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H Pircher

Publications and source records attributed to H Pircher.

At least 91 records · Page 5Linked to original sources
PubMed1990

Viral escape by selection of cytotoxic T cell-resistant virus variants in vivo.

Viruses persist in an immune population, as in the case of influenza, or in an individual, as postulated for human immunodeficiency virus, when they are able to escape existent neutralizing antibody responses by changing their antigens. It is now shown that viruses can in principle escape the immunosurveillance of virus-specific cytotoxic T cells by mutations that alter the relevant T-cell epitope.

Amino Acid Sequence↗
PubMed1990

T cell receptor (TcR) beta chain transgenic mice: studies on allelic exclusion and on the TcR+ gamma/delta population.

To study allelic exclusion of TcR genes we analyzed two types (I and II) of TcR beta transgenic mice. T cells derived from both types of mice contained similar amounts of transgenic RNA transcripts; however, surface expression of the transgenic beta chain was drastically reduced in type II compared to type I. In type I transgenic mice, productive rearrangements and expression of endogenous TcR beta genes were suppressed whereas on T cells of type II mice, both transgenic and endogenous TcR beta chains were expressed on the surface of the same cell. These findings suggest that allelic exclusion of TcR genes in beta transgenic mice depends on amount and/or onset of transgene expression during thymic development. Furthermore, TcR gamma rearrangements and the population of TcR gamma/delta-bearing double-negative CD4-CD8- thymocytes were reduced fivefold in type I transgenic animals. However, the V gamma usage and the gamma/delta+ dendritic epidermal cell populations appeared normal. RNase protection analysis further revealed low levels of transgenic TcR beta chain transcripts in TcR+ gamma/delta CD4-CD8- thymocytes. These results suggest that the beta transgene only quantitatively influences the gamma/delta T cell compartment, and supports the independence of the gamma/delta population.

Alleles↗
PubMed1990

Specific deletion of the J-C delta locus in murine alpha/beta T cell clones and studies using transgenic mice.

A deletion event in the T cell receptor (TcR) delta locus has been characterized in a panel of mouse alpha/beta cytotoxic T lymphocyte (CTL) clones. Data presented here shows that J delta 1, J delta 2 and C delta are absent from functional CTL clones while a germ-line D delta 1 fragment is retained, thus suggesting a specific deletion of this region. We have investigated the possible significance of the J-C delta deletion by generating T cell lines from TcR alpha/beta transgenic mice. Unlike control T cell lines which included a T cell line derived from a beta transgenic mouse, the lines expressing the transgenic alpha/beta heterodimer have not deleted the C delta region. This strongly suggests that the J-C delta deletion event is not responsible for directing T cells to the alpha/beta lineage, but rather is involved in the rearrangement or transcriptional activity of the alpha locus. In addition, to ensure that the alpha/beta transgene does not have any inhibitory affects on the rearrangement of the delta loci in general, the gamma/delta expressing dendritic epithelial T cell (DETC) population was examined in TcR alpha/beta transgenic mice and alterations in this T cell subset were not found. This finding that normal gamma/delta DETC cells are present in alpha/beta transgenic mice, together with the data showing that the D delta 1 region remains in an unrearranged germ-line configuration in functional alpha/beta CTL, suggests that commitment to the alpha/beta or gamma/delta lineage is predetermined at a particular stage in early T cell ontogeny.

Animals↗
PubMed1989

Tolerance induction in double specific T-cell receptor transgenic mice varies with antigen.

The crucial role of the thymus in immunological tolerance has been demonstrated by establishing that T cells are positively selected to express a specificity for self major histocompatibility complex (MHC), and that those T cells bearing receptors potentially reactive to self antigen fragments, presumably presented by thymic MHC, are selected against. The precise mechanism by which tolerance is induced and the stage of T-cell development at which it occurs are not known. We have now studied T-cell tolerance in transgenic mice expressing a T-cell receptor with double specificities for lymphocytic choriomeningitis virus (LCMV)-H-2Db and for the mixed-lymphocyte stimulatory (MIsa) antigen. We report that alpha beta TCR transgenic mice tolerant to LCMV have drastically reduced numbers of CD4+CD8+ thymocytes and of peripheral T cells carrying the CD8 antigen. By contrast, tolerance to MIsa antigen in the same alpha beta TCR transgenic MIsa mice leads to deletion of only mature thymocytes and peripheral T cells and does not affect CD4+CD8+ thymocytes. Thus the same transgenic TCR-expressing T cells may be tolerized at different stages of their maturation and at different locations in the thymus depending on the antigen involved.

Animals↗
PubMed1989

T cell function and expression are dramatically altered in T cell receptor V gamma 1.1J gamma 4C gamma 4 transgenic mice.

We have characterized transgenic mice carrying a functional T cell receptor (TCR) C gamma 4 (V gamma 1.1J gamma 4C gamma 4) gene. Results indicate that active transcription of the C gamma 4 transgene can influence expression of the endogenous C gamma 4, C gamma 1 (V gamma 3-, V gamma 4-, V gamma 2-, or V gamma 5J gamma 1C gamma 1) and C gamma 2 (V gamma 1.2J gamma 2C gamma 2) genes, while the ultimate expression of other TCR delta, alpha, and beta chain genes, as well as the adult T cell response, are relatively unaltered. Cells expressing transgenic C gamma 4 and endogenous delta TCR transcripts can migrate to the skin as dendritic epithelial cells (DEC) even though C gamma 4 cells are rarely, if at all, found in the skin. Transgenic and control mice were compared at 2 weeks, 6-7 weeks, and older. At 2 weeks, the thymus of transgenic mice, particularly the medulla, was much larger than control. Moreover, peripheral lymphoid tissues of younger mice were markedly (as much as 100-fold) more immunoreactive (both Con A response and alloreactivity). These differences, although persistent, became smaller in older mice. The data suggest that transgene expression has a major effect on T cell development and reactivity.

Animals↗
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

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↗
PubMed1987

T cell receptor variable gene usage in a specific cytotoxic T cell response. Primary structure of the antigen-MHC receptor of four hapten-specific cytotoxic T cell clones.

The primary structure of the alpha and beta chains of the T cell antigen receptor in four cytotoxic T cell clones specific for N-iodoacetyl-sulfonic-naphthyl-ethylene-diamine (AED)-haptenated target cells displaying a particular class I MHC molecule has been determined. Two of the T cell clones, 8/10-2 and 5/10-20K, recognize AED-modified targets in association with H-2Kb, while the other two clones 5/10-20D and C9 react with AED-modified cells in the context of H-2Db. Comparison of the nucleotide sequences of both the alpha and beta chain cDNAs and their deduced protein sequences indicates that a specific variable gene segment was not used to recognize the hapten and/or class I gene products. Furthermore, there does not appear to be any conserved amino acid residues used in the AED-specific response other than the framework amino acids. However, when the two clones 8/10-2 and 5/10-20D were compared, a striking similarity was seen in the J segments. These two clones that recognize AED in the context of different MHC epitopes used identical J alpha (J alpha 810) and J beta (J beta 2.6) gene segments. C9, specific for AED-Db, shared identical V beta (V beta 6) and J beta gene segments (J beta 1.1) as those of a cytotoxic T cell that recognizes allogeneic targets expressing Db. These data indicate that a simple rule governing the usage of the variable regions of either the alpha or beta T cell receptor (TcR) genes in the recognition of antigen and MHC gene products cannot be formulated. However, subtle similarities can be detected in some situations between the primary structures of the TcR and the targets they recognize.

Base Sequence↗
PubMed1987

Characterization of virus-specific cytotoxic T cell clones from allogeneic bone marrow chimeras.

We established several H-2-restricted lymphocytic choriomeningitis virus (LCMV)-specific cytotoxic T cell clones from spleens of virus-primed C57BL/6 or C57BL/10 (H-2b) and B10.BR (H-2k) mice and from allogeneic C57BL/10----B10.BR and B10.BR----C57BL/10 bone marrow chimeras. Two T cell clones of H-2b origin and restricted to H-2b, 3 of H-2k origin and restricted to H-2k were compared with two clones each derived from the two types of chimeras. Their surface phenotype was found to be Lyt-2+, L3/T4- and KJ16-133+ (2 of 9). Clones from chimeras expressed bone marrow donor H-2 and are restricted to the recipient H-2. H-2k-restricted clones were all specific for Kk whereas all H-2b-restricted clones were specific for Db. These restriction specificities could be further defined by the blocking activity of various monoclonal anti-H-2 antibodies. Interestingly the anti-H-2Db antibodies blocked the restricted virus-specific killing activity of the clones derived B10.BR----C57BL/10 chimeras much more effectively than the activity of the clones derived from conventional H-2b mice. The various clones differed with respect to their fine specificity for LCMV strains. The 3 clones of conventional B10.BR origin only recognized LCMV-WE but not LCMV-Armstrong, Aggressive or Docile; H-2b-restricted conventional clones recognized target cells infected with all LCMV strains except LCMV-UBC-Docile; the T cell clones from the bone marrow chimeras recognized with one exception all LCMV strains tested.

Animals↗
PubMed1987

Molecular analysis of the antigen receptor of virus-specific cytotoxic T cells and identification of a new V alpha family.

We have determined the primary structure of the alpha/beta-antigen receptor of a lymphocytic choriomeningitis virus (LCMV)-specific cytotoxic T cell clone (P14). The beta chain of the T cell receptor is composed of V beta 8.1, D beta and J beta 2.4 gene segments while the alpha chain uses a member of the V alpha 2 family and J alpha TA31. Southern blot analysis of a panel of six other independent LCMV-specific cytotoxic T cell clones did not reveal any preferential usage of the V alpha 2 or V beta 8 gene families in the cytotoxic LCMV response. Additionally, we have isolated and sequenced cDNA clones derived from the non-functionally rearranged alpha allele of P14. This transcript is composed of a unique V alpha gene segment which belongs to a new V alpha gene family.

Amino Acid Sequence↗
PubMed1986

Effect of rabbit anti-asialo GM1 treatment in vivo or with anti-asialo GM1 plus complement in vitro on cytotoxic T cell activities.

The susceptibility of cytotoxic effector lymphocytes and their induction to in vivo or in vitro treatment with rabbit anti-neutral glycolipid ganglio-N-tetraosylceramide (anti-ASGM1) antiserum was investigated. Intravenous injection of anti-ASGM1 antiserum eliminated measurable natural killer (NK) cell activity in spleen cells of mice infected for 5 days with Vaccinia virus, or for 8 days with lymphocytic choriomeningitis virus (LCMV) if injected 24 hr prior to testing. In addition, this treatment lowered measurable virus-specific cytotoxic T cell activity by 60 to 95%. Virus-specific cytotoxic T cell and NK cell activity generated during a primary infection in vivo was also sensitive to treatment in vitro with anti-ASGM1 antiserum (1/300 to 1/600 dilution) plus rabbit complement at a dilution of 1/15 (20 to 50% cell death, more than 30-fold decrease of cytotoxic activity); in vitro treatment with rabbit complement alone often enhanced NK and cytotoxic T cell activity slightly. In vivo treatment with anti-ASGM1 before primary immunization decreased generation of primary CTL only if high doses of anti-ASGM1 antiserum were injected twice. Antiviral T cells generated during secondary stimulation in vitro and alloreactive cytotoxic T cells from a mixed lymphocyte culture were resistant to treatment in vitro with anti-ASGM1 plus complement at the end of the culture period. Treatment in vitro of in vivo-primed responder spleen cells with anti-ASGM1 plus complement before their addition to a secondary restimulation culture resulted in complete inhibition of a secondary antiviral cytotoxic T cell response. In vivo treatment with anti-ASGM1 24 hr before their spleen cells were harvested and restimulated in vitro significantly reduced the virus-specific T cell activity of mice that had been immunized with virus several weeks previously. A cloned T cell line exclusively exerting NK-like activity was resistant, and two cloned virus-specific cytotoxic T cell lines were susceptible to treatment with anti-ASGM1 plus complement in vitro. These results caution the general use of rabbit anti-ASGM1 as a marker to distinguish NK from CTL cells; they indicate a possible relationship between NK and CTL cells and suggest that in vitro culture of lymphocytes may alter or select the cell surface expression or availability of the ASGM1 marker(s).

Animals↗
PubMed1986

T cell-specific gamma genes in C57BL/10 mice. Sequence and expression of new constant and variable region genes.

The T cell-specific gamma genes in C57BL/10 (B10) mice have been analyzed. Based on the cDNA sequences of these genes from antigen-specific MHC-restricted cytotoxic T cells, we found that the repertoire of these genes is not as limited as previously postulated (8). T cells from the B10 mice express an identical copy of V gamma J gamma C gamma (V gamma 10.8A-JC gamma 10.5) transcript previously found in T cells of BALB/c mice. In addition, a potentially functional mRNA using V gamma 10.8B and newly identified J gamma and C gamma gene segments were found. The new J gamma C gamma (JC gamma 10.8) is located 5' to the inverted V gamma 10.8B in the germline DNA of both B10 and BALB/c mice. This new C gamma is only 77 and 66% homologous to the C gamma 10.5 at the nucleotide and deduced protein sequences, respectively, thus making it a potential isotype of the C gamma genes reported previously. The V gamma 5.7, J gamma 2.3 gene segments and pseudogene C gamma 7.5 found in the germline DNA of BALB/c mice are absent in B10 mice. The loss of this gamma chain pseudogene in the B10 mouse strain, and the retention of all potentially functional V gamma, J gamma, and C gamma genes with highly conserved coding sequences supports the importance of these genes.

Amino Acid Sequence↗
PubMed1986

A monoclonal antibody against altered LFA-1 induces proliferation and lymphokine release of cloned T cells.

A murine monoclonal antibody (I-17, IgM) has the following functional effects on murine long-term T cell clones: inhibition of cell-mediated lysis, induction of proliferation, release of lymphokines and change of the cell morphology. The determinant detected by I-17 is expressed on long-term T lines but not on thymocytes, lymph node cells and spleen cells. I-17 precipitated proteins with apparent molecular mass of 220 kDa, 170 kDa, 150 kDa and 100 kDa. Biochemical studies indicate that the determinant recognized by I-17 is tunicamycin sensitive and that I-17 binds to the alpha chain of the lymphocyte function-associated antigen (LFA-1).

Animals↗
PubMed1986

Astrocytes as antigen-presenting cells. Part II: Unlike H-2K-dependent cytotoxic T cells, H-2Ia-restricted T cells are only stimulated in the presence of interferon-gamma.

Various studies strongly suggest that astrocytes are potent immune-regulating cells. They can be activated to release prostaglandin E, interleukin-1- and interleukin-3-like factors. Cocultivation of antigen-specific T cell lines and astrocytes results in induction of Ia on astrocytes and antigen-specific proliferation of T cells. In the current study, astrocytes were found to be incapable of serving as stimulator cells when unprimed T lymphocytes were used as responders in syngeneic or allogeneic lymphocyte reactions. However, when interferon-gamma (IFN-gamma) was added, astrocytes became Ia positive and potent stimulators in both syngeneic or allogeneic lymphocyte responses. In the presence of IFN-gamma, astrocytes presented antigens to Ia-restricted T hybridoma cells; in contrast hapten was presented to Kb-restricted cytotoxic cloned T cells by astrocytes in the absence of IFN-gamma. Thus, cultured astrocytes do function directly as accessory cells in class I antigen-dependent T cell activation, whereas Ia induction by IFN-gamma is necessary to enable them to present antigen to class II antigen-restricted T cells.

Animals↗
PubMed1985

Inhibition of hapten-specific cytotoxic T cell recognition by monoclonal anti-hapten antibodies.

The T cell-mediated cytotoxic response against autologous cells modified with the sulfhydryl reagent I-AED (N-iodoacetyl-N'-(5-sulfonic-1-naphthyl) ethylene diamine) is hapten specific and H-2 restricted (Levy, R. B., Shearer, G. M., Richardson, J. C. and Henkart, P. A., J. Immunol. 1981. 127: 523). We have produced a monoclonal antibody (V-6-3, IgM) which binds to AED-modified cells and proteins. Competition experiments by free hapten indicated that the binding was AED specific. The effect of the mAb on AED-specific cytotoxic T cell recognition at the effector and induction stage has been examined. Anti-AED mAb inhibited the cell-mediated lysis of some but not all AED-specific, H-2b-restricted long-term cytotoxic T cell clones and of bulk-cultured C57BL/6 anti-AED-self effector cells. This blocking was not due to nonspecific agglutination of targets since lysis of AED-modified target cells by alloreactive effector cells was not affected by this mAb under comparable conditions. Furthermore anti-AED mAb specifically inhibited the antigen-induced proliferation of AED-specific long-term cytotoxic T cell clones and the generation of AED-specific cytotoxic effector cells in secondary cultures. This monoclonal anti-AED antibody bound to cells modified by the recently described aminoreactive reagent AED-NH2 (Takai, Y., Mizuochi, H., Fujiwava, H. and Hamaoka, T., J. Immunol. 1984. 132: 57); these same target cells were, however, not lysed by AED-SH-specific cytotoxic T cell clones.

Animals↗