytochemical localization of a calcium-binding protein in the rat duodenum.

The cellular localization of the vitamin D-dependent calcium-binding protein (CaBP) in the duodenum of rat was studied using indirect immunofluorescence and immunoperoxidase-staining methods. Specific positive reaction product, indicative of the presence of CaBP, was exclusively located within the villous part of the duodenal mucosa. Moreover, CaBP was detected mainly within the supranuclear region of the cytoplasm of absorptive cells and also at the level of their basal laminae. CaBP was not demonstrable either in the nuclei or associated with the brush border membrane of absorptive cells. Also, CaBP was neither detectable in goblet cells nor in sub-epithelial layers. When the specific anti-CaBP antiserum was replaced by nonimmune rabbit serum or when it was preabsorbed on a CaBP-Sepharose conjugate, no positive immunostaining was seen. Together with recent biochemical data our observations agree well with the view that CaBP may act as an intracellular "buffer" by protecting the cell against too high Ca2+ concentrations.

Animals↗