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O Azogui

Publications and source records attributed to O Azogui.

At least 19 recordsLinked to original sources
PubMed2000

Different initiation of pre-TCR and gammadeltaTCR signalling.

Lineage choice is of great interest in developmental biology. In the immune system, the alphabeta and gammadelta lineages of T lymphocytes diverge during the course of the beta-, gamma- and delta-chain rearrangement of T-cell receptor (TCR) genes that takes place within the same precursor cell and which results in the formation of the gammadeltaTCR or pre-TCR proteins. The pre-TCR consists of the TCRbeta chain covalently linked to the pre-TCRalpha protein, which is present in immature but not in mature T cells which instead express the TCRalpha chain. Animals deficient in pre-TCRalpha have few alphabeta lineage cells but an increased number of gammadelta T cells. These gammadelta T cells exhibit more extensive TCRbeta rearrangement than gammadelta T cells from wild-type mice. These observations are consistent with the idea that different signals emanating from the gammadeltaTCR and pre-TCR instruct lineage commitment. Here we show, by using confocal microscopy and biochemistry to analyse the initiation of signalling, that the pre-TCR but not the gammadeltaTCR colocalizes with the p56lck Src kinase into glycolipid-enriched membrane domains (rafts) apparently without any need for ligation. This results in the phosphorylation of CD3epsilon and Zap-70 signal transducing molecules. The results indicate clear differences between pre-TCR and gammadeltaTCR signalling.

Animals↗
PubMed1999

Pleiotropic changes controlled by the pre-T-cell receptor.

The construction of various gene-deficient mice has facilitated the understanding of the role of various receptors and signaling pathways that control the generation of alphabeta lineage cells. A predominant role is occupied by the pre-TCR, which not only generates large numbers of alphabeta lineage cells but also controls TCRbeta allelic exclusion as well as commitment to the gammadelta lineage versus the alphabeta lineage.

Alleles↗
PubMed1998

On the role of the pre-T cell receptor in alphabeta versus gammadelta T lineage commitment.

The role of the pre-T cell receptor (TCR) in lineage commitment to the gammadelta versus alphabeta lineage of T cells was addressed by analyzing TCRbeta chain rearrangements in gammadelta T cells from wild-type and pre-TCR-deficient mice by single cell polymerase chain reaction. Results show that the pre-TCR selects against gammadelta T cells containing rearranged Vbeta genes and that gammadelta T cell precursors but not gammadelta T cells express the pre-TCRalpha protein. Furthermore, pre-TCR-induced proliferation could not be detected in gammadelta T cells. We propose that the pre-TCR commits developing T cells to the alphabeta lineage by an instructive mechanism that has largely replaced an evolutionary more ancient stochastic mechanism of lineage commitment.

Animals↗
PubMed1998

Crucial function of the pre-T-cell receptor (TCR) in TCR beta selection, TCR beta allelic exclusion and alpha beta versus gamma delta lineage commitment.

The analysis of T-cell receptor (TCR) beta selection, TCR beta allelic exclusion and TCR beta rearrangement in gamma delta T cells from normal and pre-TCR-deficient mice has shown that the pre-TCR has a crucial role in T-lymphocyte development: The pre-TCR is by far the most effective receptor that generates large numbers of CD4+8+ T cells with productive TCR beta rearrangements. In the absence of the pre-TCR, TCR beta rearrangement proceeds in developing cells irrespective of whether they already contain a productive TCR beta gene. The pre-TCR directs developing T cells to the alpha beta lineage because gamma delta T cells from pT alpha-/- mice proceed much further in TCR beta rearrangement than gamma delta T cells from wild-type mice. It is argued that the pre-TCR commits developing T cells to the alpha beta lineage by an instructive mechanism, which has largely replaced an evolutionarily more ancient mechanism that involves stochastic alpha beta lineage commitment.

Alleles↗
PubMed1997

Essential role of the pre-T cell receptor in allelic exclusion of the T cell receptor beta locus.

Following the recent realization that TCR beta transgenes can severely inhibit the rearrangement of endogenous Vbeta gene segments in the absence of pre-TCR alpha (pT alpha) chains, we tested whether the pre-TCR has an essential role in TCR beta allelic exclusion under more physiological conditions by analyzing TCR rearrangement in immature thymocytes by single-cell PCR. Our results in pT alpha+ mice are consistent with an ordered model of TCR beta rearrangement beginning on one allele and continuing on the other only when the first attempt is unsuccessful. By contrast, a higher proportion of thymocytes from pT alpha-/- mice exhibited two productive TCR beta alleles. Thus, the pre-TCR-independent suppression of rearrangement by TCR beta transgenes represents a transgene artifact, whereas under physiological conditions the pre-TCR is essential for allelic exclusion.

Alleles↗
PubMed1993

A novel disulfide-linked heterodimer on pre-T cells consists of the T cell receptor beta chain and a 33 kd glycoprotein.

We describe a novel signal-transducing protein complex, which consists of the T cell receptor (TCR) beta chain that is disulfide linked to a 33 kd glycoprotein and noncovalently associated with proteins of the CD3 complex on the surface of the pre-T cell line SCB.29. This 33 kd glycoprotein, provisionally designated gp33, represents neither of the known TCR chains and has escaped previous detection because it labels poorly by surface iodination. This glycoprotein is absent from the surface of mature T cell lines. A TCR beta complex with identical molecular masses before and after reduction can be immunoprecipitated from surface-iodinated large thymocytes of TCR alpha-deficient mice. The novel gp33-TCR beta complex may be entirely or partly responsible for control of early T cell development exerted by the TCR beta protein.

Animals↗
PubMed1993

Alternatively spliced T cell receptor transcripts expressed in human T lymphocytes.

We used the anchored-polymerase chain reaction (A-PCR) procedure to study human TCR transcripts derived from a variety of polyclonal T cell populations. In this series of experiments, 31 'unusual' cDNAs, which do not include exclusively V-J-C, J-C or 5'C genomic sequences, were identified. Ten of these were found to represent distinct types of alternatively spliced TCR alpha transcripts whose structure is derived from unusual splicing of one, two or even three intervening intronic sequences. The splicing events led to either conservation of a novel exon in the mRNA structure (designated aE1 alpha-aE5 alpha) between the V-J and C segments or to deletion of the 3' V region-J segment. In three cases, the alternatively spliced exons (aE1 alpha-aE3 alpha) interrupt the open translational reading frame of the corresponding V-J alpha segment. Nineteen and two cDNA represent sterile C beta or C delta transcripts, respectively. Their structures are derived from the conservation of a non-translatable exon, aE1 beta or aE1 delta, which is precisely spliced at the 5' end of the corresponding C exon sequences. Interestingly, the 3' region of the aE1 beta sequence is homologous to the murine C beta 0 exon. Together, these results led to the characterization of nine novel exons in the TCR alpha, beta and delta loci.

Alternative Splicing↗
PubMed1993

The use of anchored polymerase chain reaction for the study of large numbers of human T-cell receptor transcripts.

Anchored-PCR (A-PCR) is an approach designed to amplify and clone sequences with unknown 5' or 3' extremities. A-PCR is therefore appropriate for studying variable region of T-cell receptors (TCRs) expressed in polyclonal T-cell populations since it does not prejudge which variable gene segments are actually being used. We report here some critical modifications in the initial procedure to make it easy to clone and sequence large series of TCR transcripts. They have been introduced to improve both the yield and specificity of TCR amplified products and include re-amplification, size selections of the material combined with the successive use of nested TCR constant region specific primers. This procedure has been successfully applied to the study of the repertoire of both TCR alpha/beta+ and gamma/delta+ human T-cells. The efficiency of the present A-PCR protocol will help to precisely analyze TCR usage in normal and pathological situations.

Base Sequence↗
PubMed1993

Molecular analysis of T-cell receptor transcripts in a human T-cell leukemia bearing a t(1;14) and an inv(7); cell surface expression of a TCR-beta chain in the absence of alpha chain.

The polymerase chain reaction (PCR) was used to amplify cDNA in order to characterize normal and hybrid T-cell receptor (TCR) gene rearrangements derived from a T-cell acute lymphoblastic leukemia (T-ALL) bearing a chromosome 7 inversion. The nucleotide sequence analysis of the amplified product showed the presence of an out-of-frame V beta/J gamma/C gamma transcript and an in-frame V gamma/J gamma/C beta transcript which result from an interlocus recombination between the TCR-beta and gamma loci and the transcription of the reciprocal hybrid TCR gene. The sequence analysis of the reciprocal DNA segment directly involved in the breakpoint of the inversion showed a recombination between a J gamma-sequence heptamer signal and a coding J beta gene segment. The exonuclease nibbling of each DNA extremity and the non-templated nucleotide insertion observed at both coding and reciprocal joints demonstrate that the inversion is mediated by the lymphocyte recombinase complex. During T-cell differentiation, TCR-beta genes are rearranged prior to TCR-alpha genes. In the present case of T-ALL, we have shown that TCR-delta genes are rearranged at both loci, excluding productive rearrangements of TCR-alpha genes. The molecular analysis of the normal TCR genes derived from the leukemic cells revealed the presence of productively rearranged TCR-beta, gamma, and delta genes. Cell surface staining of these cells showed the presence of CD3 molecules and of a TCR-beta chain corresponding to the normal beta allele expressed in a disulfide-linked complex with a protein which is not TCR-alpha, gamma, or delta. This could represent the cell surface expression of the hybrid TCR-V gamma/C beta protein or the expression of a TCR-beta homodimer.

Adult↗
PubMed1992

A third tal-1 promoter is specifically used in human T cell leukemias.

A common feature of T cell acute lymphoblastic leukemias (T-ALLs) is the presence of structural alteration of the 5' part of the tal-1 locus, localized on chromosomal band 1p32. These alterations consist of either a t(1;14)(p32;q11) chromosomal translocation (3% of T-ALLs) or tald submicroscopic deletion (12-25% additional T-ALLs). We have characterized a case of T-ALL with t(1;14)(p32;q11) in which, unlike the majority of t(1;14), the recombination with the T cell receptor delta elements affected the 3' side of the tal-1 locus. In this case, tal-1 transcription is initiated from a promoter located within the fourth exon similarly to the DU 528 cell line. In a T-ALL bearing a t(1;14) affecting the 5' part of tal-1, two types of tal-1 transcripts were observed, namely those probably initiated from the D delta region juxtaposed to tal-1 by the translocation, and those from the exon 4 promoter. It is interesting that this exon 4 promotion was also found in leukemic T cell lines and T-ALL samples without apparent tal-1 genomic alteration. In contrast, no transcript initiated from the exon 4 promoter was found in T-ALL with tald1 or tald2 deletion. In these cells, tal-1 is expressed via SIL-tal-1 fused transcripts. Finally, this exon 4 initiation was detected neither in normal bone marrow, nor in malignant cells from the erythroid/megakaryocytic lineages. Taken as a whole, these data suggest that the exon 4 promoter is specifically active in T cell lineage.

Base Sequence↗
PubMed1991

Tumor-infiltrating CD3- NK cells are more effective than CD3+ T cells in killing autologous melanoma cells.

We have studied the phenotype and functional activity of tumor-infiltrating lymphocytes (TIL) derived from eight human melanomas cultured for up to 60 d in the presence of recombinant IL-2. In the early period of the cultures, TIL were predominantly T cells of CD8+ phenotype and contained 10-30% of CD3- cells. Four of the five early TIL cultures tested in a cytotoxicity assay displayed a degree of MHC-unrestricted lysis on a series of autologous and allogenic melanoma cell lines as well as the K562 natural killer-sensitive target. With longer periods of time in culture, all TIL lines showed a decrease in lytic activity that was associated with the loss of CD3- cells. Thus, most of the killing of short-term TIL cultures appeared to be mediated by CD3- natural killer cells, whereas CD3+ T cells were found to be weak anti-tumor effectors. Even though the CD3+ T cells were not cytotoxic on K562 targets, their lytic activity (even weak) against melanoma cells appeared to be non-MHC restricted, and was blocked by anti-CD3 antibodies. In addition, cytotoxicity of the CD3+ TIL cultures was compared to that of a CD3-/NKH1+ cell line purified from peripheral blood. It was found that natural killer cells were much more potent than CD3+ TIL on the melanoma cell lines tested.

Antibodies, Monoclonal↗
PubMed1989

[Adherence of monocytes to the aortic endothelium. Effect of the intraluminal pressure].

It is now generally accepted that most of the foam cells formed in the early fatty streak arise from circulating monocyte-macrophages. The effect of transmural pressure on mononuclear cells adherence to the vascular endothelium has been studied in excised rabbit thoracic aorta. Mononuclear cells were obtained from blood by centrifugation through lymphocyte separation medium (Ficoll-Paque, specific gravity 1.077). The mononuclear cell layer was collected from the interface and washed twice in RPMI containing 10 p. 100 fetal calf serum to remove contaminating platelets. The mononuclear cells were radiolabeled by incubation for 60 min in 0.1 mCi/ml of 51-chromium. After incubation, the cells were washed twice to remove free chromium, and resuspended in 5 ml RPMI containing 10 p. 100 fetal calf serum, at a concentration of 2 x 10(6) cells/ml. After ligature of intercostal arteries, 2 segments from the descending thoracic aorta were excised at in vivo length and under physiological pressure in order to preserve endothelial integrity. Arterial segments were incubated in oxygenated Krebs solution, at 39 degrees C and the intraluminal solution was changed to the solution containing the labeled mononuclear cells. The pressure was established at 70 mmHg in one segment and at 160 mmHg in the other. After 2 h incubation, the vessels were fixed under pressure. Each arterial segment was opened longitudinally and cut into 4 segments, which were laid on a microscopic slide and frozen at -20 degrees C. The surface area of each segment was measured and sections were cut en face at 20 micron intervals from the luminal surface to the adventitia.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Bone marrow transplantation for chronic granulocytic leukemia.

Thirty-seven patients with chronic granulocytic leukemia have been treated with supralethal chemoradiotherapy followed by transplantation of bone marrow from HLA-identical donors. All patients showed engraftment, and the Philadelphia chromosome (PH1) disappeared in each case. Four patients had syngeneic grafts before blast crisis and are still alive; 2 are in remission not maintained by therapy, and 2 others are receiving chemotherapy after having relapsed in the chronic phase. Thirty-three patients had allogeneic grafts; only 2 received the grafts during blast crisis, and neither is a long-term survivor. Of the 13 patients who had grafts in the accelerated phase, 6 died of complications related to the transplantation, and 1 died after a myeloblastic relapse. Thus 6 patients are in unmaintained remission with a median follow-up of 13 months. Eighteen patients received grafts in the chronic phase. All 10 survivors are in unmaintained remission with a median follow-up of 14 months; in this group, no patient has relapsed. The granulocytic hyperplasia of the chronic phase can be more effectively ablated than established blastic leukemia. The mortality rate of transplant-related complications must be weighted against the typical rate of progression of chronic granulocytic leukemia. Although a longer follow-up period is needed for full evaluation, bone marrow transplantation may now be offered to patients in the chronic phase in an attempt to achieve long-term survival or cure of more than one-half of these patients.

Adolescent↗
PubMed1985

Clinical significance of cytomegalovirus viremia in bone marrow transplantation.

Cytomegalovirus (CMV) viremia was systematically studied in 56 patients having undergone bone marrow transplantation for leukemia or aplastic anemia. Of the patients who survived at least three months, 57% had CMV viremia with a frequency peak between the 7th and the 9th weeks. We describe possible clinical signs associated with viremia, particularly late peripheral and/or central thrombocytopenia. The occurrence of viremia was studied according to the specific preexisting immune status of recipients and donors; granulocyte transfusions and graft-versus-host disease. The relationship between these parameters and viremia provides a basis for the analysis of prophylactic treatments of CMV infection.

Adolescent↗
PubMed1983

Inhibiton of IL 2 production after human allogeneic bone marrow transplantation.

Bone marrow transplantation (BMT) is currently used to treat patients with severe aplastic anemia or leukemia. Despite the use of an HLA identical sibling donor, however, the survival after BMT is reduced by the occurrence of two major immunologic complications: graft-vs-host disease and a long-lasting immune deficiency responsible for late infections. This immune deficiency could be explained by an imbalance of lymphocyte subpopulations reconstituted after transplant. The aim of the present work was to study the helper function by measuring the production of interleukin 2 (IL 2). This lymphokine is responsible for the amplification of the effector phase of immunity. A consecutive series of 34 patients was tested for IL 2 production after BMT. This production was absent or low in 32 of 34 patients for at least 2 yr after BMT. The mechanism of this low IL 2 production was investigated. Irradiation of patients' lymphocytes in vitro with low dose gamma-rays partially restored the IL 2 production after 6 mo of evolution. The IL 2 production was not restored or was slightly affected by irradiation early after BMT. These results suggest that the lack of immune reconstitution after BMT may be caused by the lack of IL 2-producing cells and/or the increased activity of suppressor cells of the helper function. This suppression is radiosensitive.

Bone Marrow Transplantation↗