Biomedical subjects

F Birg

Publications and source records attributed to F Birg.

At least 55 records · Page 3Linked to original sources

PubMed1992

Expression of the FMS/KIT-like gene FLT3 in human acute leukemias of the myeloid and lymphoid lineages.

FLT3, a receptor belonging to the FMS/KIT family and localized to 13q12, could play a role in the biology of early hematopoietic progenitor cells. Because FMS and KIT are expressed in both normal progenitors and myeloid leukemias, we looked for FLT3 expression in fresh human leukemic cells using Northern blot analysis. High levels of FLT3 expression were detected in 92% of the cases of acute myeloid leukemia (AML) tested, ranging from the M1 to the M5 stages of differentiation assessed in the French-American-British classification. Immature (MO) AML cells, biphenotypic leukemias, and AML with megakaryocytic differentiation (M7 subtype) also expressed the FLT3 transcript. FLT3 was also expressed at high levels in acute lymphoid leukemias of T and B origins. Finally, it was not expressed in chronic myeloid leukemias in chronic phase, whereas it was expressed in most blast crisis samples. This pattern of expression of FLT3 contrasts with the expression of FMS and KIT restricted to myeloid leukemias, and suggests that the FLT3 product could play a role in the expansion of the leukemic blasts of both the myeloid and lymphoid lineages.

B-Lymphocytes↗

PubMed1992

Prolonged IL-2 receptor alpha/CD25 expression after T cell activation via the adhesion molecules CD2 and CD28. Demonstration of combined transcriptional and post-transcriptional regulation.

The T cell adhesion molecule CD28 provides a costimulatory signal in combination with CD2 and CD3 mAb. CD28 regulates the expression of cytokines by T cells, not only IL-2, but also IL-1 alpha and CSF-1, usually synthesized by accessory cells. We have investigated the mechanisms through which CD28 modulates the expression of the IL-2R alpha chain. Whereas activation through CD2 or CD28 alone induced no or only low IL-2R alpha chain expression, activation through CD2 plus CD28 led to both a high and prolonged (greater than 14 days) cell surface and mRNA expression. In contrast, immobilized CD3 mAb-dependent activation induced a transient expression of the IL-2R alpha chain, which was neither further increased nor prolonged by CD28 costimulation. Upon CD2 plus CD28 stimulation, the half-lives of the two IL-2R alpha transcripts increased progressively between days 1 and 4, in contrast to each pathway alone. Whereas each activation pathway alone induced either no (CD2) or low (CD28) levels of IL-2R alpha gene transcription, the CD2 plus CD28 stimulation was associated with its increased transcription, which persisted at similar rates between 5 and 96 h post stimulation. The in vitro costimulation via the CD2 and CD28 molecules thus regulates the expression of the IL-2R alpha gene both at the transcriptional and post transcriptional levels. Our results therefore demonstrate a new immunoregulatory function of the CD28 molecule on IL-2R alpha expression, which, through its increased transcription rate and stabilization, could, together with high levels of cytokines secretion, be responsible for the prolonged T cell proliferation.

Antigens, CD↗

PubMed1992

Contributions of the CD2 and CD28 T lymphocyte activation pathways to the regulation of the expression of the colony-stimulating factor (CSF-1) gene.

The T cell adhesion molecule CD28 provides a costimulatory signal, in combination with either CD2 or CD3 mAb. CD28 appears to regulate the expression, by T cells, of cytokines normally produced by accessory cells, namely IL-1 alpha, TNF-alpha, and CSF-1. The CSF-1 gene is expressed as a 4.0-kb transcript by human T cells activated with mAb directed against CD2 and CD28, alone or in combination. A kinetic analysis of its expression showed low steady-state levels of the transcript after CD2 stimulation, and a transient rise after CD28 stimulation. In contrast, a mean fivefold increase in the levels of the transcript was detected in CD2 plus CD28-stimulated cells. The potential mechanisms regulating this increase were investigated. The half-life of the CSF-1 transcript was identical in cells activated with either CD28 or CD2 plus CD28. Transcription of the CSF-1 gene appeared to undergo attenuation in resting cells as well as in cells activated via a single pathway; this attenuation was relieved in part by the combined CD2 plus CD28 stimulation. Thus in vitro costimulation via the CD2 and CD28 molecules regulates the expression of the CSF-1 gene mainly at the transcriptional level.

Antigens, CD↗

PubMed1992

In situ expression of the IL-1-alpha and TNF-alpha genes by Reed-Sternberg cells in Hodgkin's disease.

The histopathologic pattern of tissues involved by Hodgkin's disease (HD) suggests excessive activation of environmental cells by cytokines released by Hodgkin-Reed-Sternberg (HRS) cells, which are considered as the neoplastic component of HD lesions. This hypothesis has been supported by many studies performed in vitro using HD cell lines. In this study, we have tried to demonstrate the cytokine-producing cells in an environment as close as possible to the in vivo conditions, using in situ hybridization onto frozen sections of HD samples. [35S]-labelled single-stranded RNA probes were prepared by transcribing human cDNA fragments of the TNF-alpha and IL-1 alpha genes subcloned into appropriate vectors. A total of 19 specimens of HD lesions, including 7 cases of nodular sclerosing (NS) type and 12 cases of mixed cellularity (MC), were tested with both types of probes. Clinical stages included stage I (6 cases), stage II (4 cases), stage III (6 cases) and stage IV (3 cases). TNF-alpha and/or IL-1 alpha expression was observed in 12 among 19 HD cases. However, neither the histological type nor the clinical status of the patients was correlated with the profile of cytokine secretion. Most of the cytokine-producing cells could be identified as HRS cells due to their morphological appearance. In 3 cases, simultaneous analysis by immunohistochemistry and in situ hybridization showed that IL-1 alpha/TNF-alpha mRNA-producing cells simultaneously expressed the CD30 antigen, thereby confirming the HRS nature of these cells.

Antigens, CD↗

PubMed1992

Expression of the ETS2 and transferrin receptor genes in Philadelphia-positive chronic myeloid leukemia patients with a reciprocal t(3;21).

The translocation t(3;21)(q26;q22) is a rare recurring clonal abnormality, either preceding or associated with blast crisis in Philadelphia chromosome-positive chronic myeloid leukemia (CML) patients. We previously localized the chromosomal breakpoints at 3q26.2 and 21q22.2, using high resolution chromosomal analysis. Two genes of interest are localized near the breakpoints, the transferrin receptor gene and the ETS2 proto-oncogene. Their chromosomal localizations, determined by in situ hybridization on normal metaphase cells, were 3q29 and 21q22.3, respectively. They underwent a reciprocal translocation in patients with t(3;21). Their structures were not altered by the translocation, and both were expressed to varying levels in t(3;21) patients. Southern blotting investigations showed that the structure of other single-copy genes, including FIM3, localized near the breakpoints, were not affected by the translocation. An analysis of ETS2 expression performed on CML patients without t(3;21) showed the presence of the transcript in 100% of the blast crises, but only in 20% of the chronic-phase patients. Thus ETS2 expression may either be linked to or play a role in CML progression.

Blast Crisis↗

PubMed1991

IL-1 alpha is produced by T lymphocytes activated via the CD2 plus CD28 pathways.

In addition to activation via the TCR complex, resting purified T cells can be activated to proliferate by mAb directed against the two surface molecules, CD2 and CD28. We demonstrate here that only the CD2 plus CD28 combined activation induces the expression and secretion of IL-1 alpha, a cytokine classically considered as a monokine. In contrast, neither IL-1 beta nor IL-6 were produced. A second monokine, TNF-alpha was transiently expressed by T cells activated with either CD2 or CD28 mAb, but was expressed to higher levels and with a prolonged kinetics in cells activated by the CD2 plus CD28 combination. The prolonged expression of the IL-1 alpha gene could account, at least in part, for the monocyte-independent and long lasting T cell proliferation induced by the CD2 plus CD28 co-stimulation. Secretion of monokines, such as IL-1 alpha, by activated T cells, could play a regulatory role in immune responses, as well as contribute to autoimmune processes.

Antigens, CD↗

PubMed1991

Coexpression of the genes for interleukin 6 and its receptor without apparent involvement in the proliferation of acute myeloid leukemia cells.

Leukemic cells isolated from patients with either acute myeloid leukemia (AML) or acute lymphoid leukemia (ALL) were screened for their capacity to express the interleukin 6 (IL-6) and IL-6 receptor genes, both at the RNA and protein levels. Variable levels (10 to greater than 600 U/ml) of an IL-6 activity, inhibited by neutralizing anti-IL-6 antibodies, were detected in AML cell supernatants using the B9 cell bioassay. High levels (greater than 100 U/ml) were observed in differentiated (M4 and M5 stages) AML, as well as in less mature (M1 and M2 stages) AML. Detection of the IL-6 transcript correlated with the biological activity. In addition, both IL-6 activity and IL-6 mRNA were detected in "fresh" leukemic cells, indicating that the glycoprotein was actually synthesized in vivo. In contrast, the IL-6 gene was less frequently expressed in ALL. The IL-6 receptor gene was transcribed in both AML and ALL; binding experiments showed that the protein was present at the cell surface. The spontaneous in vitro proliferation of leukemic cells coexpressing the transcripts for IL-6 and its receptor was not significantly inhibited by a neutralizing anti-IL-6 antibody, suggesting that IL-6 is not primarily implicated in the proliferation of the leukemic clone via an autocrine loop. Synthesis of IL-6 could, however, confer on leukemic cells a selective growth advantage through activation of the cytokine cascade.

Antigens, CD↗

PubMed1990

Inhibition of simian virus 40 DNA replication in CV-1 cells by an oligodeoxynucleotide covalently linked to an intercalating agent.

An octathymidylate covalently linked via its 3'-end to an acridine derivative inhibited the cytopathic effect of Simian Virus SV40 on CV-1 cells in culture. Control experiments revealed that this effect was virus-specific and did not arise as a result of oligonucleotide degradation by nucleases. A photoactive probe was covalently attached to the 5'-end of the oligonucleotide-acridine conjugate. Upon UV-irradiation, photocrosslinking was shown to occur at the A. T-rich region within the viral origin of replication. A local triple helix can form at moderate salt concentrations with two octathymidylate-acridine conjugates bound to the octaadenylate sequence. Alternatively the octathymidylate-acridine conjugate can bind to the major groove of duplex DNA forming a local triple helix. Different mechanisms are discussed to explain the inhibition of viral DNA replication.

Acridines↗

PubMed1990

Activated but not resting T cells or thymocytes express colony-stimulating factor 1 mRNA without co-expressing c-fms mRNA.

Following the observation that, besides acute myeloid leukemia cells, acute lymphoid leukemia cells of either B or T phenotype could express the transcript for the colony-stimulating factor 1 (CSF-1), a growth factor known to be restricted to the monocytic-macrophage lineage, various sources of resting and/or activated T cells and thymocytes were screened for expression of this hemopoietic growth factor. We report here that the CSF-1 transcript was rapidly (7 h) induced in T cells by a variety of stimuli, but was not detectable in either resting T cells or thymocytes. In addition, secretion of CSF-1 was detectable in the supernatants of activated T cells by 72 h, with a peak around 92-120 h. In contrast to activated monocytes, the transcript of the c-fms proto-oncogene, the product of which is the receptor for CSF-1, was not detectable in either resting or activated T cells. This observation could be relevant to the intimate relationships between T cells and antigen-presenting cells during immune responses.

Antigens, Differentiation, T-Lymphocyte↗

PubMed1990

c-fms expression in acute leukemias with complex phenotypes.

The c-fms proto-oncogene product, which is the receptor for the macrophage colony-stimulating factor CSF-1, is always found expressed in acute myeloid leukemia cells, irrespective of their stage of differentiation according to the FAB classification (Dubreuil P, Torrès H, Courcoul M, Birg F, Mannoni P. Blood 1988;72:1081-1085). We have extended this study and looked for c-fms expression in poorly differentiated myeloid leukemias, in a series of acute leukemias of either T or B origin and in biphenotypic leukemias. We now report that expression of c-fms is still related to the myeloid origin of the leukemic proliferation, but that it can also be found in some acute leukemias presenting clonal rearrangements of the T cell receptor gene. Thus expression of the c-fms/CSF-1 receptor may not be exclusively a marker for myeloid proliferations.

Acute Disease↗

PubMed1989

Study of a family with a fragile site of the X chromosome at Xq27-28 without mental retardation.

The fragile site Xq27-28 was observed in several individuals of a large family. It is expressed at a high frequency among the carrier females, even as adults, and in one clinically normal male. None of the members of this family is affected with the mental retardation normally linked to this fragile site. Cytogenetic and flanking DNA marker polymorphism studies suggest a possible dissociation between the fragile site and clinical expression of the disease.

Adult↗

PubMed1989

"Minisatellite" DNA probes detect engraftment and/or chimerism in recipients of HLA-matched bone marrow transplants.

A study was carried out to determine whether the minisatellite DNA probes described by Jeffreys and coworkers could be used routinely to analyze engraftment, hematopoietic chimerism, and relapse in recipients of bone marrow transplants. The probes were informative for all of the recipient/donor pairs analyzed. Their limit of sensitivity was determined in reconstruction experiments and was found to vary from 2%, in the best cases, to 10%. We were able to confirm that engraftment and hematopoietic chimerism can, indeed, be sought routinely using this simple molecular approach. Only one set of probes is required for all patients and, unlike cytogenetic analysis, this analysis can be used whether or not blood or marrow cells are dividing.

Bone Marrow Transplantation↗

PubMed1988

Dissociation between mental retardation and fragile site expression in a family with fragile X-linked mental retardation.

We report an extended family in which two brothers with a fragile X chromosome are mentally retarded while a third brother with the fragile site is both phenotypically and mentally normal. The study of six probes detecting restriction fragment length polymorphisms on either sides of the fragile site Xq27 confirmed that the fragile X regions inherited by these three brothers were identical from DXS102 to the telomere. These data highlight the heterogeneity of the fragile X syndrome, which is discussed in the framework of the different hypotheses previously proposed.

Child↗

PubMed1988

c-fms expression is a molecular marker of human acute myeloid leukemias.

The c-fms protooncogene product was identified as the CSF-1 or M-CSF receptor, a polypeptide growth factor that plays a major role in myelomonocytic differentiation. This led us to look for expression of c-fms in fresh acute myeloid leukemia (AML) cells, using Northern blot analysis. c-fms expression was found in the leukemic cells of 28 AML patients, regardless of their stage of differentiation, which was assessed in the French-American-British (FAB) classification. However, the level of c-fms expression was especially high in AML of the M5 stage. High levels of expression were not accompanied by either amplification or rearrangements of the c-fms gene in AML cell DNAs. In contrast, c-fms expression was not found in acute lymphoid leukemias, whether of T or B origin. Thus, c-fms expression appears as a specific molecular marker of leukemogenesis in the myeloid lineage.

Biomarkers, Tumor↗

PubMed1987

Localization of the mcf.2 transforming sequence to the X chromosome.

A transforming sequence was identified using co-transfection of DNA from the human mammary carcinoma cell line MCF-7 and of a G418 resistance gene into NIH 3T3 cells, followed by tumor formation in athymic mice. This sequence, named mcf.2, was molecularly cloned. A transforming activity resides in a cosmid clone of 42 kb. mcf.2 did not cross-hybridize with the known oncogenes tested. In situ hybridization localized it on the X chromosome, probably at q27. This localization was confirmed by hybridization to a panel of human--rodent cell line DNAs.

Animals↗

PubMed1986

Polyomavirus-transformed FR 3T3 rat cells are able to form metastases in syngeneic rats.

A series of polyomavirus-transformed FR 3T3 rat cell lines were tested for their tumorigenic and metastatic properties after subcutaneous inoculation of syngeneic Fisher rats. All of them grew into tumors, which appeared with variable latency periods; the TD50 varied from cell line to cell line. Eight of the 18 transformants that were inoculated gave rise to metastases, always localized in the lung. The capacity to form metastases, though at a low frequency, was also conferred on FR 3T3 cells upon transformation with a recombinant plasmid encoding only the middle-T protein. Fibroblast-like cells were predominantly observed upon histological examination of the metastases. Culture cell lines were derived from independent tumors and metastases induced by two transformants with low and high metastatic potentials, respectively. Metastasis-derived cell lines exhibited metastatic potentials similar to those of the respective original transformants. All the tumor- and metastasis-derived cell lines synthesized the same early viral polypeptides as the respective original transformants; in contrast, the viral DNA integrations evolved during tumor and metastasis formation.

Animals↗

PubMed1985

Permanent expression of p53 in FR 3T3 rat cells but cell cycle-dependent association with large-T antigen in simian virus 40 transformants.

The p53 oncogene is thought to play a role in the proliferation of normal and transformed cells and its expression was postulated to be cell cycle dependent. Using flow cytofluorimetry sorting of populations of exponentially growing cells, coupled to a radioimmune assay, we have investigated the accumulation of p53 along the cell cycle in normal FR 3T3 rat cells as well as in two types of SV40-transformed derivatives, one of which only expresses the large-T protein during the G2 phase of the cell cycle. p53 was accumulated at a constant level throughout the cell cycle in FR 3T3 cells. Its level and stability increased to different extents in the two types of transformants. However, the formation of complexes between p53 and large-T was modulated by the G2-restricted accumulation of large-T, thus leading to a differential increase in the levels of p53 both in exponentially growing cells and along the cell cycle. This increase in the levels of p53 appeared to be regulated at a post-transcriptional level.

Animals↗

PubMed1984

Cell cycle-dependent expression of early viral genes in one group of simian virus 40-transformed rat cells.

SV40-transformed FR 3T3 rat cells were previously shown to exhibit different patterns of accumulation of the virus-coded T-antigen. One group of transformants accumulates T-antigen throughout the cell cycle, whereas in another group, only the cells in the G2 phase of the cell cycle are stained by immunofluorescence with anti-T antigen antibodies. We investigated the mechanism involved by determining the amounts of early SV40 RNA during the cell cycle. Cells in the various phases of the cell cycle were sorted from an asynchronously growing population using a flow cytofluorimeter. Determination of the amounts of viral RNA in the different nuclear and cytoplasmic RNA fractions showed that in transformants with a G2-restricted accumulation of T-antigen, viral RNA was present in G2, to some extent in S, but could not be detected in cells in G1. In contrast, equivalent amounts of viral RNA were detected in all the phases of the cell cycle in the other group of transformants. Cell sorting, performed after pulse-labeling the cells for 2 h with [35S]methionine, confirmed that translation of the viral mRNAs occurred only in G2 in the first group of transformants, and throughout the cell cycle in the second group.

Animals↗