Biomedical subjects

T Lehner

Publications and source records attributed to T Lehner.

At least 55 records · Page 3Linked to original sources

PubMed1999

Immunopathogenesis of Behçet's disease.

A working hypothesis is postulated for the immunopathogenesis of Behçet's disease (BD). Microbial infection induced stress upregulates HSP65 and MICA gene product which stimulate gamma delta and alpha beta T cell receptor positive cells, to generate effector and suppressor T cells (fig. 1). These activated T cells, antibodies and neutrophils induce cytokines to modulate the immune response. The end result of these complex cellular and cytokine immune interactions in HLA-B51 or genetically related subjects is to induce pathological changes consistent with BD.

Behcet Syndrome↗

PubMed1998

Hereditary febrile seizures: phenotype and evidence for a chromosome 19p locus.

The occurrence of febrile seizures (FSs) in large autosomal dominant FS kindreds makes possible accurate delineation of the pure clinical phenotype of hereditary FS among secondary FS cases, and the identification of gene loci causing susceptibility to FS. Recently FS gene loci on chromosomes 8 and 19 were identified. We studied the phenotype of FS in four large families in which FS is an autosomal dominant trait. Among 30 affected secondary FS cases, mean age of onset was 16.3 months (range 4 to 36 months), sex ratio was equal, and 43% were complex (13 of 30). Among these 30 secondary FS cases, the mean number of FSs was 2.1, half had only a single FS, and none had afebrile seizures. Penetrance was 0.67, approximately the same as in our previous larger group of 40 multicase FS families (0.64). The occurrence of DPT encephalopathy in a sib of a patient with FS raises the possibility that these two etiologies are related. Linkage studies showed that one of the four families (Family 1) was linked to chromosome 19p markers, none of the families was linked to chromosome 8q markers, and the largest FS family (Kindred 6) was unlinked to either 19p or 8q markers, supporting the hypothesis of genetic heterogeneity for FS.

Chromosomes, Human, Pair 19↗

PubMed1998

beta-chemokines and neutralizing antibody titers correlate with sterilizing immunity generated in HIV-1 vaccinated macaques.

One of the obstacles to AIDS vaccine development is the variability of HIV-1 within individuals and within infected populations, enabling viral escape from highly specific vaccine induced immune responses. An understanding of the different immune mechanisms capable of inhibiting HIV infection may be of benefit in the eventual design of vaccines effective against HIV-1 variants. To study this we first compared the immune responses induced in Rhesus monkeys by using two different immunization strategies based on the same vaccine strain of HIV-1. We then utilized a chimeric simian/HIV that expressed the envelope of a dual tropic HIV-1 escape variant isolated from a later time point from the same patient from which the vaccine strain was isolated. Upon challenge, one vaccine group was completely protected from infection, whereas all of the other vaccinees and controls became infected. Protected macaques developed highest titers of heterologous neutralizing antibodies, and consistently elevated HIV-1-specific T helper responses. Furthermore, only protected animals had markedly increased concentrations of RANTES, macrophage inflammatory proteins 1alpha and 1beta produced by circulating CD8(+) T cells. These results suggest that vaccine strategies that induce multiple effector mechanisms in concert with beta-chemokines may be desired in the generation of protective immune responses by HIV-1 vaccines.

AIDS Vaccines↗

PubMed1998

Antibody-secreting cells specific for simian immunodeficiency virus antigens in lymphoid and mucosal tissues of immunized macaques.

OBJECTIVES: To examine whether the route of immunization affects the induction of antibody-secreting cells (ASC) in the circulation of macaques. The distribution of ASC in the rectal mucosa and lymphoid tissues following challenge with simian immunodeficiency virus (SIV) was investigated. DESIGN: Macaques were immunized with recombinant SIV gp120 and p27 antigens by the targeted iliac lymph node (TILN) route of immunization or the nasal and rectal route, augmented by intramuscular immunization [naso-rectal intramuscular (NRI)]. The macaques were challenged with live SIV by the rectal route and ASC were assayed in the circulation before and after SIV challenge, and in the tissues removed at post-mortem. METHODS: ASC were examined in the circulation by Elispot assay. Mononuclear cells were prepared from peripheral blood, iliac and axillary lymph nodes and spleen. Rectal tissue was treated by enzyme digestion to elute mononuclear cells. RESULTS: TILN and NRI immunization induced circulating IgA and IgG ASC to both gp120 and p27. Following rectal challenge with SIV, TILN macaques were protected from infection whereas NRI route-immunized and unimmunized controls became infected. IgA ASC to p27 were increased significantly in the iliac lymph nodes of the TILN immunized macaques compared with unimmunized controls (P < 0.05). Only IgA ASC were found in the rectal mucosa of the immunized protected macaques but both IgA and IgG ASC were detected in the unimmunized infected macaques. Overall the number of IgG ASC specific for p27 was significantly higher in the infected NRI and control macaques than in the protected macaques (P < 0.02). A progressive increase in IgG but not IgA ASC was detected in the peripheral blood mononuclear cells of the unimmunized infected macaques. CONCLUSIONS: The results suggest that cells secreting IgA antibodies to p27 in the iliac lymph nodes of the TILN immunized macaques correlate significantly with protection from infection. The unimmunized infected macaques showed a progressive increase in IgG ASC in the peripheral blood after SIV challenge; this was found in the iliac and axillary lymph nodes and also in the spleen, suggesting that it is an immune response to the SIV infection.

Administration, Intranasal↗

PubMed1998

Generation of CD8 suppressor factor and beta chemokines, induced by xenogeneic immunization, in the prevention of simian immunodeficiency virus infection in macaques.

Previous xenogeneic immunization experiments in rhesus macaques with simian immunodeficiency virus (SIV) grown in human CD4(+) T cells consistently elicited protection from challenge with live SIV. However, the mechanism of protection has not been established. We present evidence that xenogeneic immunization induced significant CD8 suppressor factor, RANTES (regulated upon activation, normal T cell expressed and secreted), macrophage inflammatory protein (MIP) 1alpha, and MIP-1beta (P < 0.001 - P < 0.02). The concentrations of these increased significantly in protected as compared with infected macaques (P < 0.001). Xenogeneic stimulation in vitro also up-regulated CD8 suppressor factors (SF; P < 0.001) and the beta chemokines which were neutralized by antibodies to the 3 beta chemokines. Recombinant human RANTES, MIP-1alpha and MIP-1beta which bind to simian CCR5, suppressed SIV replication in a dose-dependent manner, with RANTES being more effective than the other two chemokines. The results suggest that immunization with SIV grown in human CD4(+) T cells induces CD8-suppressor factor, RANTES, MIP-1alpha and MIP-1beta which may block CCR5 receptors and prevent the virus from binding and fusion to CD4(+) cells.

Animals↗

PubMed1998

Seroprevalence of human immunodeficiency virus type 1 and sexual behaviors in bisexual African-American and Hispanic men visiting a sexually transmitted disease clinic in New York City.

A cross-sectional human immunodeficiency virus type 1 (HIV-1) serosurvey was conducted between January 1988 and January 1993 at a New York City sexually transmitted disease clinic serving predominantly African-American and Hispanic patients. Overall, 14% (415/3,069) of participating men reported having sex with men; among these, only 52 (13%) were classified as "homosexual" (having had sex with men exclusively since 1978). Most men (87%) who reported having sex with other men also reported having sex with women. These included 147 (35%) "bisexuals" (sex with more than one man and at least one woman since 1978) and 216 (52%) "heterosexuals" (sex with women since 1978 and sexual contact with men before 1978 or only once thereafter). Although HIV-1 seroprevalence was highest among "homosexual" men (70%, 95% confidence interval (CI) 55-81), it was also high among "bisexual" men (35%, 95% CI 27-43) and "heterosexual" men (17%, 95% CI 13-23), and was lowest in men who reported having no male sex partners in their lifetime (9%, 95% CI 7-10). It is possible that transmission of HIV-1 from bisexual men to female sexual partners plays a greater role in heterosexual transmission than was previously recognized.

Adolescent↗

PubMed1998

Targeted lymph-node immunization with whole inactivated simian immunodeficiency virus (SIV) or envelope and core subunit antigen vaccines does not reliably protect rhesus macaques from vaginal challenge with SIVmac251.

OBJECTIVE: Sexual transmission of HIV is the most common route of HIV transmission throughout the world. To prevent sexually transmitted HIV infection, a vaccine is urgently needed. A previous report demonstrated the targeted immunization of the iliac lymph nodes with simian immunodeficiency virus (SIV) subunits protects rhesus macaques from rectal challenge with SIV. We sought to determine whether this immunization strategy could protect rhesus macaques from vaginal challenge with SIV. DESIGN: Macaques were immunized with either whole-killed SIV or envelope and core subunit antigen vaccines. Using three independent groups, with three macaques in each group, macaques were immunized by the targeted iliac lymph-node (TILN) route, injecting the vaccine close to the iliac lymph nodes that drain the genital tract. RESULTS: The TILN immunization procedure induced high-titer SIV-specific immunoglobulin (Ig) G antibodies in serum in all animals and anti-SIV IgG and IgA antibodies in the cervicovaginal secretions of most animals. After a series of three or four TILN immunizations, the animals were intravaginally challenged with SIVmac251. All animals became virus isolation-positive, except one animal immunized with SIV p27 and gp120. This animal was virus isolation-negative but SIV DNA proviral sequences were detected in peripheral blood mononuclear cells. CONCLUSIONS: In this series of studies, reliable protection from vaginal transmission of SIV was not achieved by the TILN immunization procedure.

Animals↗

PubMed1998

Experimental mucosal induction of uveitis with the 60-kDa heat shock protein-derived peptide 336-351.

Subcutaneous (s.c.) immunization of rats with the human 60-kDa heat shock protein (HSP)-derived peptide 336-351 induced clinical and/or histological uveitis in 80 % of rats. Subsequent experiments to prevent the development of uveitis by oral or nasal administration of the peptide have failed. Instead, uveitis was induced in 74.6 % of rats given the peptide orally (5 times), in 75 % given the peptide nasally (5 times) or 91.7 % of those administered the peptide by both routes (10 times). Histological examination showed that any one route of administration of the peptide elicited iridocyclitis in 42.2 % but loss of photoreceptors only in 4.9 % of rats. In contrast, sequential administrations of the peptide by a combined mucosal-s.c. route resulted in iridocyclitis in only 25 % but loss of photoreceptors in 40 % of animals. Examination of mRNA from CD4-enriched splenic cells by reverse transcription-PCR failed to yield significant differences in Th1 or Th2 cytokines. Treatment with monoclonal antibody (mAb) to CD4 yielded a dose-dependent decrease in uveitis from 82 % to 25 %. Similarly, treatment with IL-4 significantly decreased the development of uveitis from 68 % to 30.4 %. Conversely, treatment of the rats with mAb to CD8 greatly enhanced the onset of uveitis (from about 22 days in the controls to 11 days) and all the rats developed uveitis by day 24. Thus, CD4+ cells mediate, whereas CD8+ cells suppress the development of uveitis. We suggest that this novel experimental mucosal model of induction of uveitis by the human 60-kDa HSP-derived peptide 336-351, which is specific in stimulating T cell responses in Behcet's disease, is consistent with the oro-genital onset of this disease and the development of uveitis.

Administration, Intranasal↗

PubMed1998

Homing of mononuclear cells from iliac lymph nodes to the genital and rectal mucosa in non-human primates.

The route of immunization may affect the type of immunity that is induced. The objectives of this investigation were to establish in the non-human primate if the internal iliac lymph nodes (LN) function as an inductive site of immunity from which mononuclear cells home to the rectal and cervico-vaginal mucosa. Rhesus macaques were immunized with simian immunodeficiency virus (SIV) core antigen p27 in the proximity of the iliac lymph nodes, and compared with the intramuscular (i.m.) (deltoid or gluteal), and axillary LN routes of immunization. The macaques were then challenged rectally or vaginally by a particulate SIVp27 antigen which was applied to the mucosal surface. The tracking dye PKH26 was injected near the immunizing LN or i.m. site and a week later the mucosal and lymphoid tissues were examined at autopsy. Preferential homing of PKH26-labeled cells from the internal iliac LN to the rectal and vaginal mucosa was demonstrated by flow cytometry after targeted iliac LN (TILN) but not after intramuscular (deltoid) or axillary LN immunization. Homing of the subsets of cells revealed that labeled CD4, CD8 and B cells, as well as monocytes were found in the rectum, colon, vagina or cervix. The results of this investigation shows that the route of immunization may affect regional mucosal immunity. Furthermore, the internal iliac LN may function as an inductive immunological site from which CD4, CD8 and B cells may home preferentially to the rectal, cervical and vaginal mucosa, as well as to the related regional but not the unrelated distal LN.

Animals↗

PubMed1998

HSP-derived peptides inducing uveitis and IgG and IgA antibodies.

Heat shock protein (HSP) 65 kD-derived peptides, which specifically stimulate T cells from patients with Behçet's disease (BD), are capable of inducing uveitis in rats. Mycobacterial HSP 65 kD and BD-specific peptides were injected into Lewis rats and the development of uveitis was monitored clinically and histologically, and IgG and IgA antibodies were measured using an enzyme-linked immunosorbent assay (ELISA). Rats immunized with HSP peptides that developed uveitis showed significantly higher serum IgG antibody levels to peptide 311-326 (P < 0.05) and the corresponding homologous human peptide 336-351 (P < 0.01) than rats without uveitis. Significant increases in serum IgA antibodies in rats with uveitis were also observed in those immunized with peptides 111-125, 311-326 and 336-351 (P < 0.05). Rats injected with HSP 65 kD showed a rise in IgG antibody levels to peptides 111-125, 154-172 and 311-326 and to a lesser extent, a rise in IgA antibody level to peptide 311-326. HSP showed almost complete inhibition of binding of IgG antibodies to HSP 65 kD, but peptides 111-125, 154-172, 311-326 and 336-351 showed inhibition to a lesser extent in a competitive assay. These results suggest that increases in IgG and IgA antibody levels to specific peptides within HSP, develop in rats with uveitis. The T and B cell epitopes responsible for the development of ocular disease in rats immunized with HSP-derived peptides, appear to be similar or identical to those found in patients with the ocular type of BD.

Animals↗

PubMed1998

Characterization of a recombinant plant monoclonal secretory antibody and preventive immunotherapy in humans.

A functional comparison was made between a monoclonal secretory antibody generated in transgenic plants and its parent murine IgG antibody.The affinity constants of both antibodies for a Streptococcus mutans adhesion protein were similar. However the secretory antibody had a higher functional affinity due to its dimeric structure. In the human oral cavity, the secretory antibody survived for up to three days, compared with one day for the IgG antibody. The plant secretory antibody afforded specific protection in humans against oral streptococcal colonization for at least four months. We demonstrate that transgenic plants can be used to produce high affinity, monoclonal secretory antibodies that can prevent specific microbial colonization in humans. These findings could be extended to the immunotherapeutic prevention of other mucosal infections in humans and animals.

Administration, Topical↗

PubMed1998

Induction of Th2 cytokine expression for p27-specific IgA B cell responses after targeted lymph node immunization with simian immunodeficiency virus antigens in rhesus macaques.

To determine if there is an association between the isotype of simian immunodeficiency virus (SIV)-specific B cell responses and the profile of Th1 and Th2 cytokine expression, rhesus macaques were immunized with SIV antigens via the iliac lymph nodes, using a targeted lymph node (TLN) immunization procedure. When CD4+ T cells purified from antigen-stimulated peripheral blood mononuclear cells were analyzed, the levels of Th2 cytokine production were gradually increased after the second and third immunizations. However, interferon-gamma production did not change. Analysis of SIV-specific B cell responses revealed that the main isotype was IgG after the second and third immunizations. In addition, a peak of SIV-specific IgA B cell responses was noted following the third immunization. These findings suggest that the induction of Th2 type responses in TLN-immunized rhesus macaques reflects the sequence of initial induction of SIV-specific IgG-producing cells followed by IgA-secreting cells.

Animals↗

PubMed1998

Protective mucosal immunity elicited by targeted lymph node immunization with a subunit SIV envelope and core vaccine in macaques.

Prevention of sexually transmitted HIV infection was first investigated in non-human primates by mucosal immunization via the rectal, vaginal or male urethral route. This was compared with subcutaneous targeted iliac lymph node (TILN) and systemic intramuscular immunization in non-human primates. TILN immunization elicited the most consistent mucosal sIgA and IgG antibody response in the rectum, vagina, urine and seminal fluid, as well as in blood. Both mucosal and TILN immunization induced a specific CD4+ T cell proliferative response in the iliac lymph nodes which drain these mucosal surfaces, and in the splenic and circulating T cells. In the next experiment macaques were immunized by the TILN route with SIV gp120 and p27 in alum. Rectal mucosal challenge with SIVmac 32H J5 molecular clone (or cell-free virus) induced total protection in four out of seven macaques, compared with infection in 13 of 14 unimmunized macaques or immunized by other routes (p = 0.025). The remaining three macaques immunized by the TILN route showed either decrease in viral load (> 90%) or transient viraemia, indicating that all seven TILN immunized macaques showed total or partial protection of rectal transmission by SIV (p = 0.001). Protection was associated with significant increase in the iliac lymph nodes IgA antibody secreting cells to p27 (p < 0.02), CD8-suppressor factor inhibiting replication of SIV in CD4+ T cells (p < 0.01) and the chemokines RANTES and MIP-1 beta (p < 0.01). We suggest that administration of gp120 and p27 by the TILN route may elicit protective B and T cell immunity which can significantly prevent rectal transmission of SIV or HIV.

Animals↗

PubMed1997

Mucosal immunization with DNA-liposome complexes.

The mucosal surfaces represent the primary site for transmission of several viruses including HIV. To prevent mucosal transmission and dissemination to the regional lymph nodes, an effective HIV vaccine may need to stimulate immune responses at the genital and rectal mucosa. Optimal induction of mucosal immunity in general requires targeting antigens to the specialized antigen presenting cells of mucosal associated lymphoid tissues. The nasal mucosa may provide a simple, non-invasive route to deliver DNA encoding the introduced gene to stimulate mucosal immunity. As a first step to evaluate the feasibility of this approach, we have investigated as a model system, systemic and mucosal immune responses elicited to firefly luciferase generated by DNA immunization. Incorporating DNA into liposomes with cationic lipids enhanced luciferase expression in nasal tissue, and was associated with induction of a humoral response in serum and vaginal fluids and also a proliferative and cytotoxic T lymphocyte response in the spleen and iliac lymph nodes draining the genital and rectal mucosa.

AIDS Vaccines↗

PubMed1997

European contribution to the science, prevention and management of HIV infection.

The objectives of the European Commission Biomed AIDS Programme are to enable Europe to pool its intellectual and financial resources in the control, treatment and prevention of HIV infection and AIDS. In order to facilitate this aim the Commission has allocated 40 to 50 million ECU over the past 6 years for concerted action of the Biomed projects on AIDS by the countries of the European Union. This is only a small proportion of the real cost spent by the member countries on this epidemic.

AIDS Vaccines↗

PubMed1997

T-cell epitopes recognized within the 65,000 MW hsp in patients with IgA nephropathy.

IgA nephropathy (IgAN) is the commonest cause of glomerulonephritis and clinical exacerbation of IgAN is frequently associated with mucosal infection. T-cell receptor gamma delta (TCR gamma delta+) cells are increased in both the circulation and in renal biopsies of patients with progressive IgAN. We examined the hypothesis that specific peptides within the 65,000 MW heat-shock protein (hsp) might stimulate TCR gamma delta cells and play a part in the immunopathogenesis of IgAN. We studied T-cell proliferative responses stimulated by overlapping peptides derived from the sequence of mycobacterial 65,000 MW hsp. Three T-cell epitopes have been identified (peptides 51-65, 71-85 and 281-295). The three peptides have a synergistic effect and they stimulate significantly higher proliferation of T cells in patients with IgAN than in disease or healthy controls. This response was inhibited by monoclonal antibodies (mAb) to TCR gamma delta+ and human leucocyte antigen (HLA) class I, but not by mAb to HLA class II. The involvement of TCR gamma delta+ cells was confirmed by up-regulation of the proportion of TCR gamma delta+ cells when stimulated with the three specific peptides. We suggest that IgAN might be associated with mucosal infection by a variety of micro-organisms and that peptides within the microbial hsp cross-react with the homologous human hsp which may stimulate TCR gamma delta+ cells and play a part in the pathogenesis of IgAN.

Adult↗

PubMed1997

The relationship between colonization and haemagglutination inhibiting and B cell epitopes of Porphyromonas gingivalis.

Passive immunization with the monoclonal antibody 61BG1.3 selectively prevents colonization by Porphyromonas gingivalis in humans (Booth V, Ashley FP, Lehner T. Infect Immun 1996; 64:422-7). The protective MoAb recognizes the beta component of the RI protease of P. gingivalis which is formed by proteolytic processing of a polyprotein precursor termed PrpR1. This subunit is both a haemagglutinin and an antigen which is recognized by sera from patients with periodontitis. In this study the relationship was investigated between a colonization epitope which is recognized by the MoAb 61BG1.3, a haemagglutinating and B cell epitope which are recognized by sera from patients with periodontitis. B cell epitopes were mapped by Western blotting with a series of truncated recombinant polypeptides spanning the adhesion domain within residues 784-1130 of PrpR1 and by ELISA using a panel of synthetic peptides spanning the same sequence. The epitope which is recognized by the protective MoAb was mapped within residues 907-931 of PrpR1, while serum responses of patients were directed predominantly to the adjacent carboxy-terminal sequence within residues 934-1042. The haemagglutinating epitope was mapped to residues 1073-1112. In view of our previous findings that the MoAb 61BG1.3 prevents colonization of P. gingivalis in vivo and inhibits haemagglutination, these two epitopes may be in proximity in the native protein. Active or passive immunization strategies which target the protective or haemagglutinating epitopes of the adhesion domain of PrpR1 may provide a means of preventing infection with P. gingivalis.

Adult↗

PubMed1997

Characterization of the Porphyromonas gingivalis antigen recognized by a monoclonal antibody which prevents colonization by the organism.

Monoclonal antibody (MAb) 61BG1.3 prevented recolonization of deep pockets by Porphyromonas gingivalis in patients with periodontitis. The aim of this work was to identify the antigen recognized by the MAb. This was carried out by dose-dependent inhibition with materials extracted from P. gingivalis and assessed by a radioimmunoassay. A protease preparation and a capsular extract inhibited about 95% of the binding activity, whereas LPS or fimbriae had no effect. However, about 125 times greater concentration of the capsular than the protease material was needed to inhibit 50% of the antibody activity, suggesting that the MAb recognizes the protease preparation and that the capsular extract contained some protease. Western blotting of MAb 61BG1.3 with recombinant prpR1 protein expressed in Escherichia coli confirmed that MAb 61BG1.3 recognizes the haemagglutinating protease and mapped its epitope to residues 748-1130 of the beta component of the polyprotein. Three major bands of M(r) 45,000, 38,300 and 31,400 were detected in native whole cells of the virulent P. gingivalis strain W50 by Western blotting with MAb 61BG1.3. The MAb inhibited haemagglutination of human red blood cells by P. gingivalis or by a native protease extract. Blocking adhesion of P. gingivalis to the receptors on erythrocytes might be a mechanism by which the MAb inhibits recolonization by the microorganism.

Adhesins, Bacterial↗