DNA vaccination using coexpression of cytokine genes with a bacterial gene encoding a 60-kDa heat shock protein

Coexpression of cytokine genes together with antigen-encoding genes in DNA vaccination vectors can increase humoral and cellular immune responses and may steer them in a Th1 or Th2 direction. In this study, the modulatory effect of interleukin (IL)-2, IL-4, and interferon (IFN)-gamma coexpressed with the 60-kDa heat shock protein (Hsp60) of Yersinia enterocolitica O:8 (Y-Hsp60) was studied. DNA vaccination with gamma-hsp60 evoked specific humoral and cellular immune responses as well as reduction of the splenic bacterial load upon challenge with Y. enterocolitica in a mouse infection model. Coexpression of IL-2 or IFN-gamma enhanced Y. enterocolitica-specific total IgG (P < 0.05) and IgG2a antibody responses. Coexpression of IFN-gamma also improved the proliferative T cell responses upon stimulation with Y-Hsp60. A reduction of the splenic bacterial load as compared with the plasmid encoding Y-Hsp60 only was found for the IFN-gamma coexpressing vector. Thus, coexpression of cytokine genes such as IFN-gamma in DNA vaccination vectors might improve immunity and help to overcome the side effects of standard adjuvants.

Monocyte inflammatory protein-1 alpha facilitates priming of CD8(+) T cell responses to exogenous viral antigen

Dendritic cells (DC) derived from bone marrow precursors of BALB/c or C57BL/6 mice in low-serum cultures supplemented with granulocyte macrophage colony stimulating factor and Flt(3) ligand were pulsed in vitro with hepatitis B surface antigen (HBsAg) particles. DC processed exogenous HBsAg and presented its MHC class I-binding epitopes to cytotoxic T lymphocytes (CTL). This specific and restricted interaction of DC with CTL stimulated release of IFN-gamma and macrophage inflammatory protein (MIP)-1 alpha from the responding CTL. MIP-1 alpha enhanced the survival of DC in vitro but did not induce proliferation. Furthermore, co-delivery of MIP-1 alpha facilitated CTL priming in vivo to exogenous HBsAg in low responder C57BL/6 (H-2(b)) mice: a single injection of a low dose of HBsAg particles (without further adjuvants) successfully primed K(b)-restricted CTL responses to HBsAg only when the exogenous antigen was co-delivered with 100 ng MIP-1 alpha. These in vitro and in vivo data point to an important role of MIP-1 alpha in the DC-dependent priming of CTL to exogenous viral antigens.

Immunoglobulin leakiness in scid mice with CD4(+) T-cell-induced chronic colitis

Inflammatory bowel disease in scid mice is initiated by transplantation of CD4(+) T-cells from immunocompetent syngenic donor mice. As the disease progresses, immunoglobulin (Ig)-containing cells appear in the gut lamina propria, suggesting that locally accumulating Ig may play a role in disease development. In the present work we have investigated the relationship between disease progression and patterns or levels of Ig isotypes in the feces of scid mice suffering from an ongoing colitis. The data clearly showed that the severity or progression of the disease did not influence the levels of IgA, IgG1, IgG2a, IgG2b, and IgG3, whereas the level of fecal IgM increased during the course of colitis. The presence of the serum protein alpha-1-antitrypsin in fecal extracts from diseased mice suggests that some of the fecal Ig has leaked through the inflamed epithelial membrane into the gut lumen. Finally, Ig-containing cells were observed in mesenteric lymph nodes and in the spleen, suggesting that the fecal Ig is produced both systemically and locally in the gut wall. In conclusion, the present results demonstrate that the level of IgM increases as colitis progresses. Also, the five remaining major Ig isotypes are increased in the gut lumen of scid mice with colitis, but the individual Ig types vary randomly during the course of the disease. Thus, it is unlikely that immunoglobulins are involved in the immunopathogenesis of this model of colitis.

MMPI-2 profiles of Colombian, Mexican, and Venezuelan university students

Performance of 82 Colombian, 87 Mexican, and 96 Venezuelan university students and adult community dwellers on Spanish translations of the Minnesota Multiphasic Personality Inventory-2 (MMPI-2) were compared. Findings suggest more comprehensive research is required on applications of the MMPI-2 in Latin America and greater consideration of the roles of culture and nationality.

Fibre content and cellularity of the bone marrow of the iliac crest, vertebral column and sternum in chronic myeloproliferative disorders

Heterogeneous content of fibres and haematopoesis within the bone marrow may affect diagnosis and staging in chronic myeloproliferative disorders (CMPDs). To evaluate their distribution, we conducted a post mortem histomorphometric study of 22 patients with CMPD in chronic phases. In bone marrow specimens from the anterior and posterior iliac crest (right and left of each), the sternum, the 7th thoracic and the 3rd lumbar vertebra, the argyrophil fibres were counted using the line intersection method and the cellular and fatty bone marrow using the point count method. Statistical analysis was performed by direct comparison of the sites. The distribution of fibres was almost homogeneous in the patients with low fibre content, revealing a random diversity in more advanced stages of marrow fibrosis. 1/22 patient had no fibre increase in one specimen of the iliac crest and overt myelofibrosis in the other sites. 1/22 patient had myelofibrosis in two sites of the iliac crest and no fibre increase in vertebral column and sternum. The bone marrow cellularity was almost homogeneously increased in all patients. Myelofibrosis proved to be a generalised process with heterogeneous grades of severity in different regions of the bone marrow in CMPDs. No topographical bias was found. In contrast to the homogeneous increase of the bone marrow cellularity the topographical heterogeneity of the fibre content may limit the representativity of single bone marrow biopsies in patients with CMPDs.

Regenerative capacity and the number of satellite cells in soleus muscles of normal and mdx mice

Satellite cells are potential myogenic cells that participate in repair and growth of muscle fibres. In this investigation, the change in the number of satellite cells following severe muscle damage was monitored in soleus muscle of age-matched mdx and C57Bl/10 mice. Satellite cells were identified immunohistochemically in the light microscope by their association with a recently described marker protein, M-cadherin, and their location between the muscle fibre's sarcolemma and the surrounding basal lamina. In cross-sections of untreated soleus muscle of C57Bl/10 mice at 11-14. 5 months of age, nuclei of M-cadherin positive satellite cells on average amounted to 3.4% of the total number of myonuclei. Surprisingly, significantly higher numbers of satellite cell nuclei, both in absolute numbers (mean 24+/-11 versus 40+/-11 satellite cells per section) and relative to the total number of myonuclei (5. 3%), were found in similarly aged animals in which severe muscle damage had been inflicted 3-6 months before. Cross-sectional area, muscle tissue area and myonuclei counts had recovered to control values. In untreated muscles of age-matched mdx mice satellite cell counts were not different (2.7% of myonuclei) from C57Bl/10 mice. However, regeneration showed marked deficits, as there was a loss of about 36% total cross-sectional area, about 48% total muscle fibre area and about 43% myonuclei per section compared to the untreated mdx muscles. Furthermore, the absolute number of satellite cells decreased from 20+/-11 to 12+/-8 per section. The relative number of satellite cell nuclei remained comparable to, but did not exceed, the undamaged muscles. The poor recovery of muscle and the missing post-regeneration rise in satellite cell numbers may indicate the reproductive limits of the satellite pool.

Efficient vaccination by intradermal or intramuscular inoculation of plasmid DNA expressing hepatitis B surface antigen under desmin promoter/enhancer control

The small surface antigen of the hepatitis B virus (HB5Ag) was cloned into expression plasmid pCI under either a viral (CMV) promoter;enhancer sequence control (plasmid pCI/S), or a human desmin promoter/enhancer sequence control (plasmid pDes/S). Cells of different species and tissue origin transiently transfected in vitro with pCI/S or pDes/S plasmid DNA expressed readily detectable amounts of HBsAg, either intracellularly (precipitated from cell lysates), or as secreted products (detectable in ELISA). When these plasmids were used in DNA vaccination, both efficiently primed humoral and/or cellular immune responses to HBsAg after a single injection in Balb/c mice. Intramuscular injection of a high dose of DNA (100 rig/mouse) of both plasmids primed MHC-I-restricted cytotoxic T lymphocyte (CTL) responses and Thi serum antibody responses (IgGlIgG2a ratio O.4C0.7) of comparable magnitude in all vaccinated mice. Intradermal injection of low doses of (particle-coated) DNA (1 microgm/mouse) of both plasmids with the gene gun primed Th2 serum antibody responses (IgGl/IgG2a ratio > 100) but no CTL responses. The data indicate that antigens can be efficiently expressed under viral or eukaryotic promoter/enhancer control for immunogenic in vivo presentation, but that the technique, dose and/or route of DNA injection have a decisive role in determining the type of immune response elicited.

Ongoing murine T1 or T2 immune responses to the hepatitis B surface antigen are excluded from the liver that expresses transgene-encoded hepatitis B surface antigen

Different protein- or DNA-based vaccination techniques are available that prime potent humoral and cellular, T1 or T2 immune responses to the hepatitis B surface Ag (HBsAg) in mice. T1 and T2 are immune responses with isotype profile indicating Th1 and Th2 immunoregulation. We tested whether HBsAg-specific immune responses can be established in transgenic mice that express HBsAg in the liver (HBs-tg mice) using either these different vaccination techniques or an adoptive transfer system. HBsAg-specific responses could not be primed in HBs-tg mice with the established, potent vaccine delivery techniques. In contrast, adoptive transfers of T1- and T2-type HBsAg-immune spleen cells into congenic HBs-tg hosts (that were not conditioned by pretreatment) suppressed HBsAg antigenemia and gave rise to HBsAg-specific serum Ab titers. The establishment of continuously rising anti-HBsAg serum Ab levels with alternative isotype profiles (reflecting T1 or T2 polarization) in transplanted HBs-tg hosts required donor CD4+ T cell-dependent restimulation of adoptively transferred immune cells by transgene-derived HBsAg. Injections of HBsAg-specific Abs into HBs-tg mice did not establish stable humoral immunity. The expanding T1 or T2 immune responses to HBsAg in HBs-tg hosts did not suppress transgene-directed HBsAg expression in the liver and did not induce liver injury. In addition to priming functional antiviral effector cells, the conditioning of the liver microenvironment to enable delivery of antiviral effector functions to this organ are therefore critical for effective antiviral defense. A major challenge in the development of a therapeutic vaccine against chronic hepatitis B or C virus infection is thus the efficient targeting of specifically induced immune effector specificities to the liver.

Association of plectin with Z-discs is a prerequisite for the formation of the intermyofibrillar desmin cytoskeleton

Plectin is a high-molecular mass protein (approximately 500 kd) that binds actin, intermediate filaments, and microtubules. Mutations of the plectin gene cause a generalized blistering skin disorder and muscular dystrophy. In adult muscle, plectin is colocalized with desmin at structures forming the intermyofibrillar scaffold and beneath the plasma membrane. To study the involvement of plectin in myofibrillogenesis, we analyzed the spatial and temporal expression patterns of plectin in cultured differentiating human skeletal muscle cells and its relationship to desmin intermediate filaments during this process. Northern and Western blot analyses demonstrated that at least two different plectin isoforms are expressed at all developmental stages from proliferating myoblasts to mature myotubes. Using immunocytochemistry, we show that the localization of plectin dramatically changes from a network-like distribution into a cross-striated distribution during maturation of myocytes. Double immunofluorescence experiments revealed that desmin and plectin are colocalized in premyofibrillar stages and in mature myotubes. Interestingly, plectin was often found to localize to the periphery of Z-discs during the actual alignment of neighboring myofibrils, and an obvious cross-striated plectin staining pattern was observed before desmin was localized in the Z-disc region. We conclude that the association of plectin with Z-discs is an early event in the lateral alignment of myofibrils that precedes the formation of the intermyofibrillar desmin cytoskeleton.

Alternative pathways for processing exogenous and endogenous antigens that can generate peptides for MHC class I-restricted presentation

The concept of distinct endogenous and exogenous pathways for generating peptides for MHC-I and MHC-II-restricted presentation to CD4+ or CD8+ T cells fits well with the bulk of experimental data. Nevertheless, evidence is emerging for alternative processing pathways that generate peptides for MHC-I-restricted presentation. Using a well characterized, particulate viral antigen of prominent medical importance (the hepatitis B surface antigen), we summarize our evidence that the efficient, endolysosomal processing of exogenous antigens can lead to peptide-loaded MHC-I molecules. In addition, we describe evidence for endolysosomal processing of mutant, stress protein-bound, endogenous antigens that liberate peptides binding to (and presented by) MHC-I molecules. The putative biological role of alternative processing of antigens generating cytotoxic T-lymphocyte-stimulating epitopes is discussed.

Priming MHC-I-restricted cytotoxic T lymphocyte responses to exogenous hepatitis B surface antigen is CD4+ T cell dependent

MHC-I (Ld)-restricted, S28-39-specific CTL responses are efficiently primed in H-2d BALB/c mice injected with low doses of native hepatitis B surface Ag (HBsAg) lipoprotein particles without adjuvants. Priming of this CTL response by exogenous HBsAg required CD4+ T cell "help" and IL-12: this CTL response could be neither induced in mice depleted of CD4+ T cells by in vivo Ab treatment, nor in (CD4+ T cell-competent or CD4+ T cell-depleted) IL-12-unresponsive STAT4-/- knockout BALB/c mice. Codelivery of oligonucleotides (ODN) with immunostimulating CpG sequences (ISS) with exogenous HBsAg reconstituted the CTL response to exogenous HBsAg in CD4+ T cell-depleted normal mice and in CD4+ T cell-competent and CD4+ T cell-depleted STAT4-/- BALB/c mice. Injection (by different routes) of "naked" pCI/S plasmid DNA encoding HBsAg into IL-12-responsive or -unresponsive BALB/c mice efficiently primed the MHC-I-restricted, HBsAg-specific CTL response. CTL priming was not detectable when CD4+ T cell-depleted animals were subjected to genetic immunization. In vivo priming of the well-characterized CD8+ CTL response to HBsAg in "high responder" BALB/c mice either by exogenous surface lipoprotein particles or by DNA vaccination is thus CD4+ T cell dependent. CTL priming by exogenous HBsAg, but not by genetic immunization, is IL-12 dependent. The dependence of CTL priming by exogenous HBsAg on CD4+ T cells can be overcome by codelivering ODN with ISS motifs, and this "adjuvants effect" operates efficiently in IL-12-unresponsive mice. The data characterize a feature of the adjuvant effect of ISS-containing ODN on CTL priming that may be of major interest for the design of CTL-stimulating vaccines with efficacy in immunodeficiency conditions.

Adjuvants that enhance priming of cytotoxic T cells to a Kb-restricted epitope processed from exogenous but not endogenous hepatitis B surface antigen

Intramuscular (i.m.) or s.c. injection of plasmid DNA encoding hepatitis B small surface antigen (HBsAg) primes potent MHC I-restricted cytotoxic T lymphocyte (CTL) responses in H-2(d) (BALB/c) and H-2(b) (C57BL/6) mice. In contrast, i.m. or s.c. injection of exogenous HBsAg particles without adjuvants primes CTL responses in 'high responder' H-2(d) but not 'low responder' H-2(b) mice. We have shown that processing of exogenous but not endogenous HBsAg generates the Kb-binding S208-215 peptide ILSPFLPL. This system allowed us to optimize conditions for stimulating murine CTL responses to exogenous antigen by identifying adjuvants that facilitate priming of Kb-restricted CTL by injecting recombinant HBsAg particles into 'low responder' H-2(b) mice. Synthetic oligodeoxynucleotides with immunostimulating sequences or the recombinant cytokine IL-12 efficiently enhanced priming of CTL to exogenous HBsAg. Hence, the adjuvanticity of DNA sequences that induce Th1 cytokines facilitate priming of MHC I-restricted T cell responses to exogenous antigen and are therefore of potential value in formulating vaccines designed to enhance CTL priming to exogenous antigen.

Malabsorption with progressive weight loss and multiple intestinal ulcers in a patient with T-cell lymphoma

We describe a 52-year-old woman who presented with severe diarrhea, nausea, intermittent abdominal pain and weight loss of 18 kg within ten months. Jejunal and duodenal ulcers were detected by endoscopy and multiple biopsies revealed villous atrophy of the jejunum. However, neither gliadin nor endomysium antibodies were detected and no clinical and histological improvement was achieved after gluten withdrawal. Despite strong clinical suspicion for intestinal lymphoma many unrevealing biopsies were done. The patient developed intermittent septic fever and diagnostic laparotomy revealed jejunal perforation. Partial jejunal resection was performed and histology confirmed the diagnosis of an intestinal T-cell lymphoma without celiac disease. Malabsorption and all intestinal ulcers disappeared during the course of chemotherapy (six cycles CHOP) and the patient recovered remarkably.

Tumour necrosis factor-alpha (TNF-alpha) transcription and translation in the CD4+ T cell-transplanted scid mouse model of colitis

The adoptive transfer of activated CD4+ alpha/beta T cell blasts from the spleens of immunocompetent C.B-17+/+ or BALB/cdm2 mice into C.B-17scid/scid (scid) mice induces a colitis in the scid recipient within 8 weeks, which progresses to severe disease within 16 weeks. T cells isolated from recipient colon show a Th1 cytokine phenotype. We have examined the relationship between the phenotype of the cellular infiltrate and the transcription and translation of the proinflammatory cytokine TNF-alpha. The techniques of double indirect immunohistology and in situ hybridization using digoxigenin-labelled riboprobes were used. The prominent myeloid cell infiltrate in diseased tissues comprised F4/80+, Mac-l+ macrophages, neutrophils, dendritic cells and activated macrophages. TNF-alpha transcription and translation were associated with activated macrophages in the lamina propria. Activated macrophages transcribing and translating TNF-alpha were clustered in areas of tissue destruction. Crypt epithelium of inflamed tissues transcribed TNF-alpha at a very early stage of the disease process, but translation of TNF-alpha protein could only be found in advanced epithelial dysplasia. This indicates differential post-transcriptional control of TNF-alpha in activated macrophages and the epithelium.

Truncated or chimeric endogenous protein antigens gain immunogenicity for B cells by stress protein-facilitated expression

Truncated variants of the SV40 large T antigen (T-Ag) with an intact N terminus are as efficiently expressed in eukaryotic transfectants as wild-type (wt) T-Ag. Coprecipitation of N-terminal T-Ag fragments with the constitutively expressed, cytosolic stress protein hsp73 suggests that this chaperone stabilized expression of the truncated T-Ag fragments. In contrast to T-Ag, the 163-residue N-terminal preS domain of the hepatitis B surface antigen (HBsAg) is difficult to express. When the preS domain is C-terminally fused to a hsp73-binding cytoplasmic T-Ag (cT-Ag) fragment its stable expression as a chimeric cT-preS protein is obtained. DNA-based vaccination with plasmid DNA encoding either wt or hsp-associated mutant T-Ag elicited potent MHC class I-restricted, T-Ag-specific T cell responses. In contrast, DNA vaccination with hsp73-binding (mutant or chimeric) T-Ag variants, but not with wt T-Ag elicited T-Ag-specific antibody responses. Furthermore, vaccination with cT-preS-encoding plasmid DNA induced antibodies binding to the preS domain of the large HBsAg. Hence, hsp73-bound endogenous antigens efficiently stimulate antibody responses. These findings may be relevant for tumor immunology and autoimmunity.

Purification and characterization of hepatitis B virus surface antigen particles produced in Drosophila Schneider-2 cells

The small surface antigen of hepatitis B virus (HBV) was produced in Drosophila melanogaster Schneider-2 (DS-2) cells transfected stably using an inducible Drosophila metallothionein promoter. Selected clonal DS-2 cell-lines expressed and secreted large quantities of HBsAg particles consisting exclusively of non-glycosylated 25 kDa proteins. HBsAg produced by DS-2 cells had physical and biochemical properties very similar to 22 nm particles derived from the human hepatoma cell-line PLC/PRF/5. DS-2 cell-derived HBsAg particles were purified near homogeneity by a strategy based on protein concentration, precipitation and ultracentrifugation. The resulting HBsAg product was < 98% pure. A single immunisation of BALB/c mice with both DS-2 and yeast-cell derived purified HBsAg particles without adjuvants elicited a substantial humoral antibody and class-I restricted cytotoxic T lymphocyte (CTL) response. Adsorption of HBsAg particles to aluminium hydroxide resulted in increased levels of HBsAg-specific antibodies. However, CTLs were not elicited by HBsAg/Alum combinations. Thus, stably transfected DS-2 cells provide a useful source for the production of HBV subviral particles for diagnostic and research purposes as well as for novel vaccine development.

Colitis-inducing potency of CD4+ T cells in immunodeficient, adoptive hosts depends on their state of activation, IL-12 responsiveness, and CD45RB surface phenotype

We studied the induction, severity and rate of progression of inflammatory bowel disease (IBD) induced in SCID mice by the adoptive transfer of low numbers of the following purified BALB/c CD4+ T cell subsets: 1) unfractionated, peripheral, small (resting), or large (activated) CD4+ T cells; 2) fractionated, peripheral, small, or large, CD45RBhigh or CD45RBlow CD4+ T cells; and 3) peripheral IL-12-unresponsive CD4+ T cells from STAT-4-deficient mice. The adoptive transfer into SCID host of comparable numbers of CD4+ T cells was used to assess the colitis-inducing potency of these subsets. Small CD45RBhigh CD4+ T lymphocytes and activated CD4+ T blasts induced early (6-12 wk posttransfer) and severe disease, while small resting and unfractionated CD4+ T cells or CD45RBlow T lymphocytes induced a late-onset disease 12-16 wk posttransfer. SCID mice transplanted with STAT-4-/- CD4+ T cells showed a late-onset IBD manifest > 20 wk posttransfer. In SCID mice with IBD transplanted with IL-12-responsive CD4+ T cells, the colonic lamina propria CD4+ T cells showed a mucosa-seeking memory/effector CD45RBlow Th1 phenotype abundantly producing IFN-gamma and TNF-alpha. In SCID mice transplanted with IL-12-unresponsive STAT-4-/- CD4+ T cells, the colonic lamina propria, mesenteric lymph node, and splenic CD4+ T cells produced very little IFN-gamma but abundant levels of TNF-alpha. The histopathologic appearance of colitis in all transplanted SCID mice was similar. These data indicate that CD45RBhigh and CD45RBlow, IL-12-responsive and IL-12-unresponsive CD4+ T lymphocytes and lymphoblasts have IBD-inducing potential though of varying potency.

DNA immunization confers systemic, but not mucosal, protection against enteroinvasive bacteria

Naked plasmid DNA (pRc/Y-hsp60) with a cytomegalovirus promoter and a sequence encoding Yersinia enterocolitica 60-kDa heat shock protein (Y-HSP60) was used for vaccination. After intramuscular injection of pRc/Y-hsp60, Y-hsp60 mRNA could be detected by reverse transcription-PCR in muscle, liver and spleen. A single immunization with pRc/Y-hsp60 induced significant Y-HSP60-specific T cell responses after 1 week. IFN-gamma production by spleen cells upon stimulation with Y-HSP60 was strictly dependent on the presence of CD4+ T cells, indicating the generation of a Th1 response upon DNA immunization. DNA immunization in addition induced strong Y-HSP60-specific IgG2a, weak IgG1, but not IgA antibodies. Immunization of BALB/c and C57BL/6 mice with pRc/Y-hsp60 conferred protection against disseminated Y. enterocolitica infection in spleen, but not at the site of mucosal entry, the Peyer's patches. Furthermore, pRc/Y-hsp60 vaccination did not induce cross-protection against related pathogens. Vaccination of beta2-microglobulin- and H2-I-Abeta-deficient mice was not protective, suggesting that both CD4+ and CD8+ T cells are required for protective immunity induced by DNA vaccination.

Enhancing the immunogenicity of exogenous hepatitis B surface antigen-based vaccines for MHC-I-restricted T cells

Vaccination with either exogenous hepatitis B surface antigen (HBsAg) lipoprotein particles without adjuvants, or plasmid DNA encoding secreted small HBsAg stimulate long-lasting, potent antibody responses in H-2d (BALB/c) and C57Bl/6 (H-2b) mice. Vaccination with exogenous HBsAg primes MHC-I restricted cytotoxic T lymphocyte (CTL) responses to HBsAg in H-2d but not H-2b mice, while DNA vaccination primes HBsAg-specific CTL responses in both mouse strains. We defined vaccination strategies that could elicit CTL responses to exogenous HBsAg in 'low responder' C57Bl/6 mice. We found that the bacterial plasmid DNA itself, synthetic oligodeoxynucleotides containing immunostimulating sequences, or recombinant Th1 cytokines (IL12, IFNgamma) efficiently support priming of CTL responses to exogenous HBsAg in 'low responder' H-2b mice, but have only minor effects on CTL priming in 'high responder' H-2d mice in the high dose range tested. These molecularly well defined adjuvants can thus efficiently support priming of anti-viral T cell responses under 'low responder' conditions.

Immunostimulatory CpG motifs trigger a T helper-1 immune response to human immunodeficiency virus type-1 (HIV-1) gp 160 envelope proteins

Bacterial DNA sequences containing unmethylated CpG motifs have recently been proposed to exhibit immunostimulatory effects on B-, T- and NK cells, leading to the induction of humoral and cell-mediated immune responses. In the present study we investigated the immunomodulatory effects of a CpG-containing oligodeoxynucleotide (CpG ODN) to the HIV-1 gp 160 envelope (Env) protein in the BALB/c mouse model. Priming and boosting of mice with gp 160 adsorbed to aluminium hydroxide (Alum) induced a typical T helper-2 (Th2)-dominated immune response with high titers of gp 160-specific immunoglobulin (Ig)G1 isotypes but a weak IgG2a response. Specifically re-stimulated splenocytes from these mice predominantly secreted interleukin (IL)-5 but only minute amounts of interferon-gamma (IFN-gamma) upon specific re-stimulation. In contrast, a boost immunisation of gp 160/Alum primed mice with a gp 160/Alum/CpG combination resulted in a seven times higher production of IgG2a antibodies, without affecting the titers of IgG1 isotypes. Furthermore, approximately 10-fold increased levels of IFN-gamma, but significantly reduced amounts of IL-5, were secreted from gp 160-restimulated splenic cells. A further greater than 30-fold increase in the levels of specific IgG2a responses and a substantially elevated secretion of IFN-gamma were observed when the mice received gp160/Alum/CpG combinations for priming and boost injections. Thus, CpG ODNs are useful as an adjuvant to induce a typical Th0/Th1 response to HIV gp 160 proteins. However, despite the induction of a more Th1-like immune response, gp 16O/Alum/CpG combinations were not sufficient to prime an Env-specific cytotoxic T-cell (CTL) response.

Similar as well as distinct MHC class I-binding peptides are generated by exogenous and endogenous processing of hepatitis B virus surface antigen

Murine MHC class I-restricted cytotoxic T lymphocyte (CTL) responses can be primed by exogenous as well as endogenous hepatitis B surface antigen (HBsAg). Immunodominant CTL-defined epitopes of this viral envelope protein are the Ld-binding 12-mer S28-39 peptide IPQSLDSWWTSL in H-2d mice, and the Kb-binding 8-mer S208-215 peptide ILSPFLPL in H-2b mice. We tested if CTL recognizing these epitopes can be primed in vivo by HBsAg delivered as either an exogenous antigen (native HBsAg lipoprotein particles), or an endogenous antigen (plasmid DNA encoding HBsAg). Primed T cells were restimulated in vitro prior to the cytotoxicity assay with cells presenting the H-2 class I-binding epitopes generated by either exogenous or endogenous processing of HBsAg. The data indicate that the Ld-binding peptide S28-39 is generated during exogenous as well as endogenous processing of HBsAg. In contrast, the Kb-binding peptide S208-215 is generated during exogenous but not endogenous processing of HBsAg. Hence, some but not all MHC class I-binding, immunogenic peptides are generated during endogenous and exogenous processing of HBsAg but there also exists a repertoire of immunogenic peptides of viral origin that is only revealed after exogenous processing of viral proteins.

Immunization of woodchucks with plasmids expressing woodchuck hepatitis virus (WHV) core antigen and surface antigen suppresses WHV infection

DNA vaccination can induce humoral and cellular immune response to viral antigens and confer protection to virus infection. In woodchucks, we tested the protective efficacy of immune response to woodchuck hepatitis core antigen (WHcAg) and surface antigen (WHsAg) of woodchuck hepatitis virus (WHV) elicited by DNA-based vaccination. Plasmids pWHcIm and pWHsIm containing WHV c- or pre-s2/s genes expressed WHcAg and WHsAg in transient transfection assays. Pilot experiments in mice revealed that a single intramuscular injection of 100 microgram of plasmid pWHcIm DNA induced an anti-WHcAg titer over 1:300 that was enhanced by boost injections. However, two injections of 100 microgram of pWHcIm did not induce detectable anti-WHcAg in woodchucks. With an increase in the dose to 1 mg of pWHcIm per injection, transient anti-WHcAg response and WHcAg-specific proliferation of peripheral mononuclear blood cells (PMBCs) appeared in woodchucks after repeated immunizations. Four woodchucks vaccinated with pWHcIm were challenged with 10(4) or 10(5) of the WHV 50% infective dose. They remained negative for markers of WHV replication (WHV DNA and WHsAg) in peripheral blood and developed anti-WHs in week 5 after challenge. In contrast, woodchucks not immunized or immunized with the control vector pcDNA3 developed acute WHV infection. Two woodchucks immunized with 1 mg of pWHsIm developed WHsAg-specific proliferative response of PBMCs but no measurable anti-WHsAg response. A rapid anti-WHsAg response developed during week 2 after virus challenge. Neither woodchuck developed any signs of WHV infection. These data indicate that DNA-based vaccination with WHcAg and WHsAg can elicit immunity to WHV infection.

Similar as well as distinct MHC class I-binding peptides are generated by exogenous and endogenous processing of hepatitis B virus surface antigen

Murine MHC class I-restricted cytotoxic T lymphocyte (CTL) responses can be primed by exogenous as well as endogenous hepatitis B surface antigen (HBsAg). Immunodominant CTL-defined epitopes of this viral envelope protein are the Ld-binding 12-mer S28-39 peptide IPQSLDSWWTSL in H-2d mice, and the Kb-binding 8-mer S208-215 peptide ILSPFLPL in H-2b mice. We tested if CTL recognizing these epitopes can be primed in vivo by HBsAg delivered as either an exogenous antigen (native HBsAg lipoprotein particles), or an endogenous antigen (plasmid DNA encoding HBsAg). Primed T cells were restimulated in vitro prior to the cytotoxicity assay with cells presenting the H-2 class I-binding epitopes generated by either exogenous or endogenous processing of HBsAg. The data indicate that the Ld-binding peptide S28-39 is generated during exogenous as well as endogenous processing of HBsAg. In contrast, the Kb-binding peptide S208-215 is generated during exogenous but not endogenous processing of HBsAg. Hence, some but not all MHC class I-binding, immunogenic peptides are generated during endogenous and exogenous processing of HBsAg but there also exists a repertoire of immunogenic peptides of viral origin that is only revealed after exogenous processing of viral proteins.

Proliferation and apoptosis of lamina propria CD4+ T cells from scid mice with inflammatory bowel disease

Scid mice transplanted with low numbers of syngeneic CD4+ T cells, develop a chronic and lethal inflammatory bowel disease (IBD) within 4-6 months. We have used in vivo 5-bromo2-deoxy-uridine (BrdU) labeling to assess the proliferation of lamina propria-derived CD4+ T cells in diseased scid mice. The hourly rate of renewal of colonic lamina propria CD4+ T cells in diseased mice was 7% compared with 1.5% in normal BALB/c control mice. Transplantation of scid mice with in vitro activated CD4+ T cells accelerated the disease onset and development in a cell dose-dependent fashion when compared with non-activated CD4+ T cells. In pulse-chase experiments it was shown that BrdU-labeled cells disappeared rapidly from the lamina propria of diseased mice. DNA analysis revealed that this was due to the presence of nearly four times as many apoptotic CD4+ T cells in diseased than in control mice. Further analyses showed that the apoptotic lamina propria CD4+ T cells were derived from cells having entered the cell cycle within the previous 8 h. These data clearly demonstrate that vigorous CD4+ T cell proliferation and death are involved throughout the course of IBD.