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Biomedical subjects

M M Eibl

Publications and source records attributed to M M Eibl.

At least 37 records · Page 2Linked to original sources
PubMed1998

Modulation of immunologic responses to HIV-1MN recombinant gp160 vaccine by dose and schedule of administration. National Institute of Allergy and Infectious Diseases AIDS Vaccine Evaluation Group.

The safety and immunogenicity of HIV-1MN recombinant gp160 (MN rgp160) vaccine in healthy, uninfected volunteers was tested in a double-blind study with a factorial design. By random assignment, 20 volunteers received three 200 micrograms doses of MN rgp160 and four volunteers received placebo at days 0, 28, and 168 or 0, 56, and 224. Of the 24 volunteers, 16 received 200 micrograms or 800 micrograms of MN rgp160 and two received placebo at day 532 (month 18). The vaccine was safe. It induced T cell memory measured by Th1 cytokine production and lymphocyte proliferation, and serum anti-MN rgp160 IgG (all subclasses) and IgA antibodies. Fifteen of 20 vaccinees developed neutralizing antibody. The regimen including immunizations on days 0, 28, and 168 followed by the 800 micrograms fourth dose was most immunogenic.

AIDS Vaccines↗
PubMed1998

Adjuvant/carrier activity of inactivated tick-borne encephalitis virus.

Virus-like or virus-derived particles have been reported to increase the immunogenicity of foreign antigens. In this study formaldehyde-inactivated tick-borne encephalitis virus (TBEV), a potent immunogen in humans, was tested for possible adjuvant/carrier function. The results of our study revealed that substantial antibody titers against very low doses of tetanus toxoid could be obtained when mice were immunized with the antigen covalently coupled to TBEV (using N-succinimidyl-3-(2-pyridyldithio)propionate, a heterobifunctional, cleavable crosslinker containing a disulfide bridge). In contrast, only moderate anti-tetanus toxoid titers were induced by immunizations with a simple mixture of low dose tetanus toxoid and TBEV or when the disulfide bridge of the crosslinker used to couple tetanus toxoid to TBEV was cleaved prior to immunization. The antibody response to TBEV, on the other hand, was not influenced by its linkage to tetanus toxoid. Comparable anti-TBEV titers were obtained following immunization of the animals with either the TBEV-tetanus toxoid conjugate or the mixture of tetanus toxoid and TBEV. Prior application of a TBEV vaccine did not change the antibody response against tetanus toxoid and thus carrier-induced epitopic suppression could be ruled out. The abovementioned adjuvant/carrier properties of TBEV might make it a suitable candidate for use in bi- or multivalent vaccines containing weak immunogens.

Adjuvants, Immunologic↗
PubMed1998

Vaccination against tick-borne encephalitis virus, a flavivirus, prevents disease but not infection, although viremia is undetectable.

By adoptive transfer of sera or immunoglobulin preparations, vaccine-induced protection against TBEV has been demonstrated to be mediated by antibodies to the surface protein of TBEV, glycoprotein E. Nevertheless, the mechanism of vaccine-induced protection against TBEV remains unclear. Protection by E antibodies without in vitro neutralization was shown by one group, whereas others found a correlation between protection in vivo and neutralization in vitro. Here, the authors confirm in a mouse model of tick-borne encephalitis (TBE) that immunization with the whole-killed virus vaccine protects mice against a subsequent challenge with a highly lethal dose of virus, i.e. 250 LD50 doses. Vaccine-induced immunity, however, is not completely neutralizing as demonstrated by the development of immune responses to a non-structural virus protein absent from the vaccine, yet expressed in the course of virus replication. Antibodies specific for the non-structural protein 1 (NS1) and cytotoxic T-cells could be detected after, but not prior to, virus challenge of vaccinated animals, establishing that protection by this highly effective vaccine is not equivalent with complete neutralization of the challenge virus.

Adoptive Transfer↗
PubMed1998

Mutation analysis by a non-radioactive single-strand conformation polymorphism assay in nine families with X-linked severe combined immunodeficiency (SCIDX1).

X-linked severe combined immunodeficiency (SCIDX1) is an inherited disease characterized by profound abnormalities of cell-mediated and humoral immunity. Patients with SCIDX1 have defects in the common cytokine receptor gamma chain gene (IL2RG) that encodes a shared, essential component of the receptors for interleukin-2 (IL-2), IL-4, IL-7, IL-9 and IL-15. We have characterized nine SCIDX1 families by using a DNA-based, non-radioactive screening method and DNA sequencing. Nine different mutations were found, scattered from exon 1 to exon 5 of the IL2RG gene. Two of these mutations have been previously identified in other unrelated patients; the other seven are novel mutations that differ from all of the 95 already reported in the IL2RG mutation data base. In addition to describing novel mutations in the IL2RG gene, this study shows that the knowledge of the genetic defect and the use of an efficient, non-radioactive, and rapid screening approach have important implications for prenatal and postnatal diagnosis, carrier female identification, and possibly prenatal therapy.

DNA Mutational Analysis↗
PubMed1998

Prospective, double-blind, placebo-controlled, multicentre study on the effect of high-dose, intravenous immunoglobulin in children and adolescents with severe bronchial asthma.

OBJECTIVE: In order to study the effect of high-dose, intravenous immunoglobulin (i.v.IG) in severe childhood asthma, we investigated 31 children and adolescents (15 girls, 16 boys) aged 9-22 years (median age of 14 years) suffering from severe bronchial asthma. METHODS: In a prospective, double-blind fashion, patients received either four doses of i.v.IG (1 g/kg body weight) or identical doses of intravenous human serum albumin. The first two doses were given on two consecutive days, followed by two further doses at 4 week intervals. RESULTS: There was no statistical difference in the actively treated group when compared with the placebo group in symptom-score, bronchial hyperreactivity or peak-flow-variability. There was a trend for fewer total days of upper respiratory tract infections and also symptom-scores in the i.v.IG group but these did not reach statistical significance. CONCLUSION: Our data indicate that treatment with i.v.IG in asthmatic children did not show a significant reduction in the incidence of upper respiratory tract infections, but the patients who did have upper respiratory infections in the i.v.IG-group appear to have less protracted infections. Severity and bronchial hyperreactivity do not seem to be affected by the treatment as performed in our study.

Adolescent↗
PubMed1998

Neutralizing antibodies protect against lethal flavivirus challenge but allow for the development of active humoral immunity to a nonstructural virus protein.

Antibody-mediated neutralization of viruses has been extensively studied in vitro, but the precise mechanisms that account for antibody-mediated protection against viral infection in vivo still remain largely uncharacterized. The two points under discussion are antibodies conferring sterilizing immunity by neutralizing the virus inoculum or protection against the development of disease without complete inhibition of virus replication. For tick-borne encephalitis virus (TBEV), a flavivirus, transfer of neutralizing antibodies specific for envelope glycoprotein E protected mice from subsequent TBEV challenge. Nevertheless, short-term, low-level virus replication was detected in these mice. Furthermore, mice that were exposed to replicating but not to inactivated virus while passively protected developed active immunity to TBEV rechallenge. Despite the priming of TBEV-specific cytotoxic T cells, adoptive transfer of serum but not of T cells conferred immunity upon naive recipient mice. These transferred sera were not neutralizing and were predominantly specific for NS1, a nonstructural TBEV protein which is expressed in and on infected cells and which is also secreted from these cells. Results of these experiments showed that despite passive protection by neutralizing antibodies, limited virus replication occurs, indicating protection from disease rather than sterilizing immunity. The protective immunity induced by replicating virus is surprisingly not T-cell mediated but is due to antibodies against a nonstructural virus protein absent from the virion.

Animals↗
PubMed1997

Inhibition of IL-10 protein synthesis induces major histocompatibility complex class II gene expression in class II-deficient patients.

Major histocompatibility complex (MHC) class II deficiency is an inherited autosomal recessive combined immunodeficiency, characterized by a lack of constitutive expression of the human leukocyte antigen (HLA) class II genes. The patients investigated in this study are histoidentical twin brothers with a new phenotype in MHC class II deficiency. Examination of HLA-D locus genes in their fractionated peripheral mononuclear cells (MNCs) revealed an unusual and uncoordinated mRNA pattern. Here we analyzed the distribution of pro- and anti-inflammatory cytokines expressed in these patients' adherent and nonadherent MNCs. We show that gene expression of IL-1 alpha, IL-1 beta, IL-6, granulocyte-colony-stimulating factor, and IL-10 was induced in both cell fractions, whereas increased mRNA levels of interferon-gamma and the inducible nitric oxide synthase were exclusively detected in the patients' nonadherent MNCs. As IL-10 is known to be able to downregulate transcription of MHC class II and expression of IL-10 in the patients' MNCs was increased, we investigated the regulatory function of this cytokine. Interestingly, inhibition of IL-10 protein synthesis with IL-10-specific antisense oligonucleotide DNA (IL-10-AS-ODN) induced HLA-D locus genes in these MHC class II-deficient patients. Exposure of the nonadherent cell fraction to IL-10-AS-ODN resulted in a profound induction of a previously absent DR beta 1 and DP alpha gene expression. HLA-DQ beta mRNA levels, however, were increased in both the adherent and the nonadherent MNC population. Albeit expression of HLA-D locus genes was inducible via inhibition of IL-10 translation, surface expression of HLA class II antigens on the patients' MNCs was essentially negative. The data presented support the concept of a coordinated network of pro- and anti-inflammatory cytokine regulation and this network obviously has a significant role in the cell-type-specific regulation of MHC class II expression.

Cells, Cultured↗
PubMed1997

Two novel mutations in the MHC class II transactivator CIITA in a second patient from MHC class II deficiency complementation group A.

Congenital MHC class II deficiency or bare lymphocyte syndrome (BLS; McKusick 209920) is caused by defects in trans-acting regulatory factors that control MHC class II expression and is therefore a disease of gene regulation. There are at least four complementation groups and the genetic and molecular dissection of this rare disease has contributed considerably to our current understanding of the molecular mechanisms governing MHC class II expression. Identification of the gene that is defective in BLS complementation group A, CIITA (MHC class II transactivator), has led to the discovery that CIITA acts as a master control factor of MHC class II expression. We have identified the CIITA mutations in a second patient from BLS group A. Two novel mutations abolish CIITA function, as shown by transfection experiments. Molecular analysis of these two novel mutations, together with the one described earlier in the first patient, is informative in terms of CIITA structure-function relationships.

Alleles↗
PubMed1997

Detection of tick-borne encephalitis virus by sample transfer, plaque assay and strand-specific reverse transcriptase polymerase chain reaction: what do we detect?

Experimental inoculation of mice provides a well characterized model for studying infection with tick-borne encephalitis virus (TBEV), a flavivirus pathogenic for humans. Conflicting data on the kinetics of viremia and the development of virus titers in the brain, however, were only recently shown to have resulted from the use of assay systems with different levels of sensitivity in the titration of TBEV, i.e. plaque assay or sample transfer into naive recipient mice. Theoretically, RT-PCR could extend further the detectability to antibody-neutralized virus and when undertaken strand-specifically discriminate active replication from the mere presence of TBEV. We have compared the conventional methods for detection of TBEV with a newly devised RT-PCR method. As expected, RT-PCR, in contrast to the infectivity assays, detected antibody-neutralized virus. Furthermore, the mere presence or active replication of the virus could be differentiated by strand-specific RT-PCR. Plaque assay and sample transfer, in contrast, both detected only infectious virus. However, whereas sample transfer provides higher sensitivity for detection of TBEV from solid organs, the plaque assay is less costly and considering animals welfare more convenient. Thus, the newly devised method may allow the resolution of unanswered questions, while both the traditional infectivity assays retain their benefits in certain situations.

Animals↗
PubMed1997

Antibodies protect mice against challenge with tick-borne encephalitis virus (TBEV)-infected macrophages.

TBEV is a flavivirus highly pathogenic for humans. By transfer of antibodies directed to the TBEV surface glycoprotein E into mice, immune protection against subsequent inoculation with free TBEV particles could be achieved. After natural TBEV infection via the skin, however, cells of the monocyte/macrophage lineage were recently demonstrated to represent an important source of local virus replication before viraemia occurs. Whether antibodies can protect against virus challenge when contracted in the form of infected cells, however, is still unclear. In the current study, TBEV antibodies protected mice against challenge with either free virus or TBEV-infected macrophages equally well. This observation may be of more general significance.

Animals↗
PubMed1997

Antigen presentation by common variable immunodeficiency (CVID) B cells and monocytes is unimpaired.

CVID is a primary immunodeficiency syndrome comprising a heterogeneous group of patients with hypogammaglobulinaemia and defective formation of specific antibodies. Previous studies demonstrated defective T cell responsiveness to antigen in a major subgroup of patients. In the present study we investigated the capacity of peripheral blood monocytes and Epstein-Barr virus (EBV)-transformed B cell lines from seven patients with CVID, including two patients expressing an extended MHC haplotype described to be associated with CVID, to present antigen (Tet. Tox.) to CD4+ antigen-specific T cell lines from healthy controls. The results presented show an unimpaired capacity of peripheral blood monocytes to present antigen in all patients studied. In addition, the present study demonstrates for the first time that CVID B cells function normally as antigen-presenting cells (APC). These findings indicate that expression of a certain MHC phenotype in CVID is not associated with a defect in the presentation of recall antigen by monocytes and B cells. Based on these studies, uptake, processing and re-expression of recall antigen in association with MHC class II molecules on the APC surface are functional and there is no indication for structural abnormalities of the MHC class II molecules expressed by the patients studied that could be essential for their function in antigen binding and presentation.

Antigen Presentation↗
PubMed1997

Defective integration of activating signals derived from the T cell receptor (TCR) and costimulatory molecules in both CD4+ and CD8+ T lymphocytes of common variable immunodeficiency (CVID) patients.

CVID is characterized by hypogammaglobulinaemia and impaired antibody production. Previous studies demonstrated defects at the T cell level. In the present study the response of purified CD4+ and CD8+ T lymphocytes to stimulation with anti-TCR monoclonal antibody (the first signal) in combination with anti-CD4 or anti-CD8, anti-CD2 and anti-CD28 MoAbs (the costimulatory signals) was investigated. Both CD4+ and CD8+ T cells from the patients showed significantly reduced IL-2 release following stimulation via TCR and costimulation via CD4 or CD8 and CD2, respectively. However, normal IL-2 production following TCR plus phorbol myristate acetate (PMA) costimulation and normal expression of an early activation marker, CD69, after TCR+CD28 stimulation indicated that TCR was able to transduce a signal. Furthermore, both IL-2 and IL-4 release were impaired in CD4+ lymphocytes following TCR+CD28 stimulation. In addition, stimulation via TCR+CD28 resulted in significantly decreased expression of CD40 ligand in the patients. These results suggest that the integration of activating signals derived from the TCR and costimulatory molecules is defective in CVID patients; the defect is not confined to costimulation via a single molecule, or restricted to cells producing Th1-type cytokines such as IL-2, and is expressed in both CD4+ and CD8+ T cell subsets.

CD28 Antigens↗
PubMed1997

Pre- and postexposure protection by passive immunoglobulin but no enhancement of infection with a flavivirus in a mouse model.

Antibody-dependent enhancement of flavivirus infection, which except for dengue virus is without clear proof in vivo, is still under debate. Recently, postexposure immunoglobulin prophylaxis against tick-borne encephalitis virus, a flavivirus, was claimed to possibly have worsened the outcome of infection due to antibody-dependent enhancement. In the present study, antibody-dependent enhancement and pre- or postexposure protection by passive administration of tick-borne encephalitis virus immunoglobulin were evaluated in a mouse model. Preexposure treatment with homologous murine or heterologous human immunoglobulin provided complete protection against lethal challenge with tick-borne encephalitis virus. For postexposure treatment with antibody, the degree of protection correlated with the amount of immunoglobulin administered and was inversely related to the time interval between infection and treatment. Indications of enhancement of infection would have been increased lethality or reduced mean survival time, but neither was observed under the conditions used in our experiments despite the broad range of immunoglobulin and virus challenge doses applied. In contrast to these in vivo results, antibody-dependent enhancement of tick-borne encephalitis virus infection of murine peritoneal macrophages was readily demonstrable in vitro. Thus, antibody-dependent enhancement of viral infection in vitro does not necessarily predict enhancement in vivo.

Animals↗
PubMed1997

T cell activity and cytokine production in X-linked agammaglobulinemia: implications for vaccination strategies.

In the 5 X-linked agammaglobulinemia (XLA) patients studied we show that memory T cells are present and that T lymphocytes proliferate normally to mitogens, monoclonal antibodies and, in particular, to recall antigens demonstrating normal in vivo T cell priming despite the absence of B cells. Furthermore, in vitro T cell activation in response to both T cell receptor-independent and T-cell receptor-dependent signals leads to a pattern of cytokine production characteristic of primed T cells and necessary for normal T cell function. These data are in good agreement with results obtained in gene-targeted mice and further support the concept that the absence of B cells does not impair induction of in vivo T cell memory and effector function which is generally considered to be of great importance in conferring protection against viral infections. Thus, while there is no risk of inducing infections in XLA patients by administering vaccines containing killed viruses or recombinant viral proteins, stimulation of T cell immunity by such vaccines may be of potential benefit particularly in the defense against infections with viruses such as the hepatitis B virus to which hypogammaglobulinemic patients are particularly exposed.

Adolescent↗
PubMed1997

Detection of phosphatidylinositol glycan class A gene transcripts by RT in situ PCR hybridization. A comparative study using fluorescein, Texas Red, and digoxigenin-11 dUTP for color detection.

Gene-specific probes labeled with fluorescein, Texas Red, and digoxigenin-11 dUTP (DIG) were used for RT in situ PCR hybridization to detect PIG-A gene (phosphatidylinositol glycan class A) transcripts. The PIG-A gene is responsible for biosynthesis of the glycosylphosphatidyl-inositol (GPI) anchor. Lack of GPI anchor expression due to mutations can cause an acquired clonal hematologic disorder called paroxysmal nocturnal hemoglobinuria (PNH). In this RT in situ PCR study, two types of labeling methods, a direct method (using fluorescein and Texas Red) and an indirect method (using DIG-11 dUTP) were compared. Both were successfully applied to detect and localize the PIG-A gene transcripts within single cells of the cell lines AA2, H9, and JY. Furthermore, similar results for sensitivity and reproducibility were obtained. Advantages and disadvantages of the different labeling techniques are discussed. In addition, peripheral blood mononuclear cells from PNH patients were also included in this study.

Cells, Cultured↗
PubMed1996

Nitric oxide and viral infection: NO antiviral activity against a flavivirus in vitro, and evidence for contribution to pathogenesis in experimental infection in vivo.

Upon stimulation murine macrophages produce high levels of nitric oxide (NO), a potent microbicidal and tumoricidal agent recently also implicated as a mediator of antiviral defense. As dysregulated production of NO may lead to extensive tissue damage, the production of this powerful mediator is tightly regulated. Viral infection, however, may alter the regulation of certain macrophage functions, and recent work from our group demonstrated that viral infection--via induction of interferon-alpha beta synthesis -- may either prime for or down-modulate NO production. In light of antiviral activities of NO, down-modulation of NO production in viral infection would seem contradictory to antiviral defense. As others, however, have provided evidence that NO production may contribute to pathogenesis of infection with several neurotropic viruses, the role of NO production was investigated in vitro and in vivo in murine macrophages and in BALB/c mice infected with tick-borne encephalitis virus (TBE-V), a flavivirus. Macrophages from TBE-V-infected mice, but not from control mice, spontaneously produced NO upon culture in vitro. In contrast to the inhibitory effect of NO on replication of several poxviruses and herpes simplex virus, high levels of NO production did not display an inhibitory influence on TBE-V replication in vitro. And finally, in vivo administration of a competitive inhibitor of NO production, aminoguanidine, to TBE-V-infected mice significantly increased their mean survival time. Our results thus demonstrate that the antiviral activity of NO in vitro may be confined to certain viruses, whereas others remain unaffected. Furthermore, we provide evidence that NO production may even contribute to pathogenesis of viral infection in vivo.

Animals↗