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J Marvel

Publications and source records attributed to J Marvel.

At least 37 records · Page 2Linked to original sources
PubMed1994

Interleukin-3 and Bcl-2 cooperatively inhibit etoposide-induced apoptosis in a murine pre-B cell line.

Murine bone marrow-derived hemopoietic cells, dependent on interleukin (IL)-3 for their growth in culture, undergo programmed cell death, or apoptosis, upon cytokine withdrawal. The topoisomerase II inhibitor etoposide causes a more rapid onset of apoptosis in the IL-3-dependent cell line BAF3, deprived of IL-3. This acceleration of apoptosis by etoposide is prevented by inhibitors of RNA and protein synthesis and by the nucleases inhibitor aurintricarboxylic acid. The presence of IL-3 or overexpression of the oncogene bcl-2 caused a marked delay in the induction of apoptosis by etoposide, acting in a cooperative manner. The time at which the apoptotic program is irreversible is close to the induction of endonuclease activity as indicated by the effect of the delayed addition of either IL-3 or aurintricarboxylic acid on the onset of apoptosis, suggesting the importance of endonuclease activation in the development of apoptosis in hemopoietic cells.

Animals↗
PubMed1994

Growth factor starvation of bcl-2 overexpressing murine bone marrow cells induced refractoriness to IL-3 stimulation of proliferation.

Murine bone-marrow derived BAF3 cells, over-expressing the human Bcl-2 gene product, showed considerably delayed onset of apoptosis when deprived of IL-3. Such Bcl-2-BAF3 cells arrested rapidly in the G1 phase of the cell cycle upon IL-3 removal, then became refractory to IL-3 re-stimulation. The delay in IL-3 induced proliferation of Bcl-2 over-expressing cells was due to down-regulation of a specific signalling pathway. In the refractory cells, IL-3 was able to stimulate protein tyrosine phosphorylation and c-myc mRNA accumulation, but not rapid Erk2 activation or cdc2 mRNA accumulation.

Animals↗
PubMed1993

Interleukin 2 activates extracellular signal-regulated protein kinase 2.

Interleukin 2 (IL-2) stimulated activation of the 42-kD extracellular signal-regulated kinase 2 (Erk2) in murine IL-3-dependent cells, expressing either high or intermediate affinity IL-2 receptors. Activation was both rapid, occurring within 5 min of IL-2 addition, and prolonged, remaining elevated for 30 min. Activation of Erk2 appeared to be necessary for IL-2 stimulation of proliferation, as deletion of a region of the cytoplasmic domain of the IL-2 receptor beta chain, essential for IL-2 stimulation of proliferation, abolished Erk2 activation by IL-2. Furthermore, cells that had been deprived of cytokine for 24 h were then refractory to IL-2 stimulation of both Erk2 activity and proliferation. However, elevation of Erk2 activity was not sufficient to stimulate proliferation, as protein kinase C activation stimulated Erk2 activity but not DNA synthesis. Also, cells exposed to IL-2 in the presence of rapamycin showed full Erk2 activation but not DNA synthesis. These data suggest that IL-2 must stimulate both Erk2 activity and a further pathway(s) to trigger cell proliferation.

Animals↗
PubMed1993

Bcl-2 oncogene protects a bone marrow-derived pre-B-cell line from 5'-fluor,2'-deoxyuridine-induced apoptosis.

The bcl-2 protooncogene has been shown to protect haemopoietic precursors from programmed cell death after the removal of interleukin-3 (IL3). In the present report we show evidence that overexpression of bcl-2 in the pre-B-cell line BAF3 protects cells from apoptosis induced by treatment with the thymydilate synthase inhibitor 5'-fluor,2'-deoxyuridine (FDUR) in the presence of IL-3. Dose-response experiments analyzing the dependence of cell death on drug concentration indicated a marked resistance of BAF3bcl-2 to FDUR treatment. Cleavage of DNA into oligonucleosome-length fragments, a characteristic of apoptosis, was observed in BAF3 cells and inhibited in the cells overexpressing bcl-2. We have determined variations in the dATP and dTTP pools after FDUR treatment. Interestingly, no differences were found between both cells in the kinetics of changes in dNTP pools. Therefore, the protective effect of the Bcl-2 protein on apoptosis induced by dNTP unbalance must be ascribed to a step downstream of perturbations in the synthesis of DNA precursors and before activation of endonucleolytic cleavage of chromatin.

Animals↗
PubMed1993

Hyper-reactivity of mouse CD45RA- T cells.

Mouse CD4 T cells have been partitioned into CD45RA and CD45RA- subpopulations by means of the monoclonal antibody 14.8. The CD45RA- subpopulation proliferated more actively and generated more interleukin-4 (IL-4) in response to stimulation with anti-CD3 antibody and phytohemagglutinin, and more IL-2 in response to anti-CD3. This subpopulation is therefore hyper-reactive to these polyclonal stimulators, but does not show the bias towards T helper type 2 activity that has been found in studies with other related CD45 isoforms. No evidence of suppression was obtained by comparing proliferation of CD45RA- cells in the presence and absence of CD45RA cells. Thus mouse CD4 T cells behave in these respects similarly to those of man, as is evident in a brief review of the quiescence-activation-quiescence cycle in the two species.

Animals↗
PubMed1993

CD45RA+ T cells: not simple virgins.

1. The T cells which mediate immunological memory remain elusive. Identification of such cells would open the door to increasingly specific immunotherapy in areas such as transplantation and autoimmunity. 2. Over the last few years attempts have been made to identify phenotypic markers which can distinguish naive or virgin T cells from primed or memory ones. In humans, great hopes were raised when it was shown that the level of expression of the higher-molecular-mass isoforms (CD45RA) of the tyrosine phosphatase, CD45, correlated with previous exposure to antigen. 4. However, our studies in the mouse and more recent studies in rat and human suggest that expression of CD45RA more closely correlates with the state of responsiveness of the T cell. 5. Thus, with time, activated/memory T cells return to a state of quiescence or hypo-responsiveness and express high levels of CD45RA. Hence, not all CD45RA+ T cells are virgins.

Aging↗
PubMed1993

Role of CD4+CD45RA+ T cells in the development of autoimmune diabetes in the non-obese diabetic (NOD) mouse.

The non-obese diabetic (NOD) mouse spontaneously develops a T cell-mediated autoimmune disease, sharing many features with human insulin-dependent diabetes mellitus (IDDM), leading to insulin-secreting beta cell destruction. The role of CD4+ T cells has been evidenced at two levels. First, CD4+ T cells from diabetic animals are required to transfer diabetes to non-diabetic recipients in conjunction with CD8+ effector T cells. Second, suppressive CD4+ T cells have been characterized in non-diabetic NOD mice. T cells with different functions can thus share the CD4+ phenotype. Since CD4+ T cells can be divided into at least two subgroups on the basis of CD45 isoform expression, we evaluated the distribution of CD4+ T cells expressing the CD45RA isoform on NOD mouse thymocytes and peripheral T cells. The percentage of CD45RA+ cells was dramatically increased among the most mature CD3bright thymocytes and among CD4+ T cells in lymph nodes of the NOD mouse as compared with control strains. This increase was related to the development of insulitis. Interestingly, the CD45RA isoform was expressed on most CD4+ T cells invading the islets. In vivo treatment with an anti-CD45RA mAb prevented the development of insulitis and spontaneous diabetes in female animals but not the transfer of diabetes by T cells collected from diabetic NOD donors. These results indicate that anti-CD45RA mAb is only effective if given before the full commitment of effector T cells to the destruction of islet beta cells. Thus CD4+CD45RA+ T cells play a key role in early activation steps of anti-islet immunity.

Animals↗
PubMed1993

Paratracheal lymph node dissection for carcinoma of the larynx, hypopharynx, and cervical esophagus.

Paratracheal lymph node (PTLN) metastasis has been implicated as an etiologic factor in peristomal recurrence after laryngectomy. To determine the relationship between the primary site, the risk of peristomal recurrence, and the prognostic significance of PTLN metastasis, the medical records of 645 patients who underwent total laryngectomy between 1978 and 1990 for squamous cell carcinoma of the larynx, hypopharynx, and cervical esophagus were reviewed. Criteria for inclusion were the surgeon's description of PTLN dissection and hemi- or total thyroidectomy, as well as gross and microscopic pathologic identification of PTLNs. These requirements were fulfilled in 141 patients, who composed the cohort analyzed. There were 117 males and 24 females, with a median followup of 20 months (range, 1 to 94 months). Fifty-three patients were treated previously; among these, 21 underwent tracheostomy before laryngectomy. The primary site of origin was the larynx in 64.5% of patients, the hypopharynx in 25.5%, and the cervical esophagus in 9.9%. Of the patients with endolaryngeal primary tumors, 33% had subglottic extension. Postoperative stomal irradiation was administered to 61 patients. The mean number of PTLNs removed was 3.9 (range, 1 to 30), and metastasis was present in 29 patients (20.5%). PTLN metastasis by primary tumor site was the cervical esophagus, 10 of 14 (71.4%) (p < 0.001); the larynx, 16 of 91 (17.6%); and the hypopharynx, 3 of 36 (8.3%). Of the 30 patients with subglottic extension, eight (26.7%) had PTLN metastases. Peristomal recurrences developed in six of 141 patients (4%), and metastasis to PTLNs was identified in one third of these patients. No peristomal recurrence developed in any of the patients who received postoperative radiotherapy to the stoma (p = 0.057). Survival was significantly reduced by the presence of PTLN metastases.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Interleukin 3 protects murine bone marrow cells from apoptosis induced by DNA damaging agents.

Murine bone marrow-derived cells, dependent on interleukin 3 (IL-3) for their growth in culture, undergo programmed cell, or apoptosis, upon cytokine withdrawal. Here it is reported that a variety of DNA damaging agents cause a more rapid onset of apoptosis in a factor-dependent cell line, BAF3, deprived of IL-3. In contrast, when cultured in the presence of IL-3, or other growth promoting factors, BAF3 cells are highly resistant to X-irradiation and the cytotoxic drugs etoposide and cisplatin. Overexpression of the bcl2 gene product also protects BAF3 cells from DNA damage. The presence of IL-3 is not required during the initial events of DNA damage or its repair. In the absence of IL-3, cells still complete the repair of DNA breaks within 15 min, and continue to cycle for 5 h. At this time, IL-3 is necessary to prevent the accelerated onset of DNA cleavage from a G2 arrest point.

Animals↗
PubMed1992

Memory in helper T cells of minor histocompatibility antigens, revealed in vivo by alloimmunizations in combination with Thy-1 antigen.

A cooperative antibody response in which T helper (Th) cells recognize minor histocompatibility antigens (mha) and B cells recognize Thy-1 antigen, is used to explore memory in the T cell compartment. In contrast to B cell memory, Th memory reaches a plateau rapidly, although Th memory of Thy-1 itself (or an associated antigen) behaves exceptionally in this respect. The plateau then extends over several weeks at least. Single mha, among them H-Y, generate detectable memory. Incompatible H-2 antigens, including class I antigens on their own, inhibit this response through what appears to be a mechanism of intracellular antigenic competition. Antigen presentation in this system is by host cells, as judged by lack of donor-specific restriction. Memory resides in both the CD45RA+ and CD45RA- compartments, although the majority of memory Th cells have the latter phenotype.

Animals↗
PubMed1992

Concurrent increases in regional hematocrit and blood flow in diabetic rats: prevention by sorbinil.

These studies were undertaken to investigate the relationship between regional hemodynamic and hemorheological changes in the microvasculature of diabetic rats. Diabetes was induced in male Sprague-Dawley rats by injection of streptozotocin (55 mg/kg body wt). Control rats were injected with vehicle (sodium citrate buffer). A subgroup of diabetic rats was treated with an aldose reductase inhibitor (sorbinil) added to the diet in an amount to provide a daily dose of approximately 0.2 mmol.kg-1.day-1. Three weeks later all animals were anesthetized with thiobutabarbital sodium (Inactin, 100 mg/kg injected intraperitoneally) for assessment of blood flow (by injection of 15 microns microspheres) and regional hematocrit (determined by isotope-dilution techniques using 51Cr-labeled red blood cells and 125I-labeled bovine serum albumin) in selected tissues. The hematocrit in arterial blood samples was identical (approximately 46%) in controls and in diabetics. Regional hematocrits were much lower than arterial hematocrits in control rats and ranged from approximately 20% in ocular tissues, sciatic nerve, diaphragm, and skin to approximately 30% in brain, skeletal muscle, heart, and fat. Hematocrits of diabetic rats were markedly increased in ocular tissues, sciatic nerve, and skin but not in brain, heart, or skeletal muscle. These increases in regional hematocrit were associated with increases in blood flow and were largely prevented by sorbinil. Diabetes induced significant decreases in the mean transit times for whole blood and erythrocytes in all tissues examined except brain, retina, and skin.(ABSTRACT TRUNCATED AT 250 WORDS)

Aldehyde Reductase↗
PubMed1991

Evidence that the CD45 phosphatase regulates the activity of the phospholipase C in mouse T lymphocytes.

The importance of the tyrosine phosphatase CD45 in the regulation of lymphocyte activation was first demonstrated using antibodies against the extracellular domain of CD45 in functional assays. More recently it was reported that CD45-negative mutants were nonresponsive to stimulation through the T cell receptor-CD3 complex. We have studied the effect of CD45 cross-linking on the early signals induced by CD3 in mouse T cells. We show that CD45 cross-linking inhibits the increase in inositol phosphates and cytoplasmic Ca2+ induced by cross-linking of CD3. This indicates that CD45 is involved in the regulation of phospholipase C.

Animals↗
PubMed1991

In the mouse the maturation stage of the peripheral CD4+ CD45RA+ subset is different from that of the CD8+ CD45RA+ subset.

In vitro studies have suggested that the presence of CD45RA on subsets of CD4 and CD8 cells defines naive T cells and that, in response to antigen, CD45RA+ cells become CD45RA- along a differentiation pathway. To test the hypothesis that CD45RA+ cells are naive cells which have just left the thymus, young mice were thymectomized. This would be predicted to lead to a fall in the size of the peripheral pool of CD45RA+ T cells. However, the changes in the size of this pool would also be dependent on the life-span and self renewal capacity of the CD45RA+ T cells in the periphery. Therefore, to test the contribution of the thymus to the peripheral CD45RA+ pool, the percentage of CD45RA+ cells among spleen lymphocyte subsets was studied from 10 days up to 2 years of age in thymectomized and control mice. We also studied the expression of the memory marker CD44 on the CD45RA subsets of CD4 and CD8 cells, as well as the effect of in vitro activation on expression of CD45RA. Our results show that CD8+ CD45RA+ cells are mainly CD44- and their maintenance is dependent on the presence of the thymus. In contrast, the majority of CD4+ CD45RA+ are CD44+ and are not affected by thymectomy. This indicates that the maturation stage of CD8+ CD45RA+ cells is different from that of CD4+ CD45RA+ cells.

Aging↗
PubMed1991

The CD45RA molecule is expressed in naive murine CTL precursors but absent in memory and effector CTL.

We have studied the expression of the CD45RA molecule in murine cytotoxic T lymphocytes (CTL) specific for the allogeneic H-2Kb molecule at different stages of differentiation. The CD45RA phenotype of naive H-2Kb-specific CTL precursors has been determined using primary in vitro CTL responses. For the analysis of memory CTL we have immunized mice in vivo followed by restimulation in vitro. We have also determined the CD45RA expression at the CTL effector stage. Our results show that among naive CD8+ T cells both the CD45RA+ and the CD45RA- subpopulations can mount Kb-specific CTL responses. In contrast, memory CTL responses are mediated only by the CD8+ CD45RA+ T cell subpopulation. Similarly, effector CTL are CD8+ CD45RA- while the CD8+ CD45RA+ subpopulation does not exhibit specific cytolytic activity. The data indicate that CD45RA expression changes during CTL differentiation and that memory as well as effector CTL lack this marker.

Animals↗
PubMed1991

CD45RA antibodies split the CD3bright T cell subset.

Thymocyte subsets have been well characterized on the basis of CD4 and CD8 antigen expression. Recently, the use of anti-CD3 antibodies has allowed more precise phenotyping of these subsets. The most immature T cell precursors are largely CD3-CD4-CD8-, while the most mature are CD3brightCD4+CD8- or CD3brightCD4-CD8+. Moreover, the expression of CD45RA on thymocytes appears to define a progenitor population and may define a continuous lineage of cells. Using a panel of CD45RA antibodies, we have further characterized the CD45RA+ thymocyte population in the murine system. The size of this subset is greatly enhanced in cortisone-treated mice and in sublethally irradiated mice. Moreover, the CD45RA+ population is present early in foetal life and is maintained thereafter. Using three-colour immunofluorescence, we show that (i) while most CD45RA+ cells are present amongst the CD4-CD8- thymocyte subset in the normal thymus, after cortisone treatment or irradiation, all four thymocyte subsets co-express significant amounts of CD45RA. This suggests that not only progenitor cells but also the mature population which can survive such manipulation are CD45RA+; and (ii) a large proportion of CD45RA+ cells are CD3bright and this subset is represented in the thymus at all stages of maturation tested. These data suggest that a proportion of TCR-gamma delta + CD3+ cells in the fetus as well as of TCR-alpha beta+ CD3+ cells in the adult co-express CD45RA.

Animals↗
PubMed1990

CD45RA is detected in all thymocyte subsets defined by CD4 and CD8 by using three-colour flow cytometry.

In the mouse, using three-colour flow cytometry, the presence of CD45RA+ cells is demonstrated amongst all of the thymocyte subsets defined by expression of CD4 and CD8, i.e. amongst the double negatives, immature CD8 single positives, double-positive blasts and CD4 and CD8 single positives. This evidence is compatible with the existence of a continuous lineage of T cells expressing CD45RA which would develop from double-negative to mature single-positive T cells.

Aging↗