Biomedical subjects

S Plaisance

Publications and source records attributed to S Plaisance.

27 records · Page 2Linked to original sources

PubMed1993

Organization of the human CD9 gene.

The CD9 antigen was originally described as a 24-kDa molecule present on B-lineage-derived acute lymphoblastic leukemia cells and developing B lymphocytes. Platelets also express a large amount of CD9 antigen and can be activated by CD9 antibodies. We report here the structure of the CD9 gene, which is composed of 8 exons spanning more than 20 kb. There is no TATA or CAAT box in the 5'-flanking domain of the CD9 gene, but a 120-bp region extremely rich in C and G (88%) contains several Sp 1 binding sites and a consensus site for the binding of zinc-finger proteins of the Krox/EGR family. The CD9 antigen belongs to a new cell surface protein family. The organization of its gene closely resembles the organization of the genes for two other members of this protein family, TAPA1 and CD63, which share with CD9 respectively 45 and 25% identity at the amino acid level.

Amino Acid Sequence↗

PubMed1993

The IL-2 receptor present on human embryonic fibroblasts is functional in the absence of P64/IL-2R gamma chain.

In this study, we have investigated the IL-2R gamma gene expression in several human embryonic fibroblasts which express other components of the IL-2 receptor (IL-2R). Polymerase chain reaction did not allow us to detect IL-2R gamma transcripts in these cells but the functionality of the IL-2R alpha beta was not affected. Indeed, in the human IL-2R alpha+beta+gamma- embryonic lung fibroblasts ICIG-7, IL-2 induced identical phenomena to those previously reported in lymphoid cells: rapid internalization of the IL-2R alpha beta-IL-2 complex, specific phosphorylation of cellular proteins (56 and 38 kDa) and up-regulation of ICAM-1 expression. IL-2 induction of ICAM-1 was only observed in sparse cultures and for IL-2 concentrations over 180 pM. We have also observed, in these fibroblastic cells, the up-regulation of ICAM-2 expression by IL-2, both in sparse and dense cultures. These data show that p64/IL-2R gamma expression in human embryonic fibroblasts does not correlate with the ability of the IL-2R to deliver a biological signal.

Amino Acid Sequence↗

PubMed1993

Human melanoma cell line M14 secretes a functional interleukin 2.

Interleukin 2 (IL2) is an important regulator of the immune system. In this report, we have analysed five human melanoma cell lines expressing the IL2R for their ability to secrete IL2. In the M14 melanoma cell line, we observed the appearance of the 0.9 kb transcript specific for the IL2 gene, 72 h after subculture, and the secretion of a biologically active IL2 which specifically sustains the proliferation of the IL2 dependent murine lymphoid cell line CTLL2. In M14 cells, IL2 gene activation is transient as in lymphoid cells but is not inhibited by the immunosuppressive drugs cyclosporine-A and FK506 which are effective on PHA-blasts. In M14 cells, recombinant IL2 (36 pM) induces the down modulation of ICAM-1 expression at the surface of M14 cells. Overnight incubation of these cells with polyclonal anti-IL2 antibodies leads to an increased expression of ICAM-1 and a decreased membrane detection of the IL2R alpha, suggesting the existence of an autocrine/paracrine loop involved in the surface expression of these antigens. A decreased expression of the ICAM-1 protein could help some melanoma cells to escape from cytolytic recognition and therefore favour their metastasis.

Cell Adhesion Molecules↗

PubMed1992

Receptors for interleukin 2 on human squamous cell carcinoma cell lines and tumor in situ.

Several human head and neck squamous carcinoma cell lines were found to bind 125I-labeled or fluorescein-labeled interleukin 2 (IL-2). This binding was inhibited by an excess of cold ligand, IL-2, and by anti-p55 and anti-p70 monoclonal antibodies to the alpha and beta chains, respectively, of the IL-2 receptor (IL-2R). A small number (300/cell) of high-affinity IL-2R (2 x 10(-12) M) and a larger number (> 13,000/cells) of intermediate-affinity IL-2R (3 x 10(-10) M) were present on these tumor cells. By affinity cross-linking, tumor cells were shown to bind 125I-IL-2 to a M(r) 66,000 and 55,000 doublet peptide. The alpha and beta chains of the IL-2R also were detected on the surface of cultured tumor cells using the relevant monoclonal antibodies and flow cytometry. Immunoperoxidase staining with anti-p70 monoclonal antibody confirmed the expression of IL-2R on squamous cell carcinomas of the head and neck in situ. The presence of transcripts for p55/IL-2R-alpha and p70/IL-2R-beta in PCI-1 cells was confirmed by the polymerase chain reaction followed by hybridization to the IL-2R-alpha complementary DNA probe or IL-2R-beta complementary DNA probe, respectively. Our observations demonstrate that intermediate-affinity and high-affinity IL-2Rs are expressed on some human squamous cell carcinomas of the head and neck and that the receptors are functional, because growth of these tumor cell lines can be directly inhibited by exogenously supplied IL-2. The presence of IL-2R on human solid tumors could be important to consider, in addition to immunomodulatory effects of IL-2, in developing optimal therapeutic strategies for the administration of IL-2 to patients with cancer.

Antibodies, Monoclonal↗

PubMed1992

Expression of the interleukin-2 receptor on human fibroblasts and its biological significance.

In this study, we have investigated the expression of the alpha and beta chains of the IL-2 receptor (IL-2R alpha, IL-2R beta) both at the membrane and at transcriptional levels during the lifespan of human embryonic fibroblasts. Here we show that the mAbs IOT14 and MIK beta 1 directed against the IL-2 binding sites of the IL-2R alpha and IL-2R beta respectively, stain human embryonic fibroblasts early in their life span. Data from [125I]rIL2 cross-linking experiments show the simultaneous expression of two IL-2 binding peptides of 70 and 55 kDa respectively on embryonic young fibroblasts as on lymphoid activated cells. The p55 and the p70 IL-2 binding peptides are shown to be specific for the IL-2R alpha and to the IL-2R beta by the finding that these bands are abolished by excess amounts of cold IL-2 and mAbs directed against the IL-2 binding sites of the alpha and beta chains. Scatchard analysis after [125I]IL-2 labelling shows the presence of both high affinity (150 sites with a Kd of 147 pM) and low affinity (1100 sites with a Kd of 4 nM) IL-2 binding sites. Northern blot and dot blot analysis show the presence of specific transcripts for the IL-2R alpha and IL-2R beta genes in early passaged fibroblasts. By contrast, in senescent cultures, only the IL-2R beta transcript were detected. Finally, IL-2 at low concentrations (36 pM) down modulates the level of the intercellular adhesion molecule ICAM-1 in young but not in senescent cultures.(ABSTRACT TRUNCATED AT 250 WORDS)

Cell Adhesion Molecules↗

PubMedDate not supplied

Purification and characterization of a factor which inhibits retrovirus replication.

Chick embryo cells (CEC) secrete a factor which inhibits HIV1 replication. Non-productive infection of CEC with vesicular stomatitis virus increases 5-10-fold the synthesis of this factor. After purification by FPLC the biological activity is associated with a heat-resistant protein of approximately 150 kDa, composed of two subunits of 70 and 58 kDa and charged negatively. Monoclonal antibodies raised against this protein block the inhibitory activity of the purified protein and react with the 150-kDa and 58-kDa proteins in Western blots.

Animals↗

PubMedDate not supplied

Replication of human immunodeficiency virus in HL-60 cells.

HL-60 cells carrying the CD4 marker could be productively infected with human immunodeficiency virus (HIV) but did not form syncytia, though 11-14 days p.i., there was a transient decrease in cell multiplication and viability. After prolonged passage, a subpopulation of HL-60 cells was selected. The virus produced differed from the initial input virus grown on CEM cells: the virions lacked knobs, were either empty or had abnormal cores, had a higher ratio p24/gp41,gp110 and were less infectious. After prolonged passage, virus was produced which was fully infectious for CEM but not for fresh HL-60 cells, and which ressembled the input virus with respect to morphology and p24/gp41,gp110 ratio.

Antigens, Differentiation↗

PubMedDate not supplied

Expression of IL-2 receptors in human melanoma cells.

Melanoma cells can secrete several cytokines and express various cell surface molecules, such as the intercellular adhesion molecule ICAM-1, class II histocompatibility antigens, and the CALLA antigen, typically found in cells of the immune system. We have investigated the possible expression of interleukin-2 (IL-2) receptors in melanoma using monoclonal antibodies specific for the p55/alpha chain (TAC antigen) and the p75/beta subunit. Flow cytometric analysis of cultured melanoma cells showed the presence of low levels of the TAC antigen and of the beta chain on the surface of several cell lines. Similar results were obtained in vivo by immunohistochemistry on cryosections prepared from cutaneous and ocular melanoma explants. Positive staining was observed for the alpha chain of the IL-2 receptor in a high percentage of tumour cells. The beta chain could also be detected, although in a limited number of specimens. Analysis of RNA from melanoma cell lines by Northern blot showed the presence of typical 4 Kb transcripts for the p75 subunit, while low-abundance message for the p55 chain could be detected using combined reverse transcription/polymerase chain reaction analysis. Together, these results suggest that melanoma cells may express high affinity receptors for IL-2.

Antibodies, Monoclonal↗

PubMedDate not supplied

TNF-induced intracellular signaling leading to gene induction or to cytotoxicity by necrosis or by apoptosis.

TNF-induced apoptosis, e.g. in murine PC60 cells, requires the TNF receptor p55 (TNF-R55) and the TNF receptor p75 (TNF-R75); the latter even does not have to be triggered. The intracellular domain of TNF-R55 can be activated in the cytosol by linking it to the trimeric CAT protein; induction of this fusion protein leads to a full TNF response. A new MAP kinase, p38, has been shown to be also activated by TNF. This activation is essential for gene induction, but not for cytotoxicity in L929 cells. TNF treatment of L929 leads to reactive oxygen formation in the mitochondria, resulting in cell death by necrosis. TNF treatment of many other cell types results in apoptosis, and this process involves activation of one or more ICE homologs (IHO). In the mouse, seven cysteine proteases of the IHO family have been cloned and partially characterized. One or more of these IHOs is involved in cell killing by proteolysis of critical substrate(s). One substrate, which may be a key effector molecule in the apoptotic process, is PITSLRE kinase.

Animals↗