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R Ettinger

Publications and source records attributed to R Ettinger.

At least 19 recordsLinked to original sources
PubMed2001

A critical role for lymphotoxin-beta receptor in the development of diabetes in nonobese diabetic mice.

To assess the role of lymphotoxin-beta receptor (LTbetaR) in diabetes pathogenesis, we expressed an LTbetaR-Fc fusion protein in nonobese diabetic (NOD) mice. The fusion protein was expressed in the embryo, reached high levels for the first 2 wk after birth, and then declined progressively with age. High expression of LTbetaR-Fc blocked diabetes development but not insulitis. After the decline in chimeric protein concentration, mice became diabetic with kinetics similar to the controls. Early expression of fusion protein resulted in disrupted splenic architecture. However, primary follicles and follicular dendritic cells, but not marginal zones, developed in aged mice. Hence, LTbetaR signaling is required for diabetes development and regulates follicular and marginal zone structures via qualitatively or quantitatively distinct mechanisms.

Animals↗
PubMed1998

Effects of tumor necrosis factor and lymphotoxin on peripheral lymphoid tissue development.

Previously, we have reported that neutralization of surface lymphotoxin (LT-alphabeta) in mice which expressed an LT-beta receptor-Fc fusion protein, driven by the cytomegalovirus promoter, resulted in an array of anatomic abnormalities. We now report that mice which express a tumor necrosis factor (TNF) receptor p60-Fc fusion protein (which neutralizes TNF and soluble LT-alpha3 activity) develop unique lymphoid abnormalities. Our data demonstrate that some aspects of peripheral lymphoid organ development require both surface LT-alphabeta and TNF interacting with their specific receptors. However, these related cytokines are also capable of signaling distinct developmental events. Splenic MAdCAM-1 expression, follicular dendritic cell localization and normal Peyer's patch development all require both surface LT-alphabeta and TNF activity. Marginal zone formation and splenic B cell localization primarily require surface LT-alphabeta-LT-beta receptor interactions. Primary follicle formation was dependent upon TNF receptor(s) engagement. Interestingly spleen, lymph nodes and Peyer's patches from TNF receptor p60-Fc-expressing mice all develop different abnormalities, suggesting distinct pathways of development in these lymphoid organs. Thymus development appears to be independent of these signaling pathways. These results demonstrate that TNF and LT are crucial for normal peripheral, but not central lymphoid organ development.

Animals↗
PubMed1996

Disrupted splenic architecture, but normal lymph node development in mice expressing a soluble lymphotoxin-beta receptor-IgG1 fusion protein.

Early in ontogeny, the secondary lymphoid organs become populated with numerous cells of mesodermal origin which forms both the lymphoid and stromal elements. The critical receptor/ligand interactions necessary for lymphoid organogenesis to occur are for the most part unknown. Although lymphotoxin-alpha (LT alpha) has been shown to be required for normal lymph node, Peyer's patch, and splenic development, it is unclear if soluble LT alpha 3, and/or cell-bound lymphotoxin-alpha beta (LT alpha beta) mediate these developmental events. Here we report that blocking LT alpha beta/lymphotoxin-beta receptor (LT beta R) interaction in vivo by generating mice which express a soluble LT beta R-Fc fusion protein driven by the human cytomegalovirus promoter results in an array of anatomic abnormalities affecting both the spleen and Peyer's patches, but not the lymph nodes. These results demonstrate that surface LT alpha beta ligand plays a critical role in normal lymphoid organ development.

Aging↗
PubMed1996

Characterization of lpr-derived T cell hybridomas: Fas-deficient hybridomas are deathless, growth-arrested, and cytotoxic upon activation.

T cell hybridomas that are deathless upon TCR crosslinking were generated from lpr mice. The deathless hybridomas (1.4 and 5D5) expressed extremely low Fas even after anti-CD3 activation, whereas activation-induced cell death (AICD) was observed for Fas-expressing hybridomas. The deathless hybridomas were activated to produce FasL and IL-2, indicating that the intrinsic defect in Fas expression or up-regulation resulted in AICD blockade. The deathless hybridoma cells expressed longer and stronger FasL cytotoxicity than AICD-sensitive hybridomas. Although deathless, activated 5D5 cells were arrested at the G1/S border. Growth arrest lasted for at least 5 days, but some cells eventually recovered and proliferated. The deathless 5D5 cells were used to demonstrate that AICD includes a fratricidal mechanism that kills AICD-sensitive bystanders. The deathless T cell hybridomas are useful tools for studying T cell activation-dependent functions sensitive to AICD.

Animals↗
PubMed1995

Fas ligand-mediated cytotoxicity is directly responsible for apoptosis of normal CD4+ T cells responding to a bacterial superantigen.

Exposure of naive CD4+ T lymphocytes to superantigens such as staphylococcal enterotoxin B (SEB) induces a strong proliferative response. Prolonged exposure or subsequent restimulation of the responding T cell population with SEB leads to the apoptotic events of activation-induced cell death (AICD). However, T cells derived from either Fas-deficient lpr or Fas ligand-deficient gld autoimmune mouse strains, fail to undergo AICD under these conditions. Instead, these autoimmune T cells mount a vigorous proliferative response, suggesting a critical role for Fas/FasL interactions in this form of autoapoptosis. In the current study, we found that SEB-induced AICD was tied to the rapid induction of FasL expression in cells constitutively expressing high levels of Fas. Furthermore, the addition of soluble Fas-IgG fusion protein to the SEB-restimulated cultures blocked AICD and resulted in a 2 degrees proliferative response that was comparable in magnitude and kinetics to that of the lpr and gld T cells. The rapid onset of apoptosis in normal T cells subsequent to restimulation with SEB was in direct contrast to the proliferative response of the initial cultures, even though comparable levels of Fas and FasL RNA were found in T cells after 1 degree and 2 degrees challenge. The clonal expansion of the normal T cells responding to the initial SEB stimulation was, however, dramatically compromised when the normal cells were cocultured with an MRL-lpr responder population; addition of soluble Fas-IgG rescued the normal component of the response. Together, these data demonstrate first, that Fas/FasL interactions are intimately tied to superantigen-induced AICD, a form of autocrine cell death, and second, that FasL-mediated cytotoxicity is responsible for the disappearance of normal CD4+ T cells in lpr cocultures.

Animals↗
PubMed1995

Fas(CD95)/FasL interactions required for programmed cell death after T-cell activation.

Receptor crosslinking of T-cell hybridomas induces cell activation followed by apoptosis. This activation-induced cell death requires de novo synthesis of RNA and proteins, but the actual gene products that provide the death signal have not been identified. We show here that receptor crosslinking induces Fas ligand and upregulates Fas, and that the ensuing engagement of Fas by Fas ligand activates the cell-death programme. Cell death, but not activation, can be selectively prevented by a soluble Fas-immunoglobulin fusion protein. Thus, Fas and Fas ligand are the death-gene products, and their interaction accounts for the molecular mechanism of activation-induced T-cell death.

3T3 Cells↗
PubMed1995

An evaluation of removable partial dentures: a retrospective study.

A 50% sample (N = 100) of all patients aged between 50-70 years at the time of treatment who received RPDs' were interviewed by telephone for 8-10 minutes. The questionnaires evaluated the subjects' denture experience, attitudes to dentures, and satisfaction with them. A large majority were satisfied with their RPD's but a higher proportion of women reported problems with mandibular RPD's. About one third of the group had not returned for recalls. Statistically significant relationships were found which suggested that subjects who were satisfied with their previous dentures were more likely to be satisfied with their replacements, and subjects who removed their RPD's to eat were likely to be dissatisfied with them.

Aged↗
PubMed1994

Participation of target Fas protein in apoptosis pathway induced by CD4+ Th1 and CD8+ cytotoxic T cells.

The results presented here provide evidence that the presence of Fas protein in target cells is essential to permit cytotoxicity (resulting in apoptosis) mediated by cloned CD4+ Th1 cells. Using mitogen-activated B cells as targets, antigen-dependent lysis by CD4+ Th1 effectors was observed with MRL/MpJ+ but not with MRL/MpJ-lpr targets. The congenic MRL/MpJ-lpr strain is defective in Fas expression. Target cells from various lymphoid tissues of C3H.MRL-lpr mice were also resistant to the lectin-dependent cytotoxicity of Th1 effectors, whereas C3H/HeJ targets were sensitive. Moreover, a rapid DNA fragmentation prior to 51Cr release was induced only in C3H/HeJ targets. Thus, cytotoxicity induced by Th1 effectors correlates with target Fas expression. In contrast to Th1 effectors, CD8+ cytotoxic T lymphocytes (CTLs) killed C3H.MRL-lpr targets. When cytotoxicity was assayed in the presence of EGTA and MgCl2, which chelates extracellular Ca2+ [(Ca2+)ext], only C3H.MRL-lpr targets became resistant to CD8+ CTLs. This (Ca2+)ext-independent cytotoxicity of both Th1 and CD8+ effectors could be inhibited with unlabeled C3H/HeJ thymocytes or with a transfectoma carrying a murine Fas-human mu gene construct. In comparison, C3H.MRL-lpr thymocytes and the nontransfected parental cell line were poor inhibitors. Our study demonstrates that CD4+ Th1 cells and CD8+ CTLs differ in their (Ca2+)ext-dependent cytotoxicity but share a (Ca2+)ext-independent cytotoxicity that requires participation of Fas molecules for cytotoxic signal transduction leading to target apoptosis.

Animals↗
PubMed1994

Functional distinctions between MRL-lpr and MRL-gld lymphocytes. Normal cells reverse the gld but not lpr immunoregulatory defect.

Homozygosity for either of the autosomal recessive mutations, lpr or gld, confers an autoimmune syndrome characterized by massive lymphoid hyperplasia and extensive autoantibody production. Despite the similarities in disease progression, functional distinctions in these genetic defects have been observed in bone marrow transplantation studies. To elucidate the mechanisms responsible for the aberrant immune phenotype of these strains, we analyzed interactions between normal T cells and T cells from the two autoimmune strains with regard to their in vitro responses to autologous and allogeneic stimuli and in an in vivo bone marrow transplantation model. Despite similar propensities for lpr and gld T cells to spontaneously proliferate in vitro in response to autologous class II Ag, a dramatic difference in their immunoregulatory properties was found when mixtures of normal and autoimmune CD4+ responder cells were challenged with an allogeneic stimulus. T cells from the lpr, but not gld, mice blocked the normal T cell component of the response. In vivo, the ability of lpr stem cells to trigger a wasting syndrome when transplanted into normal irradiated recipients could not be prevented by including normal stem cells in the inoculum; however, the ability of gld stem cells to transfer the gld-lymphoproliferative syndrome to normal recipients could be prevented with the addition of normal stem cells. These results support a model whereby the lpr and gld strains are defective in reciprocal components of a down-regulatory signaling pathway; failure to express either the functional receptor or ligand leads to a dysregulated immune system resulting in systemic autoimmunity. Based on the linkage between the lpr locus and Fas Ag expression, we propose that the failure of lpr mice to express Fas results in overproduction of Fas-ligand, whereas gld mice fail to make either the Fas-ligand or a functionally related protein, presumably belonging to the TNF family.

Animals↗
PubMed1993

Mature CD4+ T lymphocytes from MRL/lpr mice are resistant to receptor-mediated tolerance and apoptosis.

The goal of this study was to examine the functional responses and tolerance susceptibility of T lymphocytes from mice of the autoimmune strain, MRL/lpr. A population of autoreactive CD4+ T cells can be readily expanded from the lymphoid tissues of young lpr mice. Lines of IL-2-producing autoreactive and alloreactive lpr and alloreactive +/+ T cells were developed to study their responses to tolerance-inducing stimuli. Culture of +/+ T cells with high concentrations of immobilized anti-CD3 antibody induces both functional anergy and apoptosis. By contrast, lpr-derived T cell lines are relatively resistant to anergy and apoptosis. The implications of these findings for the development of autoimmunity, and the possible role of the Fas Ag in determining resistance or susceptibility to tolerance, are discussed.

Animals↗
PubMed1990

Development and characterization of monoclonal antibodies to a specific domain of human estrogen receptor.

We have synthesized three peptides with amino acid sequences identical to those spanning amino acids 201-215, 231-245, and 247-261 of the human estrogen receptor (hER). These peptides were conjugated to keyhole limpet hemocyanin and used as immunogens to develop monoclonal antibodies (MoAbs) to hER. Antibody responses were only elicited by the peptide with amino acid sequence 247-261. Splenocytes from immunized mice were used for hybridoma production. Of the seven MoAbs that recognized the native (functional) form of the ER, four (MoAbs 16, 33, 114, and 213) recognized the ER with high affinity, as demonstrated by the increased sedimentation coefficient of the antibody-complexed ER in sucrose density gradients. Antibodies 318, 35, and 36 bound to ER with low affinity since they immunoprecipitated ER, but the ER-antibody complex appeared to dissociate on sucrose density gradients. The high-affinity MoAbs appear to be site-specific since the peptide competed effectively for binding of the receptor by the antibody. The fact that they reacted with ER from human breast cancer and calf, rat, and mouse uterine tissues suggests that this epitope of the receptor is conserved in these species. Although the DNA-binding region appears to be conserved among the various steroid receptors, these MoAbs did not recognize the native forms of progesterone, androgen, or glucocorticoid receptors. These MoAbs bound to the KCl-activated 4S ER and heat-transformed 5S ER, suggesting that the antibody-binding site is accessible in the monomeric and dimeric forms of ER. The antibodies did not recognize the untransformed 8S ER in the presence of molybdate and without KCl, suggesting that the antibody-binding site in the oligomeric form of ER is inaccessible. The fact that the antibodies did bind to the unoccupied 4S ER was demonstrated by the data obtained with sucrose density gradient analysis followed by postlabeling of ER with [3H]estradiol. The antibodies bound to ERs with high affinity (KD = 0.4 to 1.8 nM). At a fixed concentration of antibody, ERs ranging from 20 to 1,000 fmol were detectable. These MoAbs did not inhibit nuclear or DNA binding of ER in vitro. This can be attributed to the dissociation of the antibodies from ER when the latter interacts with its acceptor site. These results demonstrate the development of site-specific MoAbs to the native form of the hER using synthetic peptides as immunogens.

Amino Acid Sequence↗
PubMed1989

Monoclonal antibody to SER immune suppressor detects polymeric forms of haptoglobin.

A series of monoclonal antibodies has been developed which is directed to a serum immunosuppressive factor, known as suppressive E-receptor factor (SER). SER, purified from the body fluids of cancer patients, is a polymeric form of haptoglobin, which is 100-1,000 times more potent an immunosuppressor than normal plasma haptoglobin and is immunochemically analogous to the neonatal form. Unlike the neonatal haptoglobin found in cord blood, SER, however, does not contain bound-hemoglobin. One group of monoclonal antibodies described in this study detects the polymeric forms of haptoglobin (SER) under non-denaturing conditions, but fails to recognize SER under the denaturing conditions of SDS-PAGE. A second group of monoclonal antibodies reacts only with the alpha subunit of haptoglobin but not with the beta subunit; in contrast, the commercially prepared polyclonal antisera to haptoglobin react with both the alpha and beta subunit. The average level of SER in normal human plasma (n = 19) was 1.0 micrograms/ml, regardless of age or sex. Since macrophages appear to secrete SER but do not synthesize haptoglobin, SER may represent an oxidized form of plasma haptoglobin generated from macrophages activated during an inflammatory response. These studies suggest that SER may be a negative feed-back regulator of immune response produced by activated macrophages.

Adult↗