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Biomedical subjects

L Degos

Publications and source records attributed to L Degos.

At least 181 records · Page 10Linked to original sources
PubMed1989

[Refractory anemia with partial blastosis. A new therapeutic approach].

Refractory anaemia with partial myeloblastosis is classified among myelodysplasia syndromes which are characterized by abnormalities in the differentiation of haematopoietic cells, but it differs from these syndromes in that blast cells are in excess and the prognosis is darker. So far, this type of anaemia has resisted all treatment. The possibility of differentiating leukaemic cells in vitro has opened new therapeutic prospects.

Aclarubicin↗
PubMed1989

alpha-IFN treatment does not induce Ki-ras expression in hairy-cell leukemia patients.

alpha-Interferon (IFN) is effective in the treatment of hairy-cell leukemia (HCL), but the treatment is sometimes over a long period. Biological changes such as the increase of tumorigenicity can occur rapidly in vivo as a result of beginning this treatment; an increase in c-Ki-ras oncogene expression has also been observed. In order to determine whether the findings observed in vitro would be duplicated in an in vivo system, we decided to analyze the Ki-ras RNA and protein levels in the lymphocytes of three HCL patients, compared with these levels in seven normal donors and one non-treated HCL patients. Ki-ras was not activated by IFN, at least not in lymphocytes. Therefore, the data suggest that the drug could be used for long-term therapy with relatively low risk to the patients.

Gene Expression Regulation↗
PubMed1989

HLA-DR and DQ antigens in chronic lymphocytic leukemia: dissociation of expression revealed by cell surface, protein, and mRNA studies.

We studied peripheral blood lymphocytes (PBL) of eight B chronic lymphocytic leukemia (CLL) patients for the expression of the human leucocyte antigens, HLA-DR and HLA-DQ. Cell surface expression of HLA class II epitopes was analyzed by fluorescent activated cell sorter (FACS) using three monomorphic anti-HLA class II monoclonal antibodies (mAb) specific for DR (D1.12) and DQ (TU22, L2) and a polymorphic anti-DQ (G2A5). The DR and DQ molecules were characterized by two-dimensional gel electrophoresis (2D-PAGE) of the specific immunoprecipitates from biosynthetically labeled cells. DR, DQ specific probes were used to characterize the class II transcripts of the corresponding genes. The data obtained with immunofluorescence disclosed two distinct patterns of HLA class II expression leading to two cell surface phenotypes: (DR+DQ+) and (DR+DQ-). In all cases the cells expressed normal amounts of HLA-DR gene products in terms of mRNA. DR cell surface determinants were present in more than 80% of cells in every sample. By 2-D gel analysis DR proteins disclosed the normal classical pattern associating the alpha, beta, and invariant chain gamma with normal level of biosynthesis for alpha and gamma but decreased biosynthesis for one of the beta gene products. Moreover, the three chains demonstrated defect in glycosylation process. In half of the cases studied the cells lacked DQ molecules at the cell surface. DQ alpha and DQ beta transcripts were detected in all cases, although the amount was extremely low in one case. DQ proteins were variable in the DQ+ phenotype and absent in the DQ- one. Interestingly, TPA and rIFN gamma treatment could restore normal glycosylation process of the DR isotype and increase biosynthesis of DQ alpha and beta chains. Those combined results support the view that transcriptional, post-transcriptional, and posttranslational mechanisms underlie the heterogeneity of class II expression observed in CLL. Moreover, 2-D gel analysis may be an invaluable tool for the analysis of the biosynthetic process of class II molecules.

Antigens, Surface↗
PubMed1989

TCR gamma delta bearing lymphocyte clones with lymphokine-activated killer activity against autologous leukemic cells.

Activated T lymphocytes with the T-cell receptor (TCR) gamma delta (CD3+ and TCR delta 1+) exhibit strong cytotoxic activity against the standard natural killer (NK) and lymphokine-activated killer (LAK) sensitive target cells. In order to test the cytotoxic activity of gamma delta T lymphocytes against autologous leukemic cells, 84 clones of gamma delta T lymphocytes were obtained from the peripheral blood of three acute lymphoblastic leukemia (ALL) patients. Forty-four of these T-cell clones were active against an LAK-sensitive cell line and the other 40 were active against K562, an NK target cell line. In each of the three patients, cytotoxic clones against autologous leukemic cells were obtained. Among the 84 clones, ten were able to kill autologous tumor cells, including eight that lyse the LAK-sensitive target and two with NK activity. The clones were highly cytotoxic, stable, and easily expanded in large quantity.

Adult↗
PubMed1989

Human CD3 gamma delta + activated lymphocytes exhibit killer activity in vitro against autologous leukemic cells.

TCR gamma delta expressing T cell clones are able to exhibit in vitro strong cytolytic activity against cultured tumor cell lines as the myeloid K562 or the Burkitt's lymphoma Daudi cell line. We investigate the possibility of developing TCR gamma delta bearing T cell lines from peripheral blood of 2 leukemic patients in complete remission in order to study their ability to kill autologous leukemic cells. T lymphocyte clones are obtained by limiting dilution of lymphocytes from the blood of patients with an acute lymphoblastic leukemia (ALL). The T cell clones are first selected for their CD8- CD4-phenotype and then for their ability to react with the monoclonal antibody anti-CD3 without presenting reactivity with a monoclonal antibody directed against the TCR alpha beta. Further biochemical studies have indicated that the CD3 associated structure expressed on the cell membrane of these T cell clones is a gamma delta heterodimer. Functional analysis have indicated that these cloned cells are able to kill in a classical cell mediated lysis assay the autologous leukemic cells only when also LAK activity is observed. Thanks to this clonal expansion 10(10) cells/week indefinitely only 1 sample of peripheral blood will be necessary. Would these results be found with other leukemic patients, we propose to use this procedure for a possible application of killer cells for maintenance therapy of leukemia.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1989

Hairy cell leukemia: follow-up after completion of alpha interferon treatment.

Between May 84 and December 85, 61 patients were treated for hairy cell leukemia by (recombinant or natural) alpha-IFN in a single institution. The responses obtained after 7 or 12 months of treatment are presented and the follow-up of the 39 patients for whom the treatment had been stopped for more than 12 months is evaluated. Neither clinical or histological parameters at presentation nor the type of timing of the interferon used allowed to predict the quality of response. The median time-lapse before the occurrence of neutropenia below 1.10(9)/l in patients with normal blood counts at the end of treatment was 12 months. However early relapses after the treatment stop were observed more frequently in patients with initially severe neutropenia or hyperleucocytosis. The therapeutic strategy in hairy cell leukemia is discussed.

Female↗
PubMed1989

[HLA and diseases].

Explore the source record for details and available documents.

Genetic Diseases, Inborn↗
PubMed1988

The V gamma locus of the human T cell receptor gamma gene. Repertoire polymorphism of the first variable gene segment subgroup.

Southern blot analysis using a genomic probe of the human TCR-gamma chain first variable gene subgroup (V gamma I) was performed on DNA samples from both parents of 36 healthy Caucasian families. Two types of polymorphisms were found in these 72 unrelated DNA samples: three repertoire polymorphisms and two restriction fragment length polymorphisms (RFLP). In all cases, Mendelian inheritance of these polymorphisms was demonstrated. The most frequent repertoire polymorphism consists in the lack of the V gamma 4 and V gamma 5 segments. In 16% of chromosomes, the Eco RI and Taq I restriction fragments corresponding to V gamma 4 and V gamma 5 were lacking, with no additional bands. In these cases, a decrease of 10 kb was observed in the Bam HI fragment containing all V gamma I segments as compared with samples containing V gamma 4-V gamma 5 segments. To better understand this polymorphism, which takes place in a previously incompletely defined region, the central part of the V gamma I region, including the polymorphic V gamma 4-V gamma 5 segments, was cloned. This allowed us to localize precisely the V gamma 5 segment and thus complete the description of the V gamma I region. A striking homology of DNA and deduced amino acid sequences is present between V gamma 2 and V gamma 4 and between V gamma 3 and V gamma 5, much higher than that observed between V gamma 2 and V gamma 3 and between V gamma 4 and V gamma 5. The differences in nucleotide sequence occur mainly in the intron and three hypervariable regions. These results strongly suggest a gene duplication relationship between the segments V gamma 2-V gamma 3 and the segments V gamma 4-V gamma 5. The most frequent RFLP documented in this study is due to the combined absence of the Eco RI and the Taq I sites located in the noncoding region between V gamma 3 and V gamma 4. The haplotypic frequence of this RFLP is 6.9% of the general population. As the gamma/delta receptor may play an important role in immunological response, the biological relevance of the high degree of polymorphism occurring in the V gamma I region, as well as its possible association with some immune disturbances, should be further explored.

Amino Acid Sequence↗
PubMed1988

The required interaction between monocytes and peripheral blood T lymphocytes (T-PBL) upon activation via CD2 or CD3. Role of HLA class I molecules from accessory cells and the differential response of T-PBL subsets.

Previously, we have shown that paraformaldehyde-fixed monocytes are able to fully complement, in terms of [3H]dThd incorporation, a primary stimulus delivered to purified T cells by monoclonal antibodies (mAb) reacting with CD3 or CD2 molecules. Here, we show that depending on the stimulus used (CD3 mAb or different pairs of CD2 mAb) HLA class I molecules from monocytes are directly involved in complementary signals provided to T cells. This was evidenced by the following observations: (a) mAb reacting with the heavy or light chain of class I molecules, or their Fab fragments, completely blocked proliferation of peripheral blood lymphocytes (PBL) activated by CD3 mAb; (b) mAb against the heavy chain of HLA class I but not against beta 2-microglobulin partially blocked (approximately equal to 50%) PBL activation by the CD2 "GT2 + T111" mAb pair but did not block activation by CD2 "D66 + T111" mAb; (c) this pattern of inhibition was observed when anti-class I mAb were used in the soluble phase or when they were bound to monocytes subsequently fixed with paraformaldehyde and cultivated with purified autologous T cells; (d) fixed monocytes are able to restore interleukin (IL) 2 receptor expression on purified T cells stimulated by CD3 mAb or CD2 "GT2 + T111", contrary to anti-HLA class I mAb-pretreated monocytes. The inhibitory effects of anti-HLA class I mAb bound to monocytes were not found to be reversed by recombinant IL2 or recombinant IL1. We assume that HLA class I would be involved in two or more signals delivered to T cells by monocytes, the requirement in those signals depending on the initial stimulus applied to T cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Monoclonal↗
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↗