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L Amiot

Publications and source records attributed to L Amiot.

33 records · Page 2Linked to original sources
PubMed1997

CD3- CD56+ non-Hodgkin's lymphomas with an aggressive behavior related to multidrug resistance.

CD56 expression has been reported previously in some non-Hodgkin's lymphoma (NHL) characterization. They principally involve the nasopharynx, are related to Epstein-Barr virus (EBV), and may be classified as either T- or non-T-natural killer (NK) cells according to CD3/T-cell receptor (TCR) status at the genomic or protein level. The present study reports three cases of non-nasal NK-NHL with the following characteristics: an agressive clinical behavior, heterogenous morphological data evoking pleomorphic T-cell malignant lymphoma, a non-T-NK phenotype using flow cytometry, and immunochemistry. The three cases were CD56+ without membrane expression of specific T markers (CD3, CD5, and TCR). Heterogenous results were observed concerning different antigens: CD2, CD4, CD8, CD16, CD94, CD122, TiA1, perforin, and granzyme B. There was no evidence of detectable clonal TCR gene rearrangement with polymerase chain reaction. No NK activity was detected in the two tested cases, and no relation was found with EBV. Multidrug resistance investigations suggest that agressive clinical findings could be related to MDR1 gene expression as confirmed by MDR1 mRNA detection, MDR1 gene product (Pgp) expression, and a functional multidrug resistance study using rhodamine efflux by flow-cytometry.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1997

Inapparent polycythemia vera: an unrecognized diagnosis.

PURPOSE: The Polycythemia Vera Study Group (PVSG) has established useful criteria for the diagnosis of polycythemia vera. In some circumstances, an increase of plasma volume (PV) masks that of red cell mass (RCM), with hemoglobin (Hb) and hematocrit (Ht) remaining normal. This defines the concept of inapparent polycythemia. PATIENTS AND METHODS: One hundred and three patients seen in the hematology unit with the diagnosis of polycythemia vera were studied. There were 55 males and 48 females with a median age of 59 years. Ninety-five patients fulfilled the PVSG criteria. Spontaneous erythroid colonies and low serum erythropoietin level confirmed the diagnosis in the 8 other cases. Patients were classified according to Hb and Ht level. RESULTS: Group A consisted of 85 patients with increased Hb and Ht defined, respectively, by Hb > 18 g/dl, Ht > 0.52 in males and Hb > 16 g/dL, Ht>0.47 in females. Group B included 18 patients (17%) with inapparent polycythemia vera (IPV) defined by a normal Hb and Ht value at diagnosis. In this group, the reasons to perform RCM were as follows: splenomegaly associated with increased platelets and/or leucocytes counts (n = 8), portal vein thrombosis (n = 5), increased platelets or leucocytes counts without splenomegaly (n = 3), and isolated splenomegaly (n = 2). The two groups were balanced in terms of age, sex, leucocyte, serum iron, and platelet level. Hemoglobin and Ht levels were significantly different between the two groups. The difference between the PV was indeed highly significant. The mean PV increase was + 9.5% (nL < +20%) in group A versus + 36.3% in group B (P < 0.00005). Red cell mass was not different between the two groups. CONCLUSIONS: Increased Hb or Ht should constitute the sole criteria for RCM determination. In the context of portal vein thrombosis, isolated hyperleucocytosis, thrombocytosis, or splenomegaly, a RCM should be performed. The frequency of IPV remains to be specified but the diagnosis of polycythemia vera is probably underestimated.

Adult↗
PubMed1997

CpG methylation patterns in the 5' part of the nonclassical HLA-G gene in peripheral blood CD34+ cells and CD2+ lymphocytes.

A dominant goal of research focused on the nonclassical human leukocyte antigen G (HLA-G) gene is to understand the molecular mechanism involved in its limited expression. In the present report, we examined DNA methylation as a potential regulatory mechanism of HLA-G transcription in two cell types of the adult lymphomyeloid lineage: CD2+ lymphocytes express several mRNA isoforms while transcripts are undetectable in CD34+ hematopoietic cells. The methylation status of 63 CpG sites in the promoter and in the 5' CpG island was established using bisulfite-treated genomic DNA sequencing. Methylation was first analyzed by the direct sequencing of bisulfite-treated and amplified products. The general patterns of CpG methylation in the 5' part of the gene were found to be similar for CD34+ cells and CD2+ lymphocytes: the distribution of methylation was not uniform across the 63 CpG sites. In the promoter region, both CpG dinucleotides were partially or fully methylated whereas in the CpG island, several CpG sites were totally demethylated. Unexpectedly, in HLA-G positive CD2+ lymphocytes, a great number of CpG dinucleotides displayed a higher frequency of methylation relative to that found in CD34+ cells. However, the sequence analysis of cloned products revealed that the molecules have different methylation patterns which suggests that the HLA-G gene is differentially expressed in CD2+ cells. Our results suggest that methylation is not the sole mechanism that achieves the repression of HLA-G transcription in immature CD34+ cells.

Adult↗
PubMed1996

HLA-G transcription studies during the different stages of normal and malignant hematopoiesis.

Specific expression of the non classical class I HLA-G gene on trophoblasts, the only fetal tissue in contact with maternal cells which lack MHC class I antigens, may indicate a role of this gene in fetal-maternal tolerance. We recently reported HLA-G transcription in peripheral blood leukocytes. In this work, we have investigated HLA-G transcription in hematopoietic stem cells, in different hematopoietic lineages and in malignant cells by using a RT-PCR technique. PCR amplification with primers specific to the exon 2 and the 3' untranslated region has enabled to detect HLA-G transcription in B and T cell populations. No transcription was found in CD34+ cells, in thymocytes, in polynuclear cells, in monocytes and in natural killer cells. Among the malignancies analyzed, HLA-G is transcribed in 2 of 13 cases of acute leukemia characterized by a monocytic contingent, in 3 of 6 CLL and in all the cases of B-NHL (n = 6). No HLA-G transcription was detected in myeloma (n = 2). The splicing type does not seem to be linked to a lymphocyte subpopulation nor to a malignant proliferation stage. These results suggest that HLA-G is a marker of mature lymphoid cells and may play an immunological function as a peptide presenting molecule. HLA-G transcription in some cases of malignancy might indicate a contribution to the tumoral progression by blocking natural killing reaction.

Antigens, Neoplasm↗
PubMed1996

HLA-G transcription studies during the different stages of normal and malignant hematopoiesis.

Specific expression of the non classical class I HLA-G gene on trophoblasts, the only fetal tissue in contact with maternal cells which lack MHC class I antigens, may indicate a role of this gene in fetal-maternal tolerance. We recently reported HLA-G transcription in peripheral blood leukocytes. In this work, we have investigated HLA-G transcription in hematopoietic stem cells, in different hematopoietic lineages and in malignant cells by using a RT-PCR technique. PCR amplification with primers specific to the exon 2 and the 3' untranslated region has enabled to detect HLA-G transcription in B and T cell populations. No transcription was found in CD34+ cells, in thymocytes, in polynuclear cells, in monocytes and in natural killer cells. Among the malignancies analyzed, HLA-G is transcribed in 2 of 13 cases of acute leukemia characterized by a monocytic contingent, in 3 of 6 CLL and in all the cases of B-NHL (n = 6). No HLA-G transcription was detected in myeloma (n = 2). The splicing type does not seem to be linked to a lymphocyte subpopulation nor to a malignant proliferation stage. These results suggest that HLA-G is a marker of mature lymphoid cells and may play an immunological function as a peptide presenting molecule. HLA-G transcription in some cases of malignancy might indicate a contribution to the tumoral progression by blocking natural killing reaction.

HLA Antigens↗
PubMed1996

Distribution of HLA-G alternative mRNAs including soluble forms in normal lymphocytes and in lymphoid cell-derived leukemia.

The non-classical HLA-G gene is the only class I antigen expressed in trophoblasts at the maternofetal interface. In placenta, the HLA-G gene produces several alternatively spliced isoforms encoding bound-membrane proteins (G1, G2, G3 and G4) lacking, respectively, exon 7; exons 7 and 3; exons 7, 3 and 4, and exons 7 and 4. In addition, two isoforms (G1s and G2s) containing an intron 4 sequence are able to encode soluble antigens. We have recently reported that the HLA-G gene is transcriptionally active in lymphocytes and is not transcribed in CD34+ cells, polynuclear cells or monocytes. To investigate the functional significance of the different isoforms in lymphocytes, we studied their distribution in normal T and B lymphocytes and in malignant lymphoid cells by using the RT-PCR technique followed by hybridization with exon-specific probes and sequencing assays. In transcriptionally active lymphocytes, the HLA-G primary transcript is the major form and is differentially spliced in B and T lymphocytes: (i) G1s is found in several samples of T and B cells whereas G2s is only transcribed in T lymphocytes, (ii) the G4 isoform is never detected in B lymphocytes. In addition, we have shown that HLA-G is inactive in some samples of lymphocytes. Our data suggest that HLA-G transcription is regulated at the initiation level and at the subsequent splicing. These two levels of regulation may be dysregulated in some cases of T-ALL and CLL. The potential functions of the HLA-G alternative forms in lymphocytes, such as peptide binding and modulation of the immune response, are discussed.

Alternative Splicing↗
PubMed1995

Plasmacytoid CD8 lymphoma: morphologic and immunologic characterization.

This study describes a 79 year-old female suffering from fever and lymphadenopathy. A lymph node biopsy showed diffuse infiltration of medium-sized cells with plasmacytoid features. The immunologic phenotype determined by cytometric analysis and immunochemistry showed suppressor T antigen (CD2, CD3, CD7, CD8) expression. Absence of CD5 expression characterized this abnormal T cell proliferation. Gamma T cell receptor rearrangement without immunoglobulin heavy-chain gene rearrangement confirmed the T lineage of these plasmacytoid cells and their clonality. Immunological studies are necessary for identification of this T lymphoma with B microscopic findings.

Aged↗
PubMed1995

Multi-drug resistance (MDR) activity in acute leukemia determined by rhodamine 123 efflux assay.

We prospectively analyzed MDR functional activity by the Rh123 efflux assay in 84 de novo acute leukemias. Thirty of the 60 AML cases (50%) showed a positive dye efflux (in more than 10% of blast cells). In 19 cases, the dye efflux was superior to 30%. Twenty-four of the 30 efflux positive cases were CD34+ and could be studied in double staining. The mean percentage of effluxing CD34+ blast cells was 54%. There was a high correlation between CD34 expression and MDR activity (P < 10(-4)), MDR activity and PgP expression (P < 10(-6)). All the efflux negative samples were PgP negative. Nine efflux positive cases were PgP negative. Five of the 24 ALL were efflux positive. MDR activity did not correlate with FAB subtype (with the exception of AML3: 1/6 was efflux positive), age, white blood cell count or LDH level. Forty-seven AML patients were treated with conventional chemotherapy including cytarabine and an anthracycline. Thirty-one (66%) entered complete remission (CR). CR rate was statistically lower for efflux positive as compared to efflux negative patients, 46 vs 87% (P = 0.003), for PgP+ as compared to PgP- patients, 40 vs 78% (P = 0.01), for CD34+ as compared to CD34- patients, 45 vs 84% (P = 0.005). There was no correlation between P110 expression (32 AML cases studied) and FAB subtype, MDR status and clinical outcome. Two years survival was 20% for efflux positive patients as compared to 54% for efflux negative patients (P < 0.07), 15% for PgP+ vs 54% for PgP- patients (P < 0.04). The finding of efflux+/PgP- cases suggests the existence of other membrane efflux pumps. Rh123 efflux assay is straightforward in routine and could be included in MDR screening because of its potential interest in clinical outcome in AML.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1994

Improvement of hematologic recovery after high-dose intensification using peripheral blood progenitor cells (PBPC) mobilized by chemotherapy and GM-CSF.

We have tested the efficiency of GM-CSF to mobilize peripheral blood progenitor cells (PBPC) and evaluated the hematological reconstitution after GM-CSF primed-PBPC infusion following myeloablative therapy. Twenty three patients suffering from hematological malignancies were included in this study. Starting 24 hours after completion of a standard dose chemotherapy including vindesine, cyclophosphamide, adriblastine, prednisone, (VCAP), 5 micrograms/kg sub-cutaneous daily dose GM-CSF was given for a median time of 14 days followed by three consecutives cycles of leukapheresis. Fifteen of these 23 patients underwent GM-CSF primed-PBPC autotransplantation following high dosed intensification regimen. PBPC collection and hematopoietic recovery were compared with a 15 patients control group who did not receive GM-CSF. No marrow or growth factors were administered after PBPC reinfusion in the two groups. VCAP/GM-CSF mobilization induced significantly higher yields of CFU-GM (3.8 fold) than did VCAP mobilization alone, 19 x 10(4)/kg (2-73) vs 5 x 10(4)/kg (2-27), (p < 0.005). The median number of days to achieve 1.10(9)/l neutrophils, platelet count > 20.10(9)/l and > 50.10(9)/l was significantly lower in the GM-CSF group than in the control group, respectively 13 vs 19 days (p = 0.04), 15.5 vs 27 days (p < 0.02), 19 vs 51 days (p < 0.01). When compared with the control group, transfusion requirements and median of hospital stay were both significantly decreased for the patients receiving GM-CSF primed-PBPC. Our study confirms that infusion of GM-CSF primed-PBPC as a sole source of hematopoietic support improves hematopoietic reconstitution following myeloablative therapy.

Adult↗
PubMed1994

The HLA-G gene is expressed at a low mRNA level in different human cells and tissues.

Recently, HLA-G transgenic mice were shown to exhibit transgene transcription in several extraembryonic tissues. To determine whether HLA-G mRNAs are also expressed in other human tissues, we have undertaken Northern blot and RT-PCR assays using HLA-G locus-specific probe and primers. These studies demonstrate that the HLA-G gene is transcribed in a variety of cells and adult tissues obtained from different individuals (peripheral blood leukocytes, placenta, skin, spleen, thymus, prostate, testicle, ovary, small intestine, colon, heart, brain, lung, liver, and kidney), as well as in fetal tissues (heart, lung, liver, and kidney). The HLA-G mRNA level observed in most tissues is orders of magnitude lower than the level of classic class I genes in the same tissues. RT-PCR studies have demonstrated that alternative splicing of the HLA-G primary transcript is different from tissue to tissue and could be regulated in a tissue-specific fashion. Sequencing of keratinocyte transcripts has confirmed previous observations: (a) three different alternative splicing transcripts are produced (a full-length transcript, an mRNA lacking exon 3, and a transcript devoid of exon 3 and 4) and (b) HLA-G polymorphism is limited in the coding regions. In view of this wide HLA-G tissue distribution, a new hypothesis dealing with possible HLA-G function is proposed.

Alternative Splicing↗
PubMed1993

Detection of P glycoprotein activity on normal and leukemic CD34+ cells.

Rhodamine 123 is transported by the transmembrane efflux pump P glycoprotein (Pgp). We used this fluorescent dye to study multidrug resistance (MDR) activity in normal and leukemic CD34+ cells. These immature cells had a high degree of MDR activity. Among leukemic cells, CD34+ leukemias had significantly higher MDR activity as compared to CD34- leukemias. Heterogeneous results in cell subpopulations, however, indicate that prognosis should be interpreted in the light of MDR analysis.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMedDate not supplied

[Flow cytometry: application for the diagnosis and the follow-up of hematological malignancies].

Diagnosis of haematological malignancies is based on multiparametric analysis such as morphology, phenotype and genotype studies. Some entities are only defined by one of these approach. Flow-cytometry (FCM) is useful to determined the normal counterpart of the tumoral process and its differentiation status within the involved lineage. Furthermore, FCM is able to detect clonality in B or T proliferations and criteria for malignancies such as abnormal phenotype. Finally it also specifies prognosis criterias. Among the different haematological malignancies, acute lymphoblastic leukaemia (ALL) can be diagnosed using FCM, whereas acute myeloblastic leukaemia diagnosis is only confirmed by this methodology, which could moreover determine prognosis factors. A scoring system (EGIL) determine the normal counterpart of tumoral cells using a panel of different markers. Immunophenotyping is also useful in chronic lymphoproliferative disorders, such as chronic lymphocytic leukaemia (CLL) by using a similar scoring system (so-called Matutes scoring). Since FCM is able to detect simultaneously numerous cell markers it could be more accurate than immunohistochemistry for the diagnosis of follicular lymphoma, mantle cell lymphoma or hairy cell leukaemia. Finally, during treatment follow-up, minimal residual disease characterised by the detection of rare specific events, may be examined using FCM, in some situations.

Antibodies, Monoclonal↗