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H Hengartner

Publications and source records attributed to H Hengartner.

At least 235 records · Page 13Linked to original sources
PubMed1989

Clonal deletion of self-reactive T cells in irradiation bone marrow chimeras and neonatally tolerant mice. Evidence for intercellular transfer of Mlsa.

Tolerance to Mlsa has been shown to be associated with clonal deletion of cells carrying TCR beta chain variable regions V beta 6 or V beta 8.1 in mice possessing I-E antigens. To evaluate the rules of tolerance induction to Mlsa we prepared irradiation bone marrow chimeras expressing Mlsa or Mlsb and I-E by different cell types. Deletion of V beta 6+, Mlsa-reactive T cells required the presence of Mlsa and I-E products either on bone marrow-derived cells or on irradiated recipient cells. Tolerance was induced when Mlsa and I-E were expressed by distinct cells of the chimera. Also neonatally tolerized mice exhibited depletion of V beta 6+ cells after injection of I-E- Mlsa spleen cells (DBA/1) into newborn I-E+ Mlsb mice (BALB/c x B10.G)F1. These results suggest that the product of the Mlsa locus is soluble and/or may be transferred from cell to cell and bound to I-E antigens. The chimera experiments also showed that tolerance to Mlsa is H-2 allele independent, i.e., is apparently unrestricted. Differentiation of chimeric (H-2d/Mlsa x H-2q/Mlsb)F1 stem cells in either an H-2d or an H-2q thymus revealed that tolerance assessed by absence of V beta 6+ T cells is not dependent on the thymically determined restriction specificity of T cells.

Animals↗
PubMed1989

Major histocompatibility complex-linked susceptibility or resistance to disease caused by a noncytopathic virus varies with the disease parameter evaluated.

The influence of major transplantation antigens on susceptibility to T cell-mediated disease caused by infection with the noncytopathic virus lymphocytic choriomeningitis virus (LCMV) was evaluated in B10 H-2-congenic mice. Susceptibility to early T cell-mediated liver cell destruction (day 7-9) and early mortality (before day 12) was H-2Dq linked and correlated directly with early (day 6-8) and high cytotoxic T cell activity. In contrast, susceptibility to become an LCMV carrier, inability to rapidly clear virus, or tendency to develop late hepatitis (day 14-17) was linked to Dk and correlated with absence of early cytotoxic T cell activity. Thus, H-2D-regulated T cell-immune responses controlling both virus spread and immunopathology may directly determine the type and severity of disease. The results illustrate that susceptibility to disease caused by one virus may be linked to distinct MHC alleles dependent upon the disease parameter studied.

Animals↗
PubMed1989

[Immunologic tolerance].

The thymus plays a major role in T-cell maturation. Non-mature, bone-marrow-derived T-lymphocytes differentiate in the thymus into functional helper and cytotoxic T-cells, which have undergone two types of selection events before they leave the thymus: The negative selection, that is the elimination of self-reactive T-cells, and the positive selection, which supports the survival of T-cells capable of recognizing foreign antigen together with self-major histocompatibility antigens. Induction of T-cell tolerance towards the self-antigen Mlsa as a model is mediated by the selective deletion of Mlsa-reactive T-cells in the cortical region of the thymus. This was demonstrated by histological and flow cytofluorometrical analysis with a T-cell receptor variable-region-specific monoclonal antibody.

Autoimmune Diseases↗
PubMed1989

Postnatal disappearance of self-reactive (V beta 6+) cells from the thymus of Mlsa mice. Implications for T cell development and autoimmunity.

The postnatal ontogeny of potentially autoreactive T cells has been studied in a model system where a particular TCR beta chain variable domain (V beta 6) is correlated with reactivity to a minor antigen encoded by the Mlsa locus. Although absent among mature (CD4+ or CD8+) T cells in adult mice expressing Mlsa, brightly staining V beta 6+ cells were readily detectable in the thymus of neonatal animals, reaching a maximum after 4 d and decreasing rapidly thereafter. These V beta 6+ thymocytes were predominantly of the CD4+ phenotype and were localized in the medulla of the developing thymus. Furthermore, the intensity of TCR expression by these CD4+ cells was significantly (twofold) reduced as compared with age-matched Mlsb controls. A rapid disappearance of CD4+V beta 6+ cells (and corresponding decrease in TCR density) could also be observed in the thymus of Mlsb mice that had been injected neonatally with Mlsa spleen cells. Taken together, these results raise the possibility that some autoreactive T cells may persist after birth and that TCR downregulation may occur as a physiological response to tolerogenic signals in vivo.

Animals↗
PubMed1989

Anti-viral protection and prevention of lymphocytic choriomeningitis or of the local footpad swelling reaction in mice by immunization with vaccinia-recombinant virus expressing LCMV-WE nucleoprotein or glycoprotein.

The viral antigen specificity of primary cytotoxic T cell responses (CTL) of H-2b, H-2k, H-2q, H-2s, H-2f and some H-2-recombinant mice against lymphocytic choriomeningitis virus (LCMV-WE isolate) as well as the specificity of some CTL clones and T cell lines was defined on target cells infected with vaccinia-recombinant virus expressing nucleoprotein (Np) or glycoprotein (Gp). Np was recognized together with H-2q (Dq), H-2d (DLd), H-2s and H-2b (Db). Gp specificity was restricted to H-2f and H-2b (Kb and Db); H-2k-restricted CTL anti-LCMV responses were neither Gp nor Np specific. The anti-viral protective immunity induced by vaccinia-Gp or vaccinia-Np recombinants was evaluated in mice. In vivo protection was T cell mediated by class I restricted Ly-2+ T cells; it correlated well with the CTL specificity defined in vitro. Some of the CTL-nonresponder H-2 allele plus Np or H-2 plus Gp combinations were, however, protected to variable and low degrees by vaccinia-recombinant viruses, indicating that anti-viral protection is a more sensitive readout for CTL activity than the in vitro assay. For example, B10.D2 H-2d mice generated measurable CTL responses only to Np; after immunization with a vaccinia-Np recombinant, LCMV titers were 10(4) times lower in spleens than in vaccinia-primed controls. Although vaccinia-Gp-immunized BALB/c mice revealed no CTL activity in vitro, they nevertheless had 10(2) times lower LCMV titers in spleens than controls. Anti-viral protection, particularly in low-responder combinations, was usually short-lived and diminished after 3 weeks. In a high-responder situation, protection was of a longer duration (greater than 8 weeks). Vaccination with vaccinia-Np or Gp recombinants protected mice against lethal T cell-mediated lymphocytic choriomeningitis induced by LCMV or prevented the local footpad swelling reaction; these in vivo effects were H-2 dependent and followed the identical roles established for CTL recognition in vitro.

Animals↗
PubMed1989

Detection of perforin and granzyme A mRNA in infiltrating cells during infection of mice with lymphocytic choriomeningitis virus.

The analysis of gene expression in cytotoxic T cells by in situ hybridization of serial liver and brain sections from mice infected with lymphocytic choriomeningitis virus (LCMV) and immunostaining with T cell marker- and virus-specific antibodies revealed a close histological association of infiltrating lymphocytes expressing the perforin and granzyme A genes with virally infected cells. Maximal frequency of perforin and granzyme A mRNA-containing cells on liver sections preceded by about 2 days maximal LCMV-specific cytotoxicity of the lymphoid liver infiltrating cells. These results are most consistent with an involvement of perforin and granzyme A in cell-mediated cytotoxicity in vivo.

Animals↗
PubMed1989

Major histocompatibility complex--dependent T cell epitopes of lymphocytic choriomeningitis virus nucleoprotein and their protective capacity against viral disease.

In mice the immune response to infection with lymphocytic choriomeningitis virus (LCMV), a member of the arenavirus family, is mainly based on the activity of cytotoxic T cells. The immunogenic epitopes of the viral nucleoprotein recognized by cytotoxic T cells in various inbred strains of mice were defined. These epitopes were located in H-2d and H-2q mice in the amino-terminal region and in H-2b mice in the carboxy-terminal region of the nucleoprotein. A detailed analysis with synthetic peptides allowed the definition of a common epitope of 9 amino acids in H-2d and H-2q mice and of about 15 amino acids in H-2b mice. These T cell epitopes were all recognized in association with H-2 D or L transplantation antigen. The protective capacity of recombinant vaccinia viruses expressing these epitopes was documented by assaying prevention of virus replication, protection against LCM and prevention of the local footpad swelling reaction. Thus, distinct T cell epitopes on the same internal viral protein mediate protection in a major histocompatibility complex-restricted manner.

Amino Acid Sequence↗
PubMed1989

T cell tolerance to Mlsa encoded antigens in T cell receptor V beta 8.1 chain transgenic mice.

To study T cell tolerance, transgenic mice were generated that expressed the Mlsa-reactive T cell receptor (TCR) beta chain V beta 8.1 (cDNA) under the control of the H-2Kb promoter/immunoglobulin heavy chain enhancer on approximately 90% of peripheral T cells. In transgenic mice bearing Mlsa, thymocytes expressing the TCR at a high density were deleted and the percentage of Thy 1.2+ lymph node cells was reduced. The CD4/CD8 ratio of mature T cells was reversed in Mlsa and Mlsb transgenic mice independent of the H-2. RNA analysis and immunofluorescence with TCR V beta-specific antibodies revealed that expression of endogenous TCR beta genes was suppressed. Both Mlsa and Mlsb TCR beta chain transgenic mice mounted a T-cell-dependent IgG response against viral antigens, whereas the capacity to generate alloreactive and virus-specific cytotoxic T cells was impaired in TCR beta chain transgenic Mlsa, but not in transgenic Mlsb mice.

Animals↗
PubMed1989

Antiviral T cell competence and restriction specificity of mixed allogeneic (P1 + P2----P1) irradiation chimeras.

Mixed irradiation bone marrow chimeras were prepared by reconstituting lethally irradiated C57BL/10 (B10) or B10.D2 mice with T cell-depleted bone marrow cells of B10 plus B10.D2 origin. These chimeras were healthy and survived well under conventional housing conditions and after experimental laboratory infections. Of a total of 17 chimeras tested, 2 died spontaneously or from the injected virus. Twelve of fifteen chimeras mounted a measurable cytotoxic T cell response to virus. Despite approximately equal percentages of B10 and B10.D2 lymphocytes in chimeras, cytotoxic T cell responses to vaccinia virus and lymphocytic choriomeningitis virus were mediated variably by either syngeneic or allogeneic donor lymphocytes; thus the H-2 type of effector T cells frequently did not correspond to the 50:50 distribution of spleen or peripheral blood lymphocytes. Cytotoxic responses were restricted exclusively to recipient H-2 type. All mixed chimeras examined were able to mount a good IgG response to vesicular stomatitis virus. These results confirm previous data suggesting that such mixed chimeras are healthy and immunocompetent and demonstrate strict recipient-determined restriction specificity of effector T cells; they also suggest that if T help is necessary for induction of virus-specific cytotoxic T cells, it does not require host-restricted interactions between helper T cells and precursor cytotoxic T cells.

Animals↗
PubMed1989

Cloning, analysis, and expression of murine perforin 1 cDNA, a component of cytolytic T-cell granules with homology to complement component C9.

The nucleotide sequence coding for the cytotoxic T-lymphocyte (CTL) protein perforin 1 (P1) has been determined and the corresponding protein sequence has been derived. Murine CTL cDNA libraries contained in the vector lambda gt11 were screened by using a monospecific antiserum to purified P1. Three recombinant phages were isolated and their cDNA inserts were sequenced. The derived protein sequence contains 554 amino acids and displays, as expected, considerable homology with certain functional domains in the complement components C9, C8 alpha, C8 beta, and C7. The identity of P1 cDNA clones was verified by prokaryotic expression and the reactivities of antisera produced to the expressed proteins. In addition, antisera were produced to two synthetic peptides located in the center and C-terminal portions of P1. All antisera reacted with purified P1. In Northern blot analyses, P1 cDNA probes recognized a 2.9-kilobase mRNA only in CTL. Perforin mRNA was found in all cloned CTL and in all mixed lymphocyte reactions that gave rise to cytotoxic cells. Perforin mRNA was also detected in virus-specific CTL that had been generated in vivo and isolated from liver tissue of mice infected with lymphocytic choriomeningitis virus. The cell-specific expression of perforin is consistent with its postulated role in cytolysis.

Amino Acid Sequence↗
PubMed1989

Ontogeny and selection of the T cell repertoire in transgenic mice.

T cell receptor (TCR) transgenic mice have contributed to many aspects in understanding T cell ontogeny and selection of the peripheral repertoire. We have generated beta and alphabeta TCR transgenic mice, that predominantly express receptor chain(s) specific for the lymphocytic choriomeningitis virus glycoprotein, presented with the class I MHC H-2Db. This beta chain uses Vbeta8.1 and therefore reactivity with a self protein known as Mls(a) may also be studied. The effects of a functional beta transgene on rearrangement of the endogenous beta locus, and the gammadelta T cell lineage has been examined. In addition, both the beta and alphagamma transgenic mice have been used to study either positive or negative selection of T cells. Many groups have generated TCR transgenic mice, and those results, along with data from our transgenic animals will be discussed in this review.

Animals↗
PubMed1989

Tolerance to Mlsa by clonal deletion of V beta 6+ T cells in bone marrow and thymus chimeras.

To evaluate the rules of tolerance induction to Mlsa we investigated maturation of T cells in irradiation bone marrow chimeras and thymus transplanted mice expressing the strongly stimulatory Mlsa or the nonstimulatory Mlsb in presence or absence of the permissive MHC class II IE molecule. As shown previously, deletion of V beta 6+, Mlsa reactive T cells required the presence of Mlsa and IE products either on donor cells or on recipient tissue. Additional experiments revealed that tolerance was induced when Mlsa and IE were expressed by distinct cells of the chimera. Similar observations were made in chimeras reconstituted with bone marrow stem cells of two different strains of mice. The presented data confirm earlier evidence that tolerance is induced by cooperation of Mlsa-expressing cells and IE+ Mlsb antigen-presenting cells (APCs). Preliminary results suggest that APCs presenting Mlsa during negative selection of V beta 6+ cells in the thymus are radiosensitive and derived from lymphohemopoietic stem cells.

Animals↗
PubMed1989

Fate of potentially self-reactive T cells in neonatal mice: analysis of V beta 6+ T cells in Mlsa mice.

FACS analysis of either CD4 or CD8 depleted thymocytes revealed, that in adult Mlsa mice among CD4+ or CD8+ subpopulation of mature T cells V beta 6+ cells were absent. In contrast neonatal Mlsa mice had CD4+ V beta 6+ cells that rapidly decreased after day 4. On thymus cryosections of neonatal DBA/2 (Mlsa) mice V beta 6+ cells were found both in the cortex and the medulla of the thymus, in addition V beta 6+ cells were also detected in lymph nodes. After day 7-8 V beta 6+ cells disappeared from the medulla and the periphery. In the adult thymus only dull staining V beta 6+ cells were present in the cortex. Comparison of the fluorescence intensities of V beta 6 staining thymocytes from neonatally with Mlsa spleen cells tolerized mice with that of untreated BALB/c controls showed a significant decrease in T cell receptor density. Neonatal V beta 6+ T cells could be shown to be autoreactive against Mlsa, this reactivity declined at about the same time when the stimulatory capacity of Mlsa was established and could be first shown on day 4.

Animals↗
PubMed1988

Positive selection of CD4+ thymocytes controlled by MHC class II gene products.

The mature T-cell antigen receptor repertoire is characterized by lack of reactivity to self-components as well as by preferential reactivity to foreign antigens in the context of polymorphic self-proteins encoded within the major histocompatibility complex. Whereas the former characteristic (referred to as negative selection or tolerance) is associated with intrathymic deletion of T cells expressing T-cell antigen receptor beta-chain variable (V beta) domains, which confer a preferential reactivity to self antigens, the existence of the latter (referred to as positive selection or MHC restriction) has so far only been inferred indirectly from functional studies. We show here that intrathymic deletion of V+beta 6 T cells (reactive with a self-antigen encoded by the Mlsa locus) is controlled by polymorphic MHC class II determinants. Furthermore, in mice lacking expression of Mlsa, the same class II MHC loci control the frequency of occurrence of V+beta 6 cells among mature CD4+ T lymphocytes. These data are direct evidence for positive selection by MHC determinants in the thymus in unmanipulated animals.

Animals↗
PubMed1988

Deletion of self-reactive T cells before entry into the thymus medulla.

The thymus is important in the differentiation of bone marrow-derived precursor cells into functional T cells; humoral factors, as well as physical interactions with nurse cells, dendritic cells and epithelial cells, are thought to be instrumental in this process. Thymic lymphocytes mature during their migration from the cortical to the medullary region of the thymus, when they undergo phenotypic changes that include the acquisitions of T-cell antigen receptors, hormone receptors and differentiation antigens. Cortical T cells are thus mostly CD4+CD8+, whereas medullary T cells are either CD4+CD8- or CD4-CD8+. During this period T cells are subjected to two types of repertoire selection: all T cells recognizing self-MHC with low affinity may be preferentially amplified (positive selection), and in a second step T cells with high-affinity receptors for self-MHC determinants plus self antigens are eliminated (negative selection). We have described two monoclonal antibodies specific for the V beta 6 gene segment of the alpha/beta heterodimeric T-cell antigen receptor and have shown that most CD4+/V beta 6+ T cell recognize the Mlsa antigenic determinant but not Mlsb; similar results have been reported for V beta 8.1 and Mlsa. In both situations, tolerance to Mlsa correlated in an MHC-dependent fashion with absence of V beta 6 or V beta 8.1 T-cell antigen receptor expressing T cells in the periphery. We show here by immunostaining of thymus cryosections and cytofluorometric analysis that V beta 6-expressing cortical T cells are present at high density in both Mlsa and Mlsb mice, but do not enter the medullary region of Mlsa animals.

Animals↗
PubMed1988

Structure and function of human perforin.

Perforin (P1) is a cytolytic protein with similarity to complement component C9. P1 has been described as a unique component of murine cytolytic T-cell and rat natural killer cell granules Previous studies indicated that human granules and P1 differed from murine granules and P1 in that they appeared to be cytolytically less active and lacked the haemolytic activity characteristic of P1. It has been suggested that P1, like C9, is under the control of the homologous restriction factor. Here we determine the primary structure of human P1, re-examine its functional properties, and address the question of homologous restriction.

Amino Acid Sequence↗