Biomedical subjects

F Sigaux

Publications and source records attributed to F Sigaux.

At least 73 records · Page 4Linked to original sources

PubMed1995

Expression of V beta gene segments by Sezary cells.

The T-cell receptor V beta repertoire expressed by Sezary cells was determined in a series of 16 patients whose samples have been shown to contain a majority of tumor cells. By using anti-V beta monoclonal antibodies, polymerase chain reaction analysis of expressed V beta, and, in selected cases, nucleotide sequencing, we have shown that the expressed V beta segments belong to five V beta families (V beta 5, V beta 6, V beta 8, V beta 13, and V beta 18), which contain a large fraction of the T-cell receptor V beta repertoire and do not share significant similarities in complementary determining region 4. V beta segments from these five families were also found to be strongly expressed by CD4 + CD7- peripheral blood cells obtained by fluorescence-activated cell sorting from two healthy donors. The diversity of the V beta repertoire expressed by Sezary cells appears to be similar to that expressed by circulating non-neoplastic T cells. These data do not support the hypothesis that a common superantigen is involved in the initiation of this form of cutaneous T-cell lymphoma.

Antigens, CD↗

PubMed1995

Assessment of clonal evolution at Ig/TCR loci in acute lymphoblastic leukaemia by single-strand conformation polymorphism studies and highly resolutive PCR derived methods: implication for a general strategy of minimal residual disease detection.

Junctional sequences of immunoglobulin (Ig)/T-cell receptor (TCR) gene rearrangements are used as patient-specific PCR targets for the detection of minimal residual disease (MRD) in acute lymphoblastic leukaemias (ALLs). Clonal evolution of gene rearrangements is a major pitfall of this strategy. Using high-resolution PCR-based analyses (including denaturing gel electrophoresis and single-stranded conformation polymorphism (SSCP)) we have compared Ig/TCR gene rearrangements at presentation and relapse in a series of ALLs. These methods allow an unambigous comparison of rearrangements taking into account junctional size and nucleotide sequence information and allow a precise assessment of the clonal evolution. V gamma-J gamma and V delta 1-J delta 1 rearrangements were analysed in 12 T-ALLs. VH-JH, V gamma-J gamma, V delta 2-D delta 3 and, in selected cases, DH-JH rearrangements were studied in 14 B-lineage ALLs. Clonal evolution, regarding major rearrangements, occurs for at least one of these loci in 2/12 T-ALLs and in 5/14 B-lineage ALLs. Clonal evolution is more marked for minor rearrangements than for major ones. As shown using SSCP analysis, rearrangements observed at relapse are sometimes found in minor clones at presentation which are therefore selected in vivo by a proliferative advantage. These data, as well as those from the available literature, suggest the use of at least two patient-specific probes to detect MRD in ALLs. A general strategy including selected Ig/TCR rearrangements and chromosomal abnormalities as PCR targets is proposed.

Adolescent↗

PubMed1995

Detection of clonal T-cell receptor gamma gene rearrangements with the use of the polymerase chain reaction in cutaneous lesions of mycosis fungoides and Sézary syndrome.

BACKGROUND AND DESIGN: We used the amplification of junctional V (variable)-J joining sequences of the rearranged T-cell receptor gamma (TCR gamma) genes by polymerase chain reaction for rapid and sensitive detection of a clonal T-cell population in a total of 51 skin specimens obtained from 45 patients with mycosis fungoides, five patients with Sézary syndrome, and 29 patients with chronic inflammatory dermatoses. RESULTS: A clonal TCR gamma gene rearrangement was present in all tumors (3/3, 100%) and in most infiltrated plaques (16/22, 73%) and erythrodermas (10/12, 83%). In the patch stage, a clonal subset was found in more than half of the cases (8/14, 57%), whereas no clonality was observed in the controls. We also amplified the V-J sequences of the Igh locus coding for the heavy chain of immunoglobulins, without evidence of clonal rearrangement. These data were compared with those from in situ immunophenotypic analysis. Moreover, by using the same assay with successive dilutions of standard clonal T-cell DNA, a semiquantitative study of the T-cell clone was carried out in some cases. The highest ratios of clonal DNA were observed in advanced stages. CONCLUSIONS: These data validate polymerase chain reaction V gamma-J gamma as a rapid, sensitive tool that can be used in the routine analysis of clonality in cutaneous lesions of mycosis fungoides and in the early diagnosis of mycosis fungoides and Sézary syndrome. Semiquantitative studies suggest that the malignant T-cell clone follows a selective process during the course of the progressive form of mycosis fungoides.

Clone Cells↗

PubMed1995

Lack of evidence of HTLV-I/II infection in T CD8 malignant or reactive lymphoproliferative disorders in France: a serological and/or molecular study of 169 cases.

Human T lymphotropic virus type II (HTLV-II), originally isolated in 1982 from a patient with a "T hairy cell leukemia", has not yet been proven to be the causative agent of any specific hematological disease. In order to screen for such an event, and because HTLV-II has a preferential tropism for OKT8 (CD8) T cells (both in vivo and in vitro), we searched for the presence of HTLV-II in lymphoproliferative diseases (LP) of CD8+ T cells. We report a serological and/or molecular study of 169 patients with a T CD8 LP, including 76 patients with malignant or reactive T CD8 LP (34 lymphomas, 27 large granular leukemias, three prolymphocytic leukemias, one hairy cell leukemia, 11 reactive T CD8 LP) and 93 HIV-1+ patients with a T CD8 peripheral lymphocytosis ( > 1500/mm3) from a prospective HIV cohort involving 1264 individuals. In the first series, the 40 sera available were all HTLV-I/II negative, except a 67-year-old French Guyanan man, with a cutaneous large T CD8 cell lymphoma, HTLV-I+. Furthermore, the molecular analysis of the 69 available DNA samples by PCR failed to detect any proviral HTLV-I/II sequences, except for the HTLV-I+ patient. The serological study of the 93 HIV-1+ individuals with CD8 lymphocytosis, showed that three patients were HTLV-I+, but none was HTLV-II+. Thus, in contrast to HTLV-I, whose etiological role in adult T cell leukemia is now well established, there is neither epidemiological nor molecular evidence that prototypic HTLV-II may be etiologically associated specifically with any of the CD8+ T cell LP investigated in this report.

Base Sequence↗

PubMed1994

Candidate tumor-suppressor genes MTS1 (p16INK4A) and MTS2 (p15INK4B) display frequent homozygous deletions in primary cells from T- but not from B-cell lineage acute lymphoblastic leukemias.

Using a Southern blot approach, deletions of MTS1 (multiple tumor-suppressor gene 1) and MTS2 (multiple tumor-suppressor gene 2) candidate tumor-suppressor genes have been studied in primary neoplastic cells from 55 acute lymphoblastic leukemia (ALL) patients. Homozygous MTS1 deletions were found in 20 of 24 T-ALL cases and in only 2 of 31 B-lineage cases (P < .001). The deletions involved MTS1 and MTS2 in most cases. Homozygous MTS2 deletions were observed in 16 of 24 T-ALL cases and in 1 of 31 B-lineage ALLs (P < .001), all of them displaying homozygous MTS1 deletions. In 5 cases (4 T and 1 B), deletions involved MTS1 but spared the MTS2 gene, showing that one deletion breakpoint was located between the two genes within a 25-kb region. In 1 T-ALL case, an MTS1 gene rearrangement has occurred downstream to exon 2. Possible hemizygous deletions were found in 6 cases, 4 of them of the B-cell lineage. In 7 ALL cases, cells obtained at presentation and at first relapse were studied and identical results were observed in 6 cases. In 1 B-lineage case, a germline pattern was found at presentation and a possible monoallelic MTS1/MTS2 deletion was observed at relapse. The high frequency of MTS1 and MTS2 homozygous deletions in T-ALLs supports the view that inactivation of these genes plays an important role in the pathogenesis of this type of human leukemia.

Adolescent↗

PubMed1994

Detection of minimal residual disease in acute myelomonocytic leukemia with abnormal marrow eosinophils by nested polymerase chain reaction with allele specific amplification.

Acute myelomonocytic leukemia with bone marrow eosinophilia (AML-M4Eo in the French-American-British FAB] classification) is frequently associated with pericentric inversion of chromosome 16, inv(16)(p13q22). Recently, the molecular cloning of teh breakpoints has led to the identification of the two fused genes, CBFB on 16q and MYH11 on 16p. We have analyzed 24 patients with AML-M4Eo at diagnosis and 47 patients with AML of other FAB subtypes, by a reverse-transcriptase polymerase chain reaction (RT-PCR) assay for the CBFB/MYH11 fusion mRNAs. Three types of fusion mRNAs were detected in 22 samples of AML-M4Eo (type A, n = 20; type C, n = 1; and type D, n = 1). Among these 22 positive samples, inv(16) was found in the 20 cytogenetically studied cases. No fusion transcript was detected in two patients with AML-M4Eo and in patients with other types of AML. These results confirm that CBFB/MYH11 transcripts (with a predominant type A form) are present in most cases of inv(16) AML. Moreover, detection of the hybrid transcript is closely associated with the finding of abnormal bone marrow (BM) eosinophils in AML-M4Eo as it is not found in other, FAB subtypes of AML, including AML-M4. To assess the presence of type A CBFB/MYH11 fusion transcripts in five AML-M4Eo patients in remission, we designed a sensitive assay combining nested PCR and allele-specific amplification (NPASA). Residual leukemia cells were detected in four patients who were in remission from 4 to 22 months, but not in one patient in long-term remission (5 years). The clinical relevance of persistent CBFB/MYH11 fusion transcripts in remission remains to be established by studying a large prospective series of patients. NPASA provides a useful and sensitive tool for the detection of minimal residual disease in inv(16) AML and, potentially, in other leukemias associated with translocations that result in a predominant fusion transcript.

Alleles↗

PubMed1994

Immunophenotype of adult acute lymphoblastic leukemia, clinical parameters, and outcome: an analysis of a prospective trial including 562 tested patients (LALA87). French Group on Therapy for Adult Acute Lymphoblastic Leukemia.

The aim of the multicentric trial LALA87 was to test the efficacy of different postremission therapies in adults (15 to 60 year olds) with acute lymphoblastic leukemia (ALL). An immunologic subclassification based on surface marker expression was proposed. Among the 562 tested patients, 511 were assigned either to the B lineage (361 cases, 63%) or to the T lineage (150 cases, 26%). T-ALL were significantly associated with male sex, age less than 35 years, mediastinal mass, central nervous system involvement, high white blood cell count, and low anemia. In a univariate and multivariate analysis, T-cell leukemia had a more favorable outcome than B-cell leukemia with respective median disease-free survivals (DFSs) of 28 and 14 months (P < .005). However, the type of postremission therapy modifies the value of the immunophenotype prognostic factor. In the chemotherapy arm, T-ALL patients (26 patients) had a more favorable outcome than B-ALL patients (57 patients) (P < .003). In the autologous bone marrow transplantation (ABMT) arm, the apparent better outcome of T-ALL patients (35 T/50 B) did not reach statistical significance (P = .2) and there was no difference in the allogeneic bone marrow transplantation (alloBMT) arm (37 T/71 B: P = .9). In the B-cell-lineage leukemias, subclassification by stages and myeloid antigen coexpression (10%) were not associated with different prognosis. CD10+ T-ALL (31 patients) were associated with a better DFS compared with the CD10- T-ALL (73 patients) with respective median DFS, not reached and 18.5 months (P = .04).

Adult↗

PubMed1994

Oligoclonal expansion of CD8+ CD57+ T cells with restricted T-cell receptor beta chain variability after bone marrow transplantation.

A major expansion of CD8+57+ lymphocytes expressing an alpha-beta T-cell receptor (TCR) is frequent after bone marrow transplantation (BMT). We examined the clonality of the TCR beta gene repertoire in these expanded CD8+57+ cells after allogeneic or autologous BMT. We performed a polymerase chain reaction (PCR) analysis of the V beta chain usage in CD8+57+ cells purified from nine BMT recipients with a series of oligonucleotides specific for 20 V beta gene families. PCR products from selected TCR beta gene rearrangements were sequenced. The CD8+57+ cells from eight of nine patients used a restricted set of V beta families, with a marked predominance of two to three V beta gene families per patient, whereas the control autologous CD57- subset expressed the whole 20 V beta families. A direct sequencing analysis confirmed the V beta 16 and V beta 17 clonality in six patients, showing a striking homology in the CDR3 sequences of the V beta 16 products. The CD8+57+ cells, but not the CD57- cells, displayed an oligoclonal pattern of TCR rearrangements as shown by PCR analysis of TCR gamma gene rearrangements. Such an oligoclonal expansion of CD8+57+ cells, using a restricted set of the V beta gene families, may result from a specific TCR stimulation of a limited number of T-cell clones in BMT recipients.

Amino Acid Sequence↗

PubMed1994

Multiple nuclear factors bind to novel positive and negative regulatory elements upstream of the human MHC class I gene HLA-A11.

Quantitative expression of class I genes varies widely in different tissues, during development and in some neoplastic cells. Regulatory DNA sequences controlling levels of transcription of class I genes have been characterized in the murine and swine promoters. Although some regulatory features appear to be retained in humans, most of them are not evolutionary conserved. In this study, we identify novel DNA sequences and factors which contribute to the regulation of the human HLA-A11 gene. Two activator elements (-155 to -91 and -335 to -206) and one negative element (-172 to -156), distinct from those previously described are mapped within 335 bp upstream of exon 1 of the human HLA-A11 gene. Various nuclear factors bind to these regulatory elements, some of which are cell restricted or interact with evolutionary divergent regulatory sequences of the human class I gene promoter. Two of the five DNA-binding sites characterized in this work bind at least two proteins which compete for the occupancy of their site. The identification of these new regulatory elements provides a more comprehensive basis for the understanding of physiological or pathological modulation of MHC class I transcription in humans.

Base Sequence↗

PubMed1994

The V(D)J recombination in acute lymphoid leukemias: a short review.

Antigen recognition by lymphoid cells is mediated by cell surface receptors. Specificity of this recognition is due to somatic gene rearrangements. These recombinations involve gene segments (V, J and in some cases D) which encode the amino terminal part of antigen receptor chains. Surface immunoglobulins (sIg) function as antigen receptors for B cells. Two types of T cell antigen receptors (TCR alpha beta and TCR gamma delta) have been described whose expression at the cell surface of T cells is exclusive. V(D)J rearrangements are clone specific and occur irrespective of antigens during the early stages of lymphoid differentiation. In rare instances, recombination occurs between different Ig/TCR loci or even involve genes distinct of those coding for Ig or TCR. In some cases these genes are activated by the chromosomal rearrangement and could be involved in the transformation of lymphoid cells.

Gene Rearrangement, T-Lymphocyte↗

PubMed1994

The MTCP-1/c6.1B gene encodes for a cytoplasmic 8 kD protein overexpressed in T cell leukemia bearing a t(X;14) translocation.

The t(X;14)(q28;q11.2) translocation is associated with mature T-cell proliferations. Recently this translocation has been shown to implicate the MTCP-1/c6.1B gene on chromosome Xq28, leading to aberrant or overexpressed MTCP-1 transcripts. The potential coding role of this gene was made uncertain by the lack of a long open reading frame in its major transcripts. However, a short 204 bases open reading frame is potentially coding for a 68 amino-acid protein. Here, we show that this open reading frame sequence and the deduced product are well conserved in mouse. A 8 kD protein (p8), which corresponds to the predicted molecular weight was revealed in transient transfectants and in cell lines by Western blotting, using a rabbit antiserum. This product was absent in lymphoblastoid cell lines with deletions of the MTCP-1/c6.1B locus. A dramatic overexpression of p8 was found in leukemic cells from a patient with a t(X;14). This small protein was localized in the cytoplasm by immunofluorescence. In conclusion, MTCP-1 encodes for a cytoplasmic 8 kD product. Its potential role in leukemogenesis is supported by its overexpression in leukemia with t(X;14), but its function remains unknown.

Amino Acid Sequence↗

PubMed1993

A model for tumor suppression using H-1 parvovirus.

A model system is proposed to investigate, at the molecular level, the pathways of tumor suppression. As a tool for the selection of cells with a suppressed phenotype, we used the H-1 parvovirus that preferentially kills various neoplastic cells. From the human K562 leukemia cells, we isolated a clone, KS, that is resistant to the cytopathic effect of the H-1 virus and displays a suppressed malignant phenotype. The suppressed malignancy and the cellular resistance to H-1 killing appear to depend on the activity of wild-type p53. Whereas the KS cells express wild-type p53, the protein is undetectable in the parental K562 cells. Experiments with p53 mutants suggest that wild-type p53, in its functionally intact state, contributes to the resistance against the cytopathic effect of H-1 parvovirus.

Antigens, CD↗

PubMed1993

Peripheral selection of V delta 1+ cells with restricted T cell receptor delta gene junctional repertoire in the peripheral blood of healthy donors.

To characterize the T cell receptor (TCR) repertoire expressed by the V delta 1+ gamma/delta T cell population, we have studied the V delta 1-J delta 1 junctional sequences from peripheral blood samples of healthy donors. We show that, surprisingly, this repertoire is restricted in most healthy adults, with a donor-specific and relatively stable pattern, whereas this repertoire remains unrestricted in infants, and is similar to that of thymocytes. These data contrast with the general assumption that the junctional repertoire of V delta 1+ gamma/delta T cells is extensive, and strongly suggest that peripheral recruitment of V delta 1+ cells bearing particular TCR occurs in humans during the postnatal stage.

Adult↗

PubMed1993

MTCP-1: a novel gene on the human chromosome Xq28 translocated to the T cell receptor alpha/delta locus in mature T cell proliferations.

T-cell lymphoproliferative diseases are often associated with recurrent chromosomal translocations involving T cell receptor genes (TCR) and genes that are thought to play a role in the pathogenesis of these diseases. Whereas numerous such genes have already been identified in acute T cell leukemias, no candidate gene has yet been identified to play a role in the heterogeneous group of T cell proliferations with a mature phenotype. We here report the molecular cloning of two examples of the rare but recurrent t(X;14) translocation. The first translocation was associated with a benign clonal proliferation in an ataxia telangiectasia patient and the second with a T cell prolymphocytic leukemia. Both translocations implicated the TCR alpha/delta locus and a common breakpoint region on chromosome Xq28. A previously unidentified gene, abnormally transcribed in both T cell proliferations, was characterized in the immediate proximity of the breakpoints. This Xq28 gene has no homology with known sequences, uses a complex alternative splicing pattern and demonstrates two short open reading frames. This gene, named MTCP-1 (Mature T Cell Proliferation-1) is the first candidate gene potentially involved in the leukemogenic process of mature T cell proliferations.

Alternative Splicing↗

PubMed1992

Unexpected consistent involvement of V beta gene segments in inappropriate T-cell receptor beta gene rearrangements occurring in B-lineage acute lymphoblastic leukemias.

T-cell receptor beta (TCR beta) gene rearrangements occur in a third of early B-cell acute lymphoblastic leukemias (ALLs). V, D, and J segments involved in these inappropriate rearrangements remain unknown and are of interest, both because partial D beta J beta and complete V beta D beta J beta recombinations occur at distinct stages of thymic maturation and because these rearrangements are regulated differently. We have therefore studied in detail seven cases of B-lineage ALL that show inappropriate clonal TCR beta gene rearrangements. Analysis of genomic DNA by Southern hybridization with C beta, J beta 1, V beta 8, and V beta 11 probes suggested the involvement of V beta segment in tumor cell rearrangements. A complete genomic library constructed from one case was screened with a C beta probe, and the TCR beta gene rearrangement was cloned and fully sequenced to show an out of frame V beta 2.2-J beta 2.6 recombination. TCR beta gene rearrangements occurring in other cases were further analyzed by polymerase chain reaction (PCR) using J beta and V beta primers and the resulting specific PCR products were sequenced. Evidence of clonal V beta rearrangements was obtained in all cases. These unexpected findings represent the first definitive demonstration that complete V beta(D beta)J beta rearrangements can occur in B-lineage cells and contrast with the previously reported lack of V beta(D beta)J beta rearrangement in B cells from V beta-J beta-C beta-E mu transgenic mice. In the context of increasing evidence that rearrangements are linked to transcription of unrearranged gene segments, these data prompt a search in B-lineage ALL cells for the presence of germline V beta transcripts whose deregulated expression may be linked to early transforming events.

Animals↗

PubMed1992

Interferon-alpha downregulates the abnormal intracytoplasmic free calcium concentration of tumor cells in hairy cell leukemia.

Hairy cell leukemia (HCL) is a B-cell tumor affecting the preplasma stage of B-cell differentiation. One important feature of the disease is its exquisite sensitivity to interferon-alpha (IFN-alpha) therapy. Because we showed earlier that the CD20 molecule is consistently hyperphosphorylated in hairy cells and because previous studies showed that CD20 is involved in regulating intracytoplasmic free calcium concentrations ([Ca2+]i) in normal B lymphocytes, we measured [Ca2+]i in tumor cell samples from patients with HCL and studied the effect of IFN-alpha on this parameter. Using the Ca(2+)-sensitive fluorophore fura-2, we observed that hairy cells display a slightly but consistently higher [Ca2+]i than normal 48-hour-activated B cells or other leukemic cells. Furthermore, both in vitro preincubation of cell samples with IFN-alpha and in vivo administration of this cytokine reduced the [Ca2+]i in hairy cells. This effect was observed together with a decrease in transmembrane Ca2+ influx. However, preincubation with IFN-gamma had no effect. The in vivo correlation between the diminution of CD20 phosphorylation and [Ca2+]i in tumor cell samples from patients at the beginning of IFN-alpha therapy suggests that these two parameters are connected.

Antigens, CD↗

PubMed1992

Specific polypeptide markers in chronic B cell malignancies detected by two-dimensional gel electrophoresis.

Two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) analysis of silver stained polypeptides was used to discriminate the cell protein profiles in chronic B cell malignancies. We identified 5 distinct polypeptides (H1 to H5) present in hairy cell leukemia (HCL) (14 cases) and absent in most chronic lymphocytic leukemia (CLL) and normal B lymphocytes. Two polypeptides, H2 and H5, were absolutely specific of HCL. The 2-D PAGE profiles found in 3 splenic lymphoma with villous lymphocytes (SLVL) and 2 HCL variants (HCL-V) were similar to HCL with a unique additional peptide present in 3/3 SLVL and 1/2 HCL-V. When HCL and SLVL were assessed for the CLL stage-specific 2-D PAGE patterns, HCL was related to stage A/B while SLVL was related to stage C. In conclusion, 2-D PAGE analysis of the molecular pattern of B lymphocytes provides a new means to recognize the leukemic origin of the sample and distinguish HCL from CLL and SLVL.

Adult↗

PubMed1992

Seven years of recurrent severe strongyloidiasis in an HTLV-I-infected man who developed adult T-cell leukaemia.

OBJECTIVE: Human T-cell leukaemia/lymphoma virus type I (HTLV-I) is endemic in Japan, the Caribbean basin and Africa, where it has been aetiologically linked to certain chronic myelopathies and adult T-cell leukamia (ATL). We sought to investigate whether strongyloidiasis, a parasitic disease common in these areas, might be a cofactor in the pathogenesis of ATL, as some reports have suggested. PATIENTS, PARTICIPANTS: One 35-year-old HTLV-I-seropositive French West Indian man with a 7-year history of recurrent strongyloidiasis associated with episodic hyperinfestation presenting at the Centre Hospitalier Intercommunal, Villeneuve St Georges, France. INTERVENTIONS: Treatment with various chemotherapeutic agents and symptomatic therapy for hypercalcaemia and antiviral therapy (zidovudine and interferon). RESULTS: The patient developed ATL and died shortly after, despite chemotherapy. Immunological and virological studies performed during the last 15 months of his life showed an increase of the percentage of peripheral ATL cells, and progression from a polyclonal to a monoclonal integration of HTLV-I proviral DNA in the peripheral blood mononuclear and lymph-node cells. CONCLUSIONS: Recurrent strongyloidiasis appears to have been a possible cofactor associated with progression from healthy carrier state to ATL in our patient.

Adult↗