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Biomedical subjects

B Malissen

Publications and source records attributed to B Malissen.

At least 145 records · Page 8Linked to original sources
PubMed1983

Structural and genetic analyses of HLA class I molecules using monoclonal xenoantibodies.

The monoclonal antibodies B1.23.2 and B9.12 were developed to characterize human class I major histocompatibility gene products. They detect two different epitopes and define on a given lymphoblastoid B cell line two subsets of beta 2 microglobulin-complexed HLA class I molecules. One subset reacts with B9.12 and B1.23.2 and the other one expresses only the B9.12 epitope. Binding assays were performed on C3H mouse L cells which had been transformed with various single HLA-class I genes and the two detected molecular subsets were shown to be encoded by different genetic loci. Unlike B1.23.2, B9.12 detects all the beta 2m-complexed molecules expressed in human B cell lines and recognizes an epitope different from the one defined by W6/32. In contrast to the vast majority of the other reported anti-class I monoclonal antibodies (including B9.12), B1.23.2 recognizes an epitope expressed on both beta 2m-associated and -free HLA class I heavy chains.

Animals↗
PubMed1983

Transformation of murine LMTK- cells with purified HLA class I genes. I. Modification of conformation of murine beta 2-microglobulin upon its association with HLA heavy chains.

Murine LMTK- cells were unexpectedly found to cross-react with a murine anti-human beta 2-microglobulin (beta 2-m)monoclonal antibody (m.Ab) after transformation with cosmid clones containing different purified HLA class I genes. The same cross-reactivity was observed with CTP 34 B4 (murine x human) somatic hybrid cells, which express class I molecules constituted of human HLA heavy chains and murine beta 2-m. Inhibition studies of the complement-dependent cytolysis mediated by the cross-reacting m.Ab indicated that isolated murine beta 2-m does not express the cross-reacting determinant, suggesting that its expression by the transformed cells reflects conformational modification of murine beta 2-m upon its association with HLA heavy chains. These results illustrate one of the possible post-translational mechanisms through which the antigenicity of a polypeptide chain can be modified. They might provide a serologic marker of the third domain of HLA class I heavy chains. Finally, because quantitative differences of reactivity with the anti-human beta 2-m m.Ab were observed, depending on the HLA class I genes used for transformation, these results individualize two families of HLA class I heavy chains responsible for different conformational modifications of murine beta 2-m.

Animals↗
PubMed1982

Epitopic analysis of detergent-solubilized HLA molecules by solid-phase radioimmunoassay.

A solid-phase radioimmunoanalysis of plasma membrane molecules solubilized in the presence of detergent was developed. From a crude cell lysate, membrane molecules were specifically immobilized by solid-phase adsorbed monoclonal antibodies. Analysis of these molecules was easily performed with radiolabeled monoclonal antibodies of different specificities. This technique was used to analyze the HLA-DR and HLA-A,B,C molecules expressed by RAJI cells. It was possible (a) to determine which epitopes are expressed on the same molecules; (b) to define subsets of HLA molecules according to the epitopes which they express, and (c) to perform quantitative analysis of HLA molecules on a crude cell lysate.

Animals↗
PubMed1982

Human cytotoxic T cell structures associated with expression of cytolysis. I. Analysis at the clonal cell level of the cytolysis-inhibiting effect of 7 monoclonal antibodies.

Monoclonal antibodies (mAb) derived from BALB/c mice immunized with human anti-HLA-A2 cloned cytotoxic T lymphocytes (CTL) were screened for their ability to block, in the absence of complement, the cytolytic activity of the immunizing CTL clone. Eight cytolysis-inhibiting mAb have been derived. One of these was directed against a monomorphic determinant expressed on HLA-class I molecules and thus probably inhibited cytolysis via a target cell antigen-masking effect. The 7 other mAb recognized "CTL function-associated structures" and did not have to interfere with target cell antigens in order to inhibit cytolysis. F(ab')2 and Fab fragments of these 7 mAb were also inhibitory. Competitive inhibition of binding and preliminary biochemical analysis suggested that these 7 mAb defined on cloned CTL various epitopes of a structure of 30 kDa disulfide-bonded into several multimeric forms when analyzed without reduction. The inhibitory effect of these 7 mAb has been investigated on a series of short-term (1 month) and long-term (greater than 10 months) expanded cloned CTL lines derived in vitro from an in vivo allosensitized individual exhibiting various specificities. Unexpectedly, only 10% of these CTL clones were inhibited. Flow cytofluorimetric analysis further revealed that noninhibited and inhibited CTL clones expressed similar amounts of the 30-kDa structure. Consequently, the inhibition of CTL was heterogeneous when analyzed at the clonal level and not simply related to the presence or absence of this structure. Furthermore, the ability of CTL clones to be inhibited appeared to be unrelated to their HLA-A, B or C specificity or to their lytic activity. The connections between this mAb-defined structure and CTL function are discussed.

Animals↗
PubMed1982

Exon/intron organization and complete nucleotide sequence of an HLA gene.

We have isolated and determined the sequence of a genomic clone containing the gene for a human class I transplantation antigen. The gene contains seven exons. The first five exons code respectively for a signal peptide, for the first, second, and third extracellular domains of the protein molecule, and for the transmembrane region. The cytoplasmic segment is encoded by part of the fifth and the sixth and the seventh exons. The structure of the protein encoded by this unit is closely homologous with known class I transplantation antigens.

Bacteriophage lambda↗
PubMed1981

Expansion of human lymphocyte populations expressing specific immune reactivities. III. Specific colonies, either cytotoxic or proliferative, obtained from a population of responder cells primed in vitro. Preliminary immunogenetic analysis.

Human alloreactive cell lines were maintained in culture over prolonged periods of time using conditioned medium. Primed lymphocyte typing reactivity was observed in these T cell lines for only 1 mo, but these T cell lines have remained for more than 7 mo highly and specifically cytotoxic. Using as growth promoter an irradiated autologous feeder consisting of irradiated peripheral blood lymphocytes and the lectin leucoagglutinin, we have derived by limiting dilution cloning of in vitro primed allogeneic combinations, primary colonies (or primary clones) with monofunctional immune reactivities: either cytotoxic (the rarest observed) or PLT reactive (the majority of the colonies). Furthermore, each monofunctional primary colony when tested for PLT or CML reactivity on a panel of unrelated PBL, always showed a restricted specificity when compared to the original primed population. The PLT reactivity of each of the primary clones was short lasting in contrast to their growth potential. The CML reactivity of the primary clones, as for the T cell lines, was long lasting as was their growth potential.

Cells, Cultured↗
PubMed1981

Clones of human cytotoxic T lymphocytes derived from an allosensitized individual: HLA specificity and cell surface markers.

By planned immunization of a volunteer, two stable (greater than or equal to 6 months), specific, alloreactive cytolytic T-cell clones have been established from his peripheral blood lymphocytes. One clone reacts with all serologically defined HLA-Cw3 cells from our panel, whereas the other defines a split within the serological HLA-B40 specificity. The two cytotoxic clones are SmIg-negative, E-rosette positive, EA and EAC rosette-negative, HLA-A, -B and -C- positive, and also HLA-DR- or 'Ia like'-positive. In addition, they present very similar patterns of iodinated cell surface molecules as analysed by sodium dodecylsulphate polyacrylamide gel electrophoresis (SDS-PAGE), contrasting with that of an EBV cell line derived from the same donor.

Adult↗
PubMed1981

An antigenic determinant of human beta 2-microglobulin masked by the association with HLA heavy chains at the cell surface: analysis using monoclonal antibodies.

Four anti-human beta 2-microglobulin monoclonal antibodies were produced against whole lymphoid cells or against urinary beta 2-microglobulin. Their reactivity was fully inhibited by purified soluble beta 2-microglobulin. The B1.1G6, C23.24.2, and B2.62.2 antibodies bound either to free or to HLA-complexed beta 2m. They recognized the same or very close determinants, since they achieved mutual blocking. In contrast, the C21.48A1 antibody did not bind to the cell surface and did not recognize the same determinant on the purified beta 2-microglobulin molecule as the others. It was able to bind and to form a specific complex with membrane beta 2-microglobulin only, once separated from the HLA heavy chain. These data strongly suggest that the C21.48A1 antigenic determinant might be hidden when the beta 2-microglobulin is complexed with the HLA heavy chains at the cell surface.

Antibodies, Monoclonal↗
PubMed1981

Cross-reactions between mouse Ia and human HLA-D/DR antigens analyzed with monoclonal alloantibodies.

Two mouse monoclonal anti-I-E/Ck alloantibodies (H7-8.26 and H10-81.10) directed against 2 distinct determinants of the specificity Ia-7 and 1 anti-I-Ak alloantibody (H8-15.9) directed against a public determinant common to the I-A subregion products of the H-2k, H-2b, H-2d, H-2q, and H-2ja haplotypes identified cross-reactive determinants on lymphoid cells from various mammalian species, including rat, dog, pig, cow, hamster, and guinea pig. In man, these antibodies detected nonpolymorphic determinants of DR antigens on B cell-enriched peripheral blood lymphocytes from 50 unrelated individuals. These cross-reactive DR determinants were also detected on lymphoblastoid B cell lines, on PHA-activated peripheral T lymphocytes, and on allospecific cytolytic T cell clones, but not on various DR-negative human T leukemia cell lines. Two chains of 29,000 and 35,000 daltons m.w., corresponding to DR antigens, were precipitated by H7-8.26 and H8-15.9 antibodies from radiolabeled membrane extracts of Raji cells. Competitive binding experiments indicated that the 3 mouse anti-Iak antibodies identified 3 distinct cross-reactive determinants on human cells. The results indicate that: a) The cross-reactivity described between mouse I-E/C gene products (Ia-7) and human DR antigen(s) involves, in fact, several distinct and topologically distant determinants. b) At least 1 determinant cross-reacting with DR can be identified on I-Ak gene products. c) The intriguing genetic problem of mouse MHC allotypic determinant(s) being nonpolymorphic in man cannot be simply explained by the deletion of an I-E alpha chain in some strains of mice.

Absorption↗
PubMed1980

Production, expansion, and clonal analysis of T cells with specific HLA-restricted male lysis.

A cytotoxic T cell (CT) lines grown as a population (CT line) was initiated from the peripheral blood lympocytes (PBL) of a female aplastic anemia patient who was known to express CT that were able to lyse HLA-A2-positive male cells. The anti-H-Y HLA-A2-restricted cytotoxic activity could be maintained over prolonged periods of time. The CT lines could be expanded and maintained in culture for >65 d by the use of mitogens and irradiated feeder cells. Out of 68 cultures obtained after cloning of the CT lines, 43 showed varying, but always specific, anti-H-Y HLA-A2-restricted lytic capacity on a per-cell basis. We could show that the cloned cultures were composed of >80% T cells that carry the HLA-A, -B, -C, and also the HLA-DR antigens identical to the original PBL.

Anemia, Aplastic↗
PubMed1980

Expansion of human lymphocyte populations expressing specific immune reactivities. II. A comparison of immune reactivities in human T lymphocyte lines derived from allogeneically primed cultures and maintained with lectins or conditioned medium.

In a previous paper, lectins were shown to allow a strong expansion of in vitro primed cells; among the lectins tested, PKW but not PHA (nor Con A) was found to reactivate CTLs. We then asked two further questions: Could one maintain a long term expansion of human T cells using iterative lectin stimulation? And, if so, could the immune reactivities, once expressed in the original primed cells, also be maintained? We report here that lectins remain potent mitogens for primed cells, and allow good expansion over many cycles, provided fresh irradiated cells (autologous or not to the responder) are added to the cultures. When PKW is used as the iterative mitogen, both the specific proliferation (PLT) and the specific cytotoxicity are maintained after each cycle. When PHA is the iterative stimulant, only the specific proliferation (PLT) is maintained, while no measurable cytolysis is present. However, if iteratively PHA stimulated primed cells are now cultured in the absence of PHA, even without additional specific stimulation, cytolytic activity is recovered from the cultures. In parallel, primed cells iteratively expanded using conditioned medium appear to retain both their specific lytic function and their specific proliferative function. Preliminary data suggest that the cloning efficiency when using lectins is higher than when using conditioned medium.

Cells, Cultured↗