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G Rousselet

Publications and source records attributed to G Rousselet.

At least 37 records · Page 2Linked to original sources
PubMed1995

The fate of human CD77+ germinal center B lymphocytes after rescue from apoptosis.

Germinal center (GC) B lymphocytes, defined by various criteria, have been shown to spontaneously undergo apoptosis in vitro unless they receive a positive signal. This rescue signal seems to be a multi-component process which involves not only the B cell receptor but also other cell surface receptors such as the CD40 antigen. In previous studies, we have shown that expression of the CD77 antigen is restricted to GC B lymphocytes and that CD77+ cells readily enter programmed cell death when cultured in vitro. In order to better characterize the CD77+ B lymphocytes, we have investigated the fate of these cells after rescue from apoptosis. Survival of CD77+ cells was achieved either with a combination of anti-CD40 mAb and IL4 (the CD40 system developed by Banchereau et al., (1991) Science 251, 70-72) or EBV infection. After 4 days of culture, similar phenotypic and functional changes of the CD77+ lymphocytes were observed in both systems: CD77 antigen was down-regulated, CD23 antigen which was originally negative became strongly expressed and the expression of CD38 and CD20 remained constant. Furthermore, large quantities of soluble CD23 were produced by the surviving cells. These results indicate that CD77 antigen is expressed by GC B cells which are highly susceptible to enter apoptosis but which are not doomed to die.

Antibodies, Monoclonal↗
PubMed1994

Cloning and functional expression of a urea transporter from human bone marrow cells.

A rapid passive urea transport has been previously described in the mammalian renal inner medullary collecting duct epithelial cells and in mammalian erythrocytes. Recently, a vasopressin-regulated urea transporter (UT2) has been cloned from a rabbit kidney medullary cDNA library (You, G., Smith, C. P., Kanai, Y., Lee, W. S., Stelzner, M., and Hediger, M. A. (1993) Nature 365, 844-847). We now report the cloning and characterization of a complementary DNA (HUT11) encoding an urea transporter isolated from a human bone marrow library. It encodes a 43,000-Da polypeptide of 391 amino acids that exhibited 63% sequence identity with the rabbit urea transporter and a similar membrane topology. HUT11 carries 2 putative glycosylation sites and 10 cysteines, of which only 7 are conserved at an equivalent position in UT2. HUT11 transcripts have been identified in human erythroid and renal tissues. Expression studies in Xenopus oocytes demonstrated that HUT11 mediates a facilitated urea transport that was inhibited, as described in mammalian erythrocytes, by very low concentrations of phloretin, p-chloromercuribenzene sulfonate, and urea analogues. No unidirectional movements of charged molecules, glycerol, or water were associated with HUT11 expression in oocytes. These findings suggest that HUT11 is most likely responsible for the facilitated urea transport in human red blood cells.

4-Chloromercuribenzenesulfonate↗
PubMed1994

Sequence and functional expression of an amphibian water channel, FA-CHIP: a new member of the MIP family.

A new member of the family of water channel proteins (aquaporin-CHIP) related to the major intrinsic protein (MIP) family is described. The cDNA coding for this amphibian CHIP was cloned from frog (Rana esculenta) urinary bladder, a model for the kidney collecting duct, using a RT-PCR cloning strategy. The encoded protein, designated FA-CHIP (frog aquaporin-CHIP), shows 77.4%, 42.4% and 35.6% identity with the three proteins now referred to as the aquaporins of the MIP family, i.e., human CHIP28, WCH-CD and gamma-TIP, respectively. Xenopus leavis injected with FA-CHIP cRNA exhibited a marked increase of the osmotic water permeability.

Amino Acid Sequence↗
PubMed1993

Cytogenetic studies in three xenografted nasopharyngeal carcinomas.

Cytogenetics results of three xenografted nasopharyngeal carcinomas (NPC) are reported. One (C15) was almost diploid and had only an isochromosome 1q, trisomy 2, and loss of chromosome X. The two other tumors, C17 and C19, were hypodiploid and had complex karyotypes with some variations. Nonrandom structural abnormalities of chromosomes 1, 3, 8, and 17 were observed. A correlation between a del(17)(p11-12) observed in C17 and loss of both alleles of p53 recently shown in this tumor is emphasized.

Adolescent↗
PubMed1993

Clinical implications of the serum level of CD23 in patients with undifferentiated nasopharyngeal carcinoma.

PURPOSE: In contrast with other carcinoma cells, cells from nude mice transplanted undifferentiated carcinoma of nasopharyngeal type (UCNT) release the soluble fragment of the CD23 antigen (sCD23). We sought to study the level of sCD23 in sera of untreated UCNT patients. PATIENTS AND METHODS: Pretherapeutic sera from 65 consecutive, locally advanced, initially nonmetastatic UCNT patients were assayed for sCD23. Patients were treated with a neoadjuvant chemotherapy/full-dose radiotherapy sequence. The mean follow-up duration is 50.5 months (range, 28 to 77). The Cox proportional hazards model was used to study the association between sCD23 levels and clinical signs and disease evolution. RESULTS: sCD23 levels showed an association with disease-free survival (DFS; P = .08) and overall survival (OVS; P = .08). Patients with sCD23 levels greater than a cutoff value of 0.6 ng/mL (greater cutoffs were found to be equally significant, but less sensitive), have a relative risk (RR) of relapse of 3.3 (95% confidence interval, 1.6 to 6.9; P = .002), and an RR of death of 2.9 (95% confidence interval, 1.2 to 7.3; P = .02), when taking other prognostic factors into account. CD23 does not correlate with either the response to treatment or the development of metastases, but appears to be related to local control (cutoff, 0.6 ng/mL; RR = 5.1 [95% confidence interval, 1.2 to 21.7]; P = .02). CONCLUSION: The serum level of sCD23 appears to be an independent prognostic factor for initially nonmetastatic, locally advanced UCNT patients, treated with chemotherapy and radiotherapy. Our data indicate an association between this marker and local relapses. Thus, a simple enzyme-linked immunoadsorbent assay (ELISA) could help to identify a high-risk group among nonmetastatic UCNT patients. CD23 could be a marker for two groups of UCNT tumors, with distinct biologic characteristics and clinical behaviors.

Adolescent↗
PubMed1993

Leukemoid reaction, bone marrow invasion, fever of unknown origin, and metastatic pattern in the natural history of advanced undifferentiated carcinoma of nasopharyngeal type: a review of 255 consecutive cases.

PURPOSE: This study is an analysis of frequency and relationship regarding two undifferentiated carcinoma of nasopharyngeal type (UCNT)-associated paraneoplastic syndromes (PNS): leukemoid reaction (LR) and fever of unknown origin (FUO) with bone marrow invasion (BMI) and metastatic pattern. PATIENTS AND METHODS: A consecutive UCNT patient cohort (N = 255) with locally advanced (n = 142) or metastatic (n = 113) disease receiving chemotherapy alone or in combination with radiotherapy was studied. All patients had a complete baseline work-up that included bone marrow biopsy. RESULTS: UCNT has distinctive features among head and neck squamous cell cancers (HNSCC). These include early subclinical dissemination, with 70% of metastases appearing within 18 months of first symptoms. Metastases are common in bone (65% v 25% in HNSCC), liver (29% v 23%), and lung (18% v 84%), and BMI is observed in 25% of UCNT patients with metastases. Metastases likelihood is related to lymph node involvement, with 64% of patients with metastases having N3 disease. Involved lymph nodes in contrasted CT scans revealed hypodensity in 26% of UCNT patients versus 79% in patients with other HNSCC. Hypercalcemia was observed in one case. LR was identified in 41 patients (16%); in 26 of the 41 patients (64%) it was observed concomitant with N3 and/or metastatic disease. FUO was found in 23 patients (9%) and was associated in four instances with BMI and in 17 with LR (in four instances with both). Brain metastases or meningeal carcinomatosis were not observed despite the high rate of skull base compromise. Paraneoplastic signs were observed in 47 of 255 cases (18.5%) and were more frequent in patients with metastases. However, PNS were observed in 15 patients with negative metastases work-up. CONCLUSION: The PNS described could help in the diagnosis and follow-up of UCNT patients because they may be the first manifestation of the disease or may reappear with relapse. BMI is a frequent finding in patients with metastases and is unrelated to PNS.

Adolescent↗
PubMed1990

Structure and regulation of the blast-2/CD23 antigen in epithelial cells from nasopharyngeal carcinoma.

Undifferentiated nasopharyngeal carcinoma (NPC) is tightly associated with the Epstein-Barr virus (EBV) and very heavily infiltrated with T lymphocytes. We demonstrated recently that NPC epithelial cells produce immuno-regulatory molecules, including the Blast-2/CD23 antigen, which is induced in B lymphocytes upon infection by EBV. We demonstrate here that CD23 expression is a non-constant but highly specific feature of epithelial cells from NPC. The C15 and C17 NPC tumor cells express mainly the b form of CD23, which is known to be non-lineage-specific and IL-4-inducible. C17 cells were found also to weakly express the a form of CD23, which has been described as B cell-specific. In addition, several factors potentially released in vivo by tumor infiltrating lymphocytes (TILs) are able to regulate CD23 expression in NPC cells. In particular, we found that IL-4 was a potent inducer of CD23 expression in C15 cells, as shown at both the protein and the mRNA levels. These results, together with the already reported expression of class II MHC antigens and the release of IL-1 by NPC cells, suggest that the interactions between TILs and malignant cells are a key factor in NPC pathogenesis and development.

Animals↗
PubMed1990

Stable transfection of Epstein-Barr virus (EBV) nuclear antigen 2 in lymphoma cells containing the EBV P3HR1 genome induces expression of B-cell activation molecules CD21 and CD23.

A set of B-cell activation molecules, including the Epstein-Barr virus (EBV) receptor CR2 (CD21) and the B-cell activation antigen CD23 (Blast2/Fc epsilon RII), is turned on by infecting EBV-negative B-lymphoma cell lines with immortalizing strains of the viruslike B95-8 (BL/B95 cells). This up regulation may represent one of the mechanisms involved in EBV-mediated B-cell immortalization. The P3HR1 nonimmortalizing strain of the virus, which is deleted for the entire Epstein-Barr nuclear antigen 2 (EBNA2) protein open reading frame, is incapable of inducing the expression of CR2 and CD23, suggesting a crucial role for EBNA2 in the activation of these molecules. In addition, lymphoma cells containing the P3HR1 genome (BL/P3HR1 cells) do not express the viral latent membrane protein (LMP), which is regularly expressed in cells infected with immortalizing viral strains. Using electroporation, we have transfected the EBNA2 gene cloned in an episomal vector into BL/P3HR1 cells and have obtained cell clones that stably express the EBNA2 protein. In these clones, EBNA2 expression was associated with an increased amount of CR2 and CD23 steady-state RNAs. Of the three species of CD23 mRNAs described, the Fc epsilon RIIa species was preferentially expressed in these EBNA2-expressing clones. An increased cell surface expression of CR2 but not of CD23 was observed, and the soluble form of CD23 molecule (SCD23) was released. We were, however, not able to detect any expression of LMP in these cell clones. These data demonstrate that EBNA2 gene is able to complement P3HR1 virus latent functions to induce the activation of CR2 and CD23 expression, and they emphasize the role of EBNA2 protein in the modulation of cellular gene implicated in B-cell proliferation and hence in EBV-mediated B-cell immortalization. Nevertheless, EBNA2 expression in BL/P3HR1 cells is not able to restore the level of CR2 and CD23 expression observed in BL/B95 cells, suggesting that other cellular or viral proteins may also have an important role in the activation of these molecules: the viral LMP seems to be a good candidate.

Antigens, CD↗
PubMed1989

Epstein-Barr virus (EBV)-containing nasopharyngeal carcinoma cells express the B-cell activation antigen blast2/CD23 and low levels of the EBV receptor CR2.

Anaplastic nasopharyngeal carcinoma (NPC) cells invariably harbor the Epstein-Barr virus (EBV) genome, an association that is unique among human virus-associated cancers. Although EBV is able to replicate in epithelial cells, results with expression of the EBV receptor (complement receptor type 2 [CR2]; also called CD21) in normal and malignant epithelial cells are conflicting. We grew five different EBV-associated NPC tumors in nude mice, and by using a sensitive transcriptional assay, we detected a very weak transcription signal of the EBV receptor CR2 gene in these cells. This suggests that low levels of EBV receptor may be expressed by malignant epithelial nasopharyngeal cells. The gene coding for Blast2/CD23, a B-cell activation molecule induced by EBV, was transcribed in three of the transplanted NPC tumors. The soluble form of the Blast2/CD23 protein was also detected in medium taken from short-term cultures of the same NPC cell lines. In contrast to the lymphoid system, in which Blast2/CD23 expression is associated with EBV nuclear antigen (EBNA2) expression, no EBNA2 protein could be detected in these NPC epithelial cells. Our study represents the first demonstration of Blast2/CD23 expression in epithelial cells. As the soluble form of the Blast2/CD23 protein possesses growth factor activity associated with EBV-induced B-cell immortalization, these results suggest a possible role for this molecule in the pathogenesis of NPC.

Animals↗