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H Dastot

Publications and source records attributed to H Dastot.

17 recordsLinked to original sources
PubMed1992

Increased surface expression of a newly identified 150-kDa dimer early after human T lymphocyte activation.

Lymphocyte activation induces or increases the expression of several surface structures, some of which are directly involved in cell growth such as receptors for IL-2 or transferrin. In order to identify new structures characteristic of activated lymphocytes, we developed a series of mAb against functionally defined human T cell clones. In the present study we report the isolation of a mAb termed BB18 recognizing, at the cell surface, a novel 150-kDa glycoprotein dimer whose expression on T lymphocytes increases readily after their activation with various stimuli including lectins. In contrast, in the presence of PMA, cell-surface expression of this 150-kDa structure is down-regulated even earlier than CD3 molecules. Biochemical studies as well as phenotypic analysis revealed that this structure is different from all previously identified molecules on the lymphocyte cell surface. Furthermore, functional studies showed that triggering this disulfide-linked dimer through BB18 epitope in the presence of submitogenic concentrations of PMA induced strong lymphocyte proliferation. This proliferative response require E+ cells and accessory cells, and this even after immobilization of BB18 mAb.

Animals↗
PubMed1992

The CD39 molecule defines distinct cytotoxic subsets within alloactivated human CD8-positive cells.

Lymphocyte activation induces or increases the expression of several surface structures, none of which is characteristic of an activated cell subset. In particular, structures such as CD45RO, CD25, CD26, CD49b, CD54, CD71 are expressed by the vast majority of lymphocytes at various times following in vitro activation. CD39 molecules were originally identified on activated B lymphocytes and have recently been described on activated T cell clones. In the present report, we have characterized phenotypically and functionally defined cell subsets generated during an in vitro allostimulation. Results indicated that the percentage of CD39+ cells reached a maximum at day 6 and remained stable thereafter. We demonstrate that CD39 expression allows the identification within the allosensitized CD8+ cytotoxic cells of distinct subsets of cells mediating allo cytotoxic T lymphocyte or natural killer (NK)-like reactivity. More precisely, CD8+CD39+ alloactivated cells mainly mediate specific killer activity, whereas CD8+CD39- alloactivated cells predominantly exhibit NK-like reactivity. Further, we show a high functional correlation associated with the lack of CD39 expression on NK-like alloactivated CD8+ cells, while there is no association with CD56 or CD57 NK-associated structures.

Adenosine Triphosphatases↗
PubMed1990

In vitro differentiation from a pluripotent human CD4+CD8+ thymic cloned cell into four phenotypically distinct subsets.

Human thymic cell differentiation is almost totally unknown. In the present study we developed an in vitro system using human thymic cloned cells to analyze precursor-progeny relationship. We obtained several CD4+CD8+ double positive thymic clones that could give rise after several weeks in culture only to either CD4 or CD8 single positive clones. By contrast we isolated a unique pluripotent thymic double positive clone, termed B12, which differentiated into four phenotypically distinct T cell clones, namely double-positive CD4+CD8+, double-negative CD4-CD8- or either single-positive phenotype. We derived stable subclones representative of each phenotype and we showed by molecular analysis that they expressed the same TCR. Utilization of either CD3 or anticlonotypic mAb revealed that this TCR expressed by the four subclones was functional.

Antigens, CD↗
PubMed1990

Correlation between T cell receptor gamma delta isotypic forms and cytotoxic activity: analysis with human T cell clones and lines.

Three biochemically distinct isotypic forms of the human T cell receptor (TcR) gamma delta structure can be expressed at the cell membrane. This unique variation in structure of TcR, which is due to C gamma gene segments utilization, prompted us to look for isotype-association functional differences. In this regard, we have developed human T cell clones or lines from normal thymus or peripheral blood from several patients. In the present report, we have selected by phenotypic, biochemical, and TcR gene rearrangement analysis representative pairs of IL2-dependent clones or lines for each TcR gamma delta isotypic form. The results showed a lack of correlation between the TcR isotypes and the ability of the cells to proliferate in response to TcR stimulation mediated through the CD3 molecular complexes. By contrast, despite the fact that all of these representative cells exhibit an NK-like activity, as measured by their ability to kill K562, the strongest lytic activity was observed with the cells having the disulfide-bonded form of the receptor. Moreover only those latter cells were able to efficiently kill the LAK-sensitive Daudi cell line.

Clone Cells↗
PubMed1988

Intermolecular complexes between three human CD1 molecules on normal thymus cells.

The first cluster of differentiation (CD1) defines at least three distinct human thymic cell-surface differentiation antigens-CD1a, CD1b, and CD1c. We looked for structural homology of the three CD1 heavy chains at their peptide level by two-dimensional peptide maps. We show here that the CD1a Mr 49,000 heavy chain and the CD1b Mr 45,000 heavy chain appear to be more homologous to each other than to the CD1c Mr 43,000 heavy chain and that only one tyrosil peptide is common to the three heavy chains. Study of the CD1 heavy chains from several individuals reveals a very limited polymorphism of these molecules. We also demonstrate here that CD1a or CD1a-like molecules and other CD1 molecules can form intermolecular complexes on the surface of normal thymus cells. Molecules that are structurally very similar to CD1a molecules are associated noncovalently either with CD1c molecules or with CD1b molecules, and only CD1a molecules can associate covalently with CD8 molecules. In contrast, we could not find these intermolecular complexes on the surface of leukemic T-cell lines in culture.

Antibodies, Monoclonal↗
PubMed1988

HLA class I molecules are associated with CD1a heavy chains on normal human thymus cells.

The molecules encoded by the major histocompatibility complex play a pivotal role in regulatory interactions between cells of the immune system, which can result in the activation and function of T cells. The function of the CD1 molecules, which are homologous to the major histocompatibility complex-encoded molecules but are encoded on human chromosome 1, is not known. HLA class I molecules and CD1a heavy chains share the ability to associate with several different cell-surface molecules. We show here, by several technical approaches, that HLA class I molecules are associated with CD1a heavy chains on the surface of normal thymus cells. The functional significance of this association during T-cell differentiation is discussed.

Antibodies, Monoclonal↗
PubMed1987

Analysis of CD1 molecules on thymus cells and leukemic T lymphoblasts identifies discrete phenotypes and reveals that CD1 intermolecular complexes are observed only on normal cells.

We looked at the surface expression of the three distinct human thymic cell surface differentiation antigens, CD1a, CD1b, and CD1c, that presently define the first cluster of differentiation (CD) on the cells from 34 patients with acute T cell malignancies. We also studied the expression of other T cell-restricted molecules, including the T cell receptors, on these cells. Our results confirm the extensive phenotypic heterogeneity of the cells from acute T cell malignancies, which contrast with the more limited phenotypic diversity of subacute or chronic T cell malignancies. Our study of normal children and fetal thymus cells shows that the extensive phenotypic heterogeneity of the malignant cells reflects the heterogeneity of the thymic subpopulations and shows that most of the phenotypes observed on malignant T cells have a normal counterpart, particularly in the fetal thymus. Moreover, we demonstrate that the CD1a molecules, which can form three different types of noncovalent intermolecular complexes on the surface of normal thymus cells, do not form any noncovalent intermolecular complexes on the surface of leukemic cells. We also show that CD1a molecules can form covalent intermolecular complexes with CD8 molecules on some but not all malignant cells.

Antibodies, Monoclonal↗
PubMed1982

A new Epstein-Barr virus negative Burkitt's lymphoma derived cell-line. I. Analysis of cell surface markers and abnormal expression of HLA antigens.

CHEV, a new Epstein-Barr virus negative Burkitt's lymphoma derived cell line has been studied. Karyotype analyses demonstrated the t (8; 14) characteristic translocation. Cell surface characterisation of this line showed the presence of mu and chi immunoglobulin chains and beta 2-microglobulin and the absence of the complement receptor. We are unable to detect HLA--A, B alloantigens on the cell surface which was in contrast with an apparently normal expression of these antigens in the cytoplasm.

Antigens, Neoplasm↗
PubMed1977

HLA antigens in 16 families with xeroderma pigmentosum.

Xeroderma pigmentosum is an autosomal recessive disease. HLA-A and -B typing was performed on peripheral blood lymphocytes and platelets. Sixteen Tunisian families were typed with 37 patients and 108 relatives. Genetic transmission of the disease and of the HLA system seemed to be independent in this study. Comparison of HLA gene frequencies between (unrelated) parents of patients and a control population showed no difference, proving that there is no clear association in populations between deleterious XP genes and a particular HLA gene. However, an excess of identical HLA among pairs of diseased siblings would suggest that the disease is polymorphic and a form of the XP could be linked to HLA.

Blood Platelets↗
PubMed1975

The HL-A gene structure of Twareg populations. II. The Kel Dinig.

The HL-A groups of 138 Kel Diniq Twaregs were determined by the platelet complement fixation microtechnique. Their HL-A characteristics, compared to those of Caucasoid populations, are: decrease in HL-A2, 9, W17 and W15; increase in W28, W32, HL-A7, W5, W10 and second locus blank; absence of Da25 (W30 plus W31), HL-A13, W15, W18, W27. This genetic structure is in accordance with the isolated condition of this population. The most frequent haplotypes are W28,HL-A7, common to both the Kel Diniq and the Kel Kummer Twaregs previously studied; W32,W10 and HL-A3, HL-A5, Kel Diniq only. These two populations are both isolates, with a common origin the seventeenth century, but separated as from that date. Genealogical studies have enabled the haplotype W28,HL-A7 to be attributed to the two brothers who founded the populations in the seventeenth century. A comparison of these two populations constitutes a model for the study of genetic drift and the founder effect.

Complement Fixation Tests↗
PubMed1975

HL-A phenotyping in an Indonesian population.

The frequencies of 30 HL-A antigens were studied in an Indonesian population of 95 individuals from the city of Jakarta. The antigens HL-A9, or more precisely W24, and HL-A11 (first series) and W15 (second series) occurred with high frequencies, whereas HL-A8, W14 and W22 were completely absent. These results are consistent with previous reports of HL-A typing in South East Asian populations.

Complement Fixation Tests↗