The role of helper T cell products in mouse B cell differentiation and isotype regulation

A comparison of oral and parenteral routes for therapeutic vaccination with HSV-2 ISCOMs in mice; cytokine profiles, antibody responses and protection

It is likely that recurrent infections with HSV-2 (or HSV-1) are influenced by local levels of immunity at mucosal surfaces, when virus reactivated from the latent state is infecting mucosal epithelial cells. Increasing the levels of cellular and humoral immunity through immunisation and maintaining such increased levels, may reduce establishment and spread of reactivated virus at the local site, thereby ameliorating recurrent disease symptoms. The use of HSV-2 antigens incorporated into immunostimulating complexes (ISCOMs) for immunisation of mice previously infected with HSV-2 was investigated in the present study. Prophylactic administration of HSV-2 ISCOM vaccine to mice elicits local antibody detectable in nasal washings, serum antibody and the presence of cytokines IL-2, IFN-gamma and IL-4 in supernatants from spleen cell cultures stimulated in vitro with HSV-2 antigens. Use of the same vaccine in mice infected previously with HSV-2, results in increased levels of total and subclass serum ELISA antibody and also increased levels of serum neutralising antibody. Treatment of HSV-2 infected mice with the HSV-2 ISCOM vaccine also induces higher levels of the cytokines IL-2, IFN-gamma and IL-4, in in vitro stimulated spleen cell cultures. Challenge with a lethal dose of HSV-1 showed that mice previously infected with HSV-2 and subsequently given two doses of HSV-2 ISCOMs vaccine were protected.

Relationship between IgE positive cell numbers and serum total IgE levels in mice treated with trimellitic anhydride and dinitrochlorobenzene

Although increased total serum IgE levels have been suggested as being predictive parameters of airway hypersensitivity caused by low molecular weight chemicals, it is not yet clear what level of serum total IgE in chemically-treated animals would translate to potential risk of inducing an immediate type hypersensitivity in human beings. Quantitative determination of IgE-bearing positive cells induced by chemicals in the tissue, particularly in respiratory airway, could help to resolve this problem. In BALB/c mice, serum total IgE concentrations and tissue IgE-bearing positive cell numbers were investigated following topical exposure to the chemicals, trimellitic anhydride (TMA) and dinitrochlorobenzene (DNCB), known in human as a respiratory and dermal sensitizer, respectively. In groups of mice 8 and 10 weeks of age, there were less individual variations in 25% TMA-induced serum total IgE increase than in other groups of mice 6, 12 and 16 weeks of age. When chemical concentrations of 1, 2 and 3% DNCB and of 6.25, 12.5 and 25% TMA were studied, we observed that the increase in IgE was dose-dependent for both chemicals, r=0.96; P=0.03 for DNCB and r=0.99; P=0.002 for TMA. However, the increase in serum total IgE induced by TMA was at least twice that induced by DNCB and was associated with the numbers of IgE bearing cells in the tracheal lamina propria (r=0.67, P=0.0003). A respiratory hypersensitivity caused by TMA, but not by DNCB, may be partly due to the presence of immuno effector cells bearing IgE at their surface in airway microenvironments, and their presence might be related to the higher level of serum total IgE. The IgE bearing positive cells could, therefore, help to identify chemicals which have the potential risk of inducing an immediate type hypersensitivity in humans.

RANTES potentiates antigen-specific mucosal immune responses

RANTES is produced by lymphoid and epithelial cells of the mucosa in response to various external stimuli and is chemotactic for lymphocytes. The role of RANTES in adaptive mucosal immunity has not been studied. To better elucidate the role of this chemokine, we have characterized the effects of RANTES on mucosal and systemic immune responses to nasally coadministered OVA. RANTES enhanced Ag-specific serum Ab responses, inducing predominately anti-OVA IgG2a and IgG3 followed by IgG1 and IgG2b subclass Ab responses. RANTES also increased Ag-specific Ab titers in mucosal secretions and these Ab responses were associated with increased numbers of Ab-forming cells, derived from mucosal and systemic compartments. Splenic and mucosally derived CD4(+) T cells of RANTES-treated mice displayed higher Ag-specific proliferative responses and IFN-gamma, IL-2, IL-5, and IL-6 production than control groups receiving OVA alone. In vitro, RANTES up-regulated the expression of CD28, CD40 ligand, and IL-12R by Ag-activated primary T cells from DO11.10 (OVA-specific TCR-transgenic) mice and by resting T cells in a dose-dependent fashion. These studies suggest that RANTES can enhance mucosal and systemic humoral Ab responses through help provided by Th1- and select Th2-type cytokines as well as through the induction of costimulatory molecule and cytokine receptor expression on T lymphocytes. These effects could serve as a link between the initial innate signals of the host and the adaptive immune system.

CpG oligodeoxynucleotide vaccination suppresses IgE induction but may fail to down-regulate ongoing IgE responses in mice

Antigen-specific IgE plays an important role in the pathogenesis of allergic disorders. Immunostimulatory CpG motifs (CpG) in bacterial DNA or synthesized oligodeoxynucleotides (ODN) are gaining recognition as potential immunomodulators for switching on protectiveT(h)1-mediated immunity and preventing or potentially inhibiting T(h)2-dependent allergic responses. To date, allergic models used in CpG ODN studies have been established by immunization of mice with allergen in the presence of adjuvant. This, in addition to failure to assess specific IgE production in most of the studies, has limited understanding of the role of CpG ODN vaccination in allergic responses. Here, we examine the effects of synthesized CpG ODN on both developing and ongoing IgE responses in mice sensitized using a recombinant mosquito salivary antigen (rAed a 2) without adjuvant. Pretreatment of mice with CpG ODN mixed with rAed a 2 successfully inhibited subsequent induction of serum rAed a 2-specific IgE (but not IgG1) and antigen-induced IL-4 and IL-5 production in spleen cells. This was associated with an increase of serum IgG2a and IL-12, and increased IFN-gamma and IL-12 production by spleen cells. In this model, however, co-administration of CpG ODN with rAed a 2 to presensitized mice failed to down-regulate ongoing IgE responses despite significant up-regulation of serum IL-12 and specific IgG2a. Strikingly, a transient skin delayed-type hypersensitivity reaction occurred in CpG ODN-treated mice. These observations provide a new insight into the potential therapeutic application of CpG ODN to allergic disorders.

Bi-directional activation between human airway smooth muscle cells and T lymphocytes: role in induction of altered airway responsiveness

Because both T lymphocyte and airway smooth muscle (ASM) cell activation are events fundamentally implicated in the pathobiology of asthma, this study tested the hypothesis that cooperative intercellular signaling between activated T cells and ASM cells mediates proasthmatic changes in ASM responsiveness. Contrasting the lack of effect of resting human T cells, anti-CD3-activated T cells were found to adhere to the surface of naive human ASM cells, increase ASM CD25 cell surface expression, and induce increased constrictor responsiveness to acetylcholine and impaired relaxation responsiveness to isoproterenol in isolated rabbit ASM tissues. Comparably, exposure of resting T cells to ASM cells prestimulated with IgE immune complexes reciprocally elicited T cell adhesion to ASM cells and up-regulated T cell expression of CD25. Extended studies demonstrated that: 1) ASM cells express mRNAs and proteins for the cell adhesion molecules (CAMs)/costimulatory molecules, CD40, CD40L, CD80, CD86, ICAM-1 (CD54), and LFA-1 (CD11a/CD18); 2) apart from LFA-1, ASM cell surface expression of the latter molecules is up-regulated in the presence of activated T cells; and 3) pretreatment of ASM cells and tissues with mAbs directed either against CD11a or the combination of CD40 and CD86 completely abrogated both the activated T cell-induced changes in expression of the above CAMs/costimulatory molecules in ASM cells and altered ASM tissue responsiveness. Collectively, these observations identify the presence of bi-directional cross-talk between activated T cells and ASM cells that involves coligation of specific CAMs/costimulatory molecules, and this cooperative intercellular signaling mediates the induction of proasthmatic-like changes in ASM responsiveness.

Indirubin inhibits inflammatory reactions in delayed-type hypersensitivity

Polygonum tinctorium Lour. (P. tinctorium) is known to have the ability to suppress inflammation. We attempted to isolate the active compounds from P. tinctorium based on their inhibitory effects on the production of interferon-gamma, which is a well-known inflammatory cytokine. We thus isolated indirubin, an isomer of indigo. Indirubin exerted its inhibitory effects not only on interferon-gamma production by human myelomonocytic HBL-38 cells but also on interferon-gamma and interleukin-6 production by murine splenocytes with no influence on the proliferation of either cells. Because of its inhibitory activity on interferon-gamma production, we further investigated the effects of indirubin on 2,4, 6-trinitro-l-chlorobenzene (TNCB)-induced delayed-type hypersensitivity as a representative inflammatory reaction. When injected intraperitoneally, indirubin significantly inhibited the ear swelling of TNCB-elicited mice. The amount of interferon-gamma in the culture supernatants of elicited mouse lymphocytes was inhibited by indirubin treatment. These results suggest that indirubin is a compound with anti-inflammatory effects.

Induction of IL-4-dependent, anaphylactic-type and IL-4-independent, non-anaphylactic-type IgG1 antibodies is modulated by adjuvants

Adjuvants can modulate the levels of anaphylactic- and non-anaphylactic-type IgG1 antibodies produced in response to a particular antigen. Mice immunized with ovalbumin (OVA) in Al(OH)(3) gel (alum) produced mostly the anaphylactic type, irrespective of the s.c. or i.p. route used, and this antibody was not detectable in IL-4(-/-) mice. In contrast, when OVA was injected in complete Freund's adjuvant (CFA), it induced substantial amounts of non-anaphylactic-type IgG1 in both IL-4(+/+) and IL-4(-/-) mice, and some anaphylactic IgG1 antibody in IL-4(+/+) mice only. When IFN-gamma was neutralized by specific mAb in wild-type mice immunized with OVA in CFA, the anaphylactic-type IgG1 antibody increased reaching the same levels as in alum-injected mice. This result indicates that the induction of IFN-gamma by the immunization with CFA down-regulates the production of IL-4-dependent, anaphylactic-type IgG1. Despite their different effects on IgG1 antibody production, both adjuvants dramatically increased the production of IgG2a in IL-4-deprived mice and did not induce any detectable IgE in these mice.

Novel diversity in IL-4-mediated responses in resting human naive B cells versus germinal center/memory B cells

Recent studies have defined several phenotypic and molecular changes associated with the maturation of naive human B cells within the milieu of germinal centers. Although naive B cells serve as natural precursors to germinal center (GC)/memory (M) subpopulations, little is known about the physiological requirements for the survival of the naive B cell pool in the absence of cell-cell contact or Ag-mediated activation. Because IL-4 induces expression of several membrane receptors such as CD23 which are uniquely present on resting human naive B lymphocytes, we hypothesized that these cells might be intrinsically programmed to respond to IL-4 in the absence of cell division. Using buoyant density-dependent isolation and further enrichment by negative/positive selection of human naive and GC/M subpopulations, we characterized cytokine receptor moieties on these cells and analyzed their survival and growth in the presence of IL-4 or IL-10. Resting naive B cells expressed significantly higher IL-4 receptor alpha-chain on their cell surface than the combined GC/M subpopulation. The IL-10 receptor and the IL-2 receptor gammac chain were almost equally expressed on both subpopulations. When cultured in vitro, the addition of IL-4, but not IL-10, protected naive B cells from apoptosis in the absence of activation and growth. However, IL-4 exerted no such effect on resting GC/M B cells. These data support the hypothesis that IL-4 plays a pivotal role in the survival and maintenance of resting human naive B cells.

Gene therapy of chronic inflammatory disease

Immune mediated inflammation that culminates in severe tissue necrosis is the hallmark of diseases that result from an inappropriate response to antigen. The inflammatory response becomes chronic when antigen is non-limiting and persists until the reactive tissue is destroyed, or the environment is changed and exposure to antigen is eliminated. The purpose of this review is to: (1) briefly outline common features of immune related inflammatory diseases such as rheumatoid arthritis (RA), multiple sclerosis (MS), inflammatory bowel disease (IBD), and allergic asthma; (2) provide a rationale for the development of gene based drugs for these indications; and (3) describe current experimental results that support the usefulness of this approach for creating novel DNA based therapeutics.

The Leishmania infantum acidic ribosomal protein LiP2a induces a prominent humoral response in vivo and stimulates cell proliferation in vitro and interferon-gamma (IFN-gamma) production by murine splenocytes

The acidic ribosomal proteins of the protozoan parasite Leishmania infantum have been described as prominent antigens during both human and canine visceral leishmaniasis. In this study we present data showing that the intraperitoneal administration in BALB/c mice of the Leishmania LiP2a protein, in the absence of any added adjuvants, elicited a strong humoral response as an indication that the protein is a potent immunogen. Despite the evolutionary conservation of the acidic ribosomal proteins, the antibody response was found to be specific for the Leishmania protein. Another remarkable finding was the observation that the LiP2a protein stimulates the in vitro proliferation of splenocytes from either LiP2a-immunized or naive BALB/c mice. Since similar proliferative indices were observed in T cell-enriched cultures, it is likely that the LiP2a stimulating activity is due mainly to T lymphocyte expansion. Also, the stimulatory effect was demonstrated to be antigen-specific, since the proliferation was abrogated by the presence of anti-LiP2a antibodies. Interestingly, the LiP2a protein stimulated the production of substantial amounts of IFN-gamma in cultured splenocytes from LiP2a-immunized mice. Our data indicate therefore that the immunostimulatory properties shown by this antigen should be taken into account when developing therapeutic and prophylactic vaccines against leishmaniasis.

Cloning, expression and purification of recombinant cotton rat interleukin-5

The coding sequence of the hispid cotton rat (Sigmodon hispidus) interleukin-5 (IL-5) was isolated by a combination of reverse transcription (RT)-PCR and RACE protocols from concanavalin A stimulated spleen cells. The open reading frame of 399 bp encodes a polypeptide of 132 amino acids. Comparison with the rat, mouse, gerbil and human counterparts revealed 88, 88, 87 and 75% identity at the nucleotide level and 88, 90, 89 and 70% at the amino acid level, respectively. The entire coding sequence, minus the putative signal peptide sequence, was inserted into an inducible Escherichia coli expression vector. The recombinant protein possessed an expected molecular mass of 14kDa and was located in bacterial inclusion bodies. A purification scheme under reducing and denaturing conditions followed by subsequent successive dialysis steps led to the recovery of a recombinant dimeric cotton rat IL-5. The biological activity of the recombinant protein was demonstrated in a murine cell line proliferation assay. This activity was specifically inhibited by rat monoclonal antibodies directed against mouse IL-5. Together with specific antibodies that can be generated easily, cotton rat IL-5 constitutes a useful tool for extending the use of the cotton rat animal model in the study of various human pathogens.

Cytokine and cytokine receptor expression as a biological indicator of immune activation: important considerations in the development of in vitro model systems

Studies of the biological activity of T-lymphocytes in response to immune activation are often based on in vitro models using polyclonal activators such as anti-CD3 antibodies, pharmacological agents, like phorbol esters, and mitogens, like phytohemagglutinin. Activation of T-lymphocytes results in expression of cytokine receptors, production and secretion of cytokines, expression of cell surface activation markers, and cellular proliferation. This study reviews the most commonly used methods of in vitro activation by non-specific polyclonal activators on target populations of both isolated T-lymphocytes and mononuclear cells. The resultant biological activity was measured by expression of cell surface cytokine receptors, intracellular cytokine expression and quantitation of secreted cytokines. This study demonstrates the different results that can occur depending upon the nature of the population making up the responding cells, method of activation, and duration of culture. Special care must be taken when developing in vitro models of immune activation and interpreting the resultant biological activity. The results of the experiments reviewed here demonstrate the importance of measuring cytokine receptors and quantitating cytokine secretion in conjunction with identifying the cytokine-producing cells. Recent advances in flow cytometry technology permit analysis of all these parameters on a single platform.

IL-18 induction of IgE: dependence on CD4+ T cells, IL-4 and STAT6

Overproduction of immunoglobulin E (IgE) and T helper cell type 2 (TH2) cytokines, including interleukin 4 (IL-4), IL-5 and IL-13, can result in allergic disorders. Although it is known that IL-4 is critical to the polarization of naïve CD4+ T cells to a TH2 phenotype, both in vitro and in many in vivo systems, other factors that regulate in vivo IL-4 production and TH2 commitment are poorly understood. IL-18, an IL-1-like cytokine that requires cleavage with caspase-1 to become active, was found to increase IgE production in a CD4+ T cells-, IL-4- and STAT6-dependent fashion. IL-18 and T cell receptor-mediated stimulation could induce naïve CD4+ T cells to develop into IL-4-producing cells in vitro. Thus, caspase-1 and IL-18 may be critical in regulation of IgE production in vivo, providing a potential therapeutic target for allergic disorders.

Weaning induces an increase in the number of specific cytokine-secreting intestinal lymphocytes in mice

Intestinal immunity differs from systemic immunity in several aspects and is frequently studied separately. In this work we have analysed the frequency of mononuclear cells spontaneously secreting the cytokines IL-2, IL-4, IL-5, IL-6, IL-10, interferon gamma (IFN-gamma) and tumour necrosis factor (TNF-alpha), in Peyer's patches and lamina propria of small intestine in mice by enzyme linked immunosorbent spot (ELISPOT) during 1 month after weaning. We have found a high percentage of spontaneous Th(1)as well as Th(2)cytokine-secreting lymphocytes in both populations, Peyer's patches and lamina propria. An increase in the number of the lymphocytes secreting most of the studied cytokines, at 1 and 2 weeks after weaning, was also observed. These results suggest that the increase in the number of cytokine secreting lymphocytes may be one of the potential mechanisms involved in the development of the intestinal immune system at weaning.

High-risk corneal allografts are capable of stimulating complement dependent cytolytic antibodies

PURPOSE

To prospectively characterize serum antibody responses in high-risk corneal allografts.

METHODS

Orthotopic and heterotopic C3H (H-2k) corneas were transplanted to CB6F1 (H-2b/d) recipient mice. Individual serum samples were collected at days 7, 14, 21, and 28 from orthotopically and heterotopically grafted mice. Samples were tested for anti-C3H antibodies using an enzyme-linked immunosorbent assay (ELISA). Serum samples were also tested for the ability to lyse target cells in the presence of complement.

RESULTS

In high-risk donor-host combinations, 100% corneal allograft rejection occurs in the absence of IgG1 production. Both orthotopic and heterotopic corneal allografts induced cytolytic complement fixing antibody isotypes.

CONCLUSIONS

Allospecific corneal antibody may be involved in corneal graft rejection in high-risk donor-host combinations.

Analysis of soluble and cell surface factors regulating anti-DNA topoisomerase I autoantibody production demonstrates synergy between Th1 and Th2 autoreactive T cells

The cellular and subcellular events governing Ab production with specificity for self Ags are poorly understood. In this study we examined the role of cellular interactions and cytokines in regulating the production of anti-DNA topoisomerase I (topo I) Ab, a major autoantibody in patients with systemic sclerosis (SSc). Topo I-specific T cell clones derived from SSc subjects and healthy donors were cultured with autologous peripheral blood B cells. Anti-topo I Ab production was induced by five of seven topo I-specific T cell clones derived from SSc subjects, but by none of eight T cell clones generated from healthy controls. However, two of the T cell clones from healthy controls provided help to HLA-DR-matched SSc B cells to produce anti-topo I Ab. The analysis of cytokine mRNA expression revealed that the ability to promote anti-topo I autoantibody production was strictly correlated with IL-2 and IL-6 expression by the T cell clones. Kinetic studies showed that IL-2 was required throughout the culture period for maximal autoantibody production and that both MHC-TCR and CD40-CD40L interactions were essential during the early phase of the culture. IL-6 was important in the late phase. Th1 clones (producing IL-2, but no IL-6) and Th2 clones (producing IL-6, but no IL-2) synergically activated autologous B cells to produce anti-topo I Ab. These results indicate that T cell-dependent B cell activation resulting in anti-topo I autoantibody production requires a series of temporally defined cell contact and soluble stimuli.

In activated mast cells, IL-1 up-regulates the production of several Th2-related cytokines including IL-9

Mast cells can play detrimental roles in the pathophysiology and mortality observed in anaphylaxis and other Th2-dominated allergic diseases. In contrast, these cells contribute to protective host defense mechanisms against parasitic worm infections. After IgE/Ag activation, mast cells can produce multiple cytokines that may enhance allergic inflammations, while a similar panel of Th2-related cytokines may support immunological strategies against parasites. Here we report that in primary mouse bone marrow-derived mast cells activated by ionomycin or IgE/Ag, the proinflammatory mediator IL-1 (alpha or beta) up-regulated production of IL-3, IL-5, IL-6, and IL-9 as well as TNF, i.e., cytokines implicated in many inflammatory processes including those associated with allergies and helminthic infections. IL-1 did not induce significant cytokine release in the absence of ionomycin or IgE/Ag, suggesting that Ca-dependent signaling was required. IL-1-mediated enhancement of cytokine expression was confirmed at the mRNA level by Northern blot and/or RT-PCR analysis. Our study reveals a role for IL-1 in the up-regulation of multiple mast cell-derived cytokines. Moreover, we identify mast cells as a novel source of IL-9. These results are of particular importance in the light of recent reports that strongly support a central role of IL-9 in allergic lung inflammation and in host defense against worm infections.

Protective immunity to rotavirus shedding in the absence of interleukin-6: Th1 cells and immunoglobulin A develop normally

We investigated whether interleukin-6 (IL-6) was required for the development of immunoglobulin A (IgA)- and T-helper 1 (Th1)-associated protective immune responses to rotavirus by using adult IL-6-deficient mice [BALB/c and (C57BL/6 x O1a)F(2) backgrounds]. Naive IL-6(-) mice had normal frequencies of IgA plasma cells in the gastrointestinal tract. Consistent with this, total levels of IgA in fecal extracts, saliva, and sera were unaltered. In specific response to oral infection with rhesus rotavirus, IL-6(-) and IL-6(+) mice exhibited efficient Th1-type gamma interferon responses in Peyer's patches with high levels of serum IgG2a and intestinal IgA. Although there was an increase in Th2-type IL-4 in CD4(+) T cells from IL-6(-) mice following restimulation with rotavirus antigen in the presence of irradiated antigen-presenting cells, unfractionated Peyer's patch cells failed to produce a significant increase in IL-4. Moreover, virus-specific IgG1 in serum was not significantly increased in IL-6(-) mice in comparison with IL-6(+) mice. Following oral inoculation with murine rotavirus, IL-6(-) and IL-6(+) mice mediated clearance of rotavirus and mounted a strong IgA response. When IL-6(-) and IL-6(+) mice [(C57BL/6 x O1a)F(2) background] were orally inoculated with rhesus rotavirus and later challenged with murine rotavirus, all of the mice maintained high levels of IgA in feces and were protected against reinfection. Thus, IL-6 failed to provide unique functions in the development of IgA-secreting B cells and in the establishment of Th1-associated protective immunity against rotavirus infection in adult mice.

The adjuvant monophosphoryl lipid A increases the function of antigen-presenting cells

The induction of immune responses in vivo is typically performed with antigens administered in external adjuvants, like alum, complete Freund's adjuvant, LPS and, more recently, monophosphoryl lipid A (MPL). However, the role of the adjuvant is still poorly defined. The aim of this study was to test whether the MPL affects the function of antigen-presenting cells (APC) in vitro and in vivo. Antigen-pulsed APC [including macrophages, B cells and dendritic cells (DC)] were incubated or not with MPL, and their ability to sensitize naive T cells was tested in vitro and in vivo. The data show that MPL enhances the ability of macrophages and B cells to sensitize naive T cells, and confers to them the capacity to induce the development of T(h)1 and T(h)2. Administration of MPL i.v. in mice results in the redistribution of fully mature DC in the T cell area of the spleen. These observations suggest that MPL may induce an antigen-specific primary immune response by provoking the migration and maturation of DC that are the physiological adjuvant of the immune system.

CD134L engagement enhances human B cell Ig production: CD154/CD40, CD70/CD27, and CD134/CD134L interactions coordinately regulate T cell-dependent B cell responses

CD134 is a member of the TNFR family expressed on activated T cells, whose ligand, CD134L, is found preferentially on activated B cells. We have previously reported that the CD70/CD27 interaction may be more important in the induction of plasma cell differentiation after the expansion phase induced by the CD154/CD40 interaction has occurred. When CD134-transfected cells were added to PBMCs stimulated with pokeweed mitogen, IgG production was enhanced in a dose-dependent fashion. Addition of CD134-transfected cells to B cells stimulated with Staphylococcus aureus Cowan I strain/IL-2 resulted in little if any enhancement of B cell IgG production and proliferation. We found that while CD134-transfected cells induced no IgG production by themselves, it greatly enhanced IgG production in the presence of CD40 stimulation or T cell cytokines such as IL-4 and IL-10. The addition of CD134-transfected cells showed only a slight increase in the number of plasma cells compared with that in the culture without them, indicating that an increased Ig production rate per cell is responsible for the observed enhancing effect of CD134L engagement rather than increase in plasma cell generation. These results strongly suggest different and sequential roles of the TNF/TNFR family molecules in human T cell-dependent B cell responses through cell-cell contacts and the cytokine network.

The immunogenicity of single and combination DNA vaccines against tuberculosis

DNA immunization is a promising new approach for the development of novel tuberculosis vaccines. In this study, the immune responses following the administration of single and combination tuberculosis DNA vaccines were evaluated. Single DNA vaccines encoding the MPT-63 and MPT-83 tuberculosis antigens evoked partial protection against an aerogenic challenge with M. tuberculosis Erdman in the mouse model of pulmonary tuberculosis. Immunization with a multivalent combination DNA vaccine (containing the ESAT-6, MPT-64, MPT-63, and KatG constructs) generated immune responses that indicated an absence of antigenic competition since antigen-specific cell-mediated and humoral responses were detected to each component of the mixture. More importantly, the combination vaccine elicited a strong protective response relative to the protection evoked by live BCG vaccine.

Seasonal variations in cytokine expression and cell-mediated immunity in male rhesus monkeys

Our objectives in this study were to examine seasonal changes in immune responses including cytokine profiles of male rhesus monkeys housed under natural lighting conditions. We also monitored circannual changes in the secretion of several immunomodulatory hormones as potential mediators of the seasonal shifts in immune status. Retrospectively, the medical records of a large group of rhesus monkeys were examined to determine whether a common disease (campylobacteriosis) in this species shows a seasonal pattern of prevalence. Results of the study showed that there was a seasonal shift in the frequency of cells expressing TH1 cytokines (interleukin-2 and interferon-gamma) versus the TH2 prototype cytokine (interleukin-4) by peripheral blood mononuclear cells (PBMC) collected during the winter and summer. The frequency of TH1-type cytokine synthesis in the summer was markedly greater than in the winter whereas TH2-type cytokine expression did not vary between the two seasons. The proliferative response of PBMC to mitogens and natural killer cell activity of PBMC also varied with the season. Several hormones (testosterone, leptin, and prolactin) that modulate immune function exhibited circannual patterns of secretion. The prevalence of Campylobacter infections was higher in the spring than during the summer, fall, or winter. The data suggest that seasonal fluctuations in immune system status may alter the ability of primates to successfully respond to pathogens, and this may be related to circannual patterns of secretion of immunomodulatory hormones.

Immunogenicity of the B monomer of Escherichia coli heat-labile toxin expressed on the surface of Streptococcus gordonii

The B monomer of the Escherichia coli heat-labile toxin (LTB) was expressed on the surface of the human oral commensal bacterium Streptococcus gordonii. Recombinant bacteria expressing LTB were used to immunize BALB/c mice subcutaneously and intragastrically. The LTB monomer expressed on the streptococcal surface proved to be highly immunogenic, as LTB-specific immunoglobulin G (IgG) serum titers of 140,000 were induced after systemic immunization. Most significantly, these antibodies were capable of neutralizing the enterotoxin in a cell neutralization assay. Following mucosal delivery, antigen-specific IgA antibodies were found in feces and antigen-specific IgG antibodies were found in sera. Analysis of serum IgG subclasses showed a clear predominance of IgG1 when recombinant bacteria were inoculated subcutaneously, while a prevalence of IgG2a was observed upon intragastric delivery, suggesting, in this case, the recruitment of a Th1 type of immune response.

Macrophage colony-stimulating factor can modulate immune responses and attract dendritic cells in vivo

Studies have indicated that professional APCs in the periphery, such as dendritic cells and macrophages, play an important role in initiating DNA vaccine-specific immune responses. To engineer the immune response induced by DNA vaccines in vivo we investigated the modulatory effects of codelivering growth factor genes for the hematopoietic APCs along with DNA vaccines. Specifically, we examined the effects on the antigen-specific immune responses following the codelivery of the gene expression cassettes for M-CSF, G-CSF, and GM-CSF along with HIV-1 DNA immunogen constructs. We observed that coimmunization with GM-CSF increased the antibody response and resulted in a significant enhancement of lymphoproliferative response. Furthermore, among all coinjection combinations, we found that M-CSF coinjections resulted in a high level of CTL enhancement. This enhancement of CTL responses observed from the coinjection with M-CSF was CD8+ T cell dependent and was associated with the presence of CD11c+ cells at the site of injection and with the antigen-specific induction of the beta-chemokine MIP-1beta, suggesting a role for this chemokine in CTL induction. These results suggest that hematopoietic growth factors should be further studied as potential adjuvants for in vivo modulators of immune responses.

Vaccination with heat-killed Listeria as adjuvant reverses established allergen-induced airway hyperreactivity and inflammation: role of CD8+ T cells and IL-18

Asthma is a respiratory disorder characterized by airway hyperreactivity (AHR) and inflammation and is associated with high serum IgE and overproduction of IL-4, IL-5, and IL-13 by allergen-specific Th2 cells. Our previous studies demonstrated that heat-killed Listeria monocytogenes (HKL) as an adjuvant in immunotherapy successfully reversed ongoing Ag-specific Th2-dominated responses toward Th1-dominated responses, but it was unclear if such immune modulation could reverse ongoing, established disease in target organs such as the lung. In this paper we show that a single dose of Ag plus HKL as adjuvant significantly reduced AHR in a murine model for asthma and reversed established AHR when given late after allergen sensitization. HKL as adjuvant also dramatically inhibited airway inflammation, eosinophilia, and mucus production, significantly reduced Ag-specific IgE and IL-4 production, and dramatically increased Ag-specific IFN-gamma synthesis. The inhibitory effect of HKL on AHR depended on the presence of IL-12 and CD8+ T cells and was associated with an increase of IL-18 mRNA expression. Thus, our results demonstrate that HKL as an adjuvant for immunotherapy mediates immune deviation from a pathological Th2-dominated response toward a protective immune response in peripheral lymphoid tissues and in the lungs and may be clinically effective in the treatment of patients with established asthma and allergic disease.

Desmoglein-1-specific T lymphocytes from patients with endemic pemphigus foliaceus (fogo selvagem)

Fogo selvagem (FS), the endemic form of pemphigus foliaceus, is a cutaneous autoimmune disease characterized by subcorneal blistering of the epidermis and the production of autoantibodies against the desmosomal antigen desmoglein-1 (Dsg1). Previously, we showed that mice injected with autoantibodies from FS patients develop a skin disease that reproduces the clinical, histological, and immunological features of FS, indicating that autoantibodies play an essential role in the development of this disease. The purpose of this study was to characterize the autoimmune T-cell response associated with FS. We provide here the first evidence, to our knowledge, that the great majority of FS patients have circulating T lymphocytes that specifically proliferate in response to the extracellular domain of Dsg1. Long-term T cells developed from these patients also responded to Dsg1, and this antigen-specific response was shown to be restricted to HLA-DR molecules. These Dsg1-reactive FS T cells exhibited a CD4-positive memory T-cell phenotype and produced a T helper 2-like cytokine profile. These findings represent the initial steps in defining the role of T cells in FS autoimmunity.

Increased frequency of interferon-gamma-producing peripheral blood CD4+ T cells in chronic hepatitis C virus infection

OBJECTIVES

To determine the profile of cytokine secretion by CD4+ T helper (Th) cells in chronic hepatitis C virus (HCV) infection, we used flow cytometry to determine the percentage of interferon (IFN)-gamma and interleukin (IL)-4 producing cells from CD4+ T lymphocytes in peripheral blood obtained from patients chronically infected with HCV.

METHODS

Peripheral blood mononuclear cells isolated from 89 HCV infected subjects (22 asymptomatic carriers, 56 patients with chronic hepatitis, and 11 patients with liver cirrhosis) and 24 healthy controls were stained with surface CD4 and intracellular IFN-gamma and IL-4. Serum soluble IL-2 receptor (sIL-2R) levels were analyzed by ELISA.

RESULTS

The frequency of IFN-gamma producing CD4+ cells in asymptomatic HCV carriers, patients with chronic hepatitis, and patients with liver cirrhosis were significantly higher than those of healthy controls (p<0.01, respectively). In contrast, the percentages of IL-4-producing CD4+ cells were very low, and there were no significant correlations with disease progression. A significant elevation in serum sIL-2R levels was found in chronic HCV infection compared to healthy controls, and serum sIL-2R levels significantly correlated with the frequency of IFN-gamma-producing cells.

CONCLUSIONS

In HCV infected subjects, both serum sIL-2R and IFN-gamma are increased in chronic HCV infection no matter the stage of disease, meaning they are no different in asymptomatic carriers, patients with chronic hepatitis, and patients with liver cirrhosis, and that Th1 cytokine or Th1 cells may participate in the pathogenesis of liver damage in chronic HCV infection.

Immunostimulatory properties of the Leishmania infantum heat shock proteins HSP70 and HSP83

Emerging evidence indicates that the heat shock proteins (HSPs), a set of highly evolutionary conserved proteins, are playing essential roles in both normal processes of the immune system and specific immune responses. In a previous work, we demonstrated that the Leishmania infantum HSP70 possesses remarkable immunostimulatory properties. In the present work, we have extended the study to another HSP from this parasite, the HSP83. We show that this protein also has an adjuvant effect to an accompanying protein by stimulation of the humoral response when both proteins are fused and co-administered to BALBjc mice. The analysis of the IgG isotypes, IgG1 and IgG2a, indicated that the immunisations with the Leishmania HSPs, mainly the HSP70, potentiate a Thl-type response. It was found that the amino-terminal domain of the HSP70, the most evolutionary conserved region of the molecule, maintains the ability to stimulate the humoral response, whereas the carboxyl-terminal domain does not have a similar effect. Unexpectedly, we found that the L. infantum HSP70 and HSP83 recombinant proteins stimulated the proliferation of spleen cells from unprimed BALB/c mice. Remarkably, this proliferation was abolished either by thermal denaturing of the proteins or by using specific antibodies. The use of the T-cell inhibitor cyclosporin A in the splenocytes proliferation assays suggested that both T- and non-T-cells are stimulated by the Leishmania HSPs. These findings may be relevant for therapeutic and prophylactic applications.

Contribution of mast cells to the T helper 2 response induced by simultaneous subcutaneous and oral immunization

This work examines the contribution of mast cells to the synergistic enhancement of the T helper 2 (Th2) immune response elicited following simultaneous oral and subcutaneous (s.c.) immunization. The s.c. route induced a Th1-biased immune response, characterized by increased interferon-gamma (IFN-gamma) and immunoglobulin G2a (IgG2a) antibody production. In contrast, oral immunization stimulated a primarily Th2-type response in which interleukin-4 (IL-4) and IgG1 antibody production were dominant. Simultaneous immunization also triggered a Th2-biased response, the magnitude of which exceeded the additive effects of s.c. and oral immunization alone by greater than threefold. To analyse whether mast cells in gut-associated lymphoid tissue contributed to this synergistic response, mast cell-deficient mice WBB6F1-w/wv were studied. Whereas the primary response following simultaneously antigen administration was reduced only twofold in these animals compared with wild type controls WBB6F1-+/+ (suggesting that mast cells were not needed to initiate Th2 immunity), reconstitution with bone-marrow-derived mast cells from WBB6F1-+/+ mice resulted in a superoptimal response (suggesting that mast cells contribute to the magnitude and perpetuation of these Th2-biased responses).

The role of allergy in the development of asthma

Recent studies have shown that initial sensitization to airborne environmental allergens occurs typically in early childhood, but subsequent progression to persistent atopic asthma, which may not manifest for several years, is restricted to only a subset of atopics. The key to establishing the link between atopy and asthma lies in the development of persistent inflammation in the airway wall, resulting in structural and functional changes in local tissues which are responsible for the symptoms of the disease. This review summarizes recent findings on the nature of the cellular and molecular mechanisms underlying this process, and addresses the issue of why the intensity and duration of these tissue-damaging responses in the airway wall apparently exceeds the critical threshold required for development of persistent asthma in only a minority of allergy sufferers.

DNA priming-protein boosting enhances both antigen-specific antibody and Th1-type cellular immune responses in a murine herpes simplex virus-2 gD vaccine model

It has previously been reported that herpes simplex virus (HSV)-2 gD DNA vaccine preferentially induces T-helper (Th) 1-type cellular immune responses, whereas the literature supports the view that subunit vaccines tend to induce potent antibody responses, supporting a Th2 bias. Here, using an HSV gD vaccine model, we investigated whether priming and boosting with a DNA or protein vaccine could induce both potent antibody and Th1-type cellular immune responses. When animals were primed with DNA and boosted with protein, both antibody and Th-cell proliferative responses were significantly enhanced. Furthermore, production of Th1-type cytokines (interleukin-2, interferon-gamma) was enhanced by DNA priming-protein boosting. In contrast, protein priming-DNA boosting produced antibody levels similar to those following protein-protein vaccination but failed to further enhance Th-cell proliferative responses or cytokine production. DNA priming-protein boosting resulted in an increased IgG2a isotype (a Th1 indicator) profile, similar to that induced by DNA-DNA vaccination, whereas protein priming-DNA boosting caused an increased IgG1 isotype (a Th2 indicator) profile similar to that seen after protein-protein vaccination. This result indicates that preferential induction of IgG1 or IgG2a isotype is determined by the type of priming vaccine used. Thus, this study suggests that HSV DNA priming-protein boosting could elicit both potent Th1-type cellular immune responses and antibody responses, both of which likely are important for protection against HSV infection.

Cutting Edge: Mouse IgG1 Antibodies Comprise Two Functionally Distinct Types That Are Differentially Regulated by IL-4 and IL-12

IL-4-dependent and -independent IgG1 Abs differ in their ability to induce mast cell degranulation as measured by passive cutaneous anaphylaxis (PCA). Mice immunized with OVA or PIII (fraction of Ascaris suum) produced high titers of IgG1 as shown by ELISA and PCA. In contrast, another A. suum fraction, PI, elicited IgG1 Abs with no PCA activity. IgG1 with anaphylactic activity required IL-4, as IgG1 responses to OVA and PIII in IL-4−/− mice gave no PCA. PI-specific IgG1 was IL-4-independent, because no difference was found between the responses of IL-4−/− and IL-4+/+ mice. Significant PCA reactions were elicited, however, with PI-specific IgG1 from IL-12−/− or anti-IFN-γ Ab-treated mice, although less Ab was measured by ELISA. These results indicate that one type of IgG1 has anaphylactic activity and its synthesis is IL-4-dependent, being inhibited by IL-12 or IFN-γ; the other lacks this activity and its synthesis is stimulated by IL-12 or IFN-γ.

Inhibition of immunoglobulin E production by Poncirus trifoliata fruit extract

Immunoglobulin E (IgE) is the principal immunoglobulin involved in immediate hypersensitivities and chronic allergic diseases. The effect of an aqueous extract of Poncirus trifoliata (L) Raf. (Rutaceae) fruits (PTFE) on in vivo and in vitro IgE production was investigated. PTFE dose-dependently inhibited the active systemic anaphylaxis and serum IgE production induced by immunization with ovalbumin, Bordetella pertussis toxin and aluminum hydroxide gel. PTFE strongly inhibited interleukin 4 (IL-4)-dependent IgE production by lipopolysaccharide-stimulated murine whole spleen cells. In the case of U266 human IgE-bearing B cells, PTFE also showed an inhibitory effect on the IgE production. These results suggest that PTFE has an anti-allergic activity by inhibition of IgE production from B cells.

Antigen-specific signaling by a soluble, dimeric peptide/major histocompatibility complex class II/Fc chimera leading to T helper cell type 2 differentiation

Interaction between a T cell receptor (TCR) and various ligands, i.e. , anti-TCR antibodies, superantigens, peptides, or altered peptide ligands in the context of major histocompatibility complex (MHC) molecules can trigger different T helper cell (Th) effector functions. Herein, we studied the T cell response induced by a soluble, dimeric peptide/MHC class II chimera, namely hemagglutinin (HA)110-120/I-E(d)alphabeta/Fcgamma2a (DEF). We have previously demonstrated that the soluble DEF molecule binds stably and specifically to HA110-120-specific TCRs expressed by a T cell hybridoma. Administration of DEF in vivo induced differentiation of resting and activated peptide-specific T cells toward a Th2 response, as indicated by the increase of interleukin (IL)-4, IL-10, and specific immunoglobulin (Ig)G1 antibodies and decrease of IL-2, specific IgG2a antibodies, and cytotoxic T lymphocyte activity. In contrast to HA110-120 peptide presented by the DEF molecule to T cells, the nominal synthetic peptide induced a predominant Th1 response, and the PR8 virus-derived HA110-120 peptides induced a mixed Th1/Th2 response. Independent of antigen processing, soluble DEF was almost 2 logs more potent in stimulating cognate T cells than the nominal peptide. Polarization of cognate T cells toward the Th2 response occurred upon interaction of soluble DEF with TCR and CD4 molecules followed by early activation of p56(lck) and ZAP-70 tyrosine kinases, and negative signaling of the signal transducer and activator of transcription (STAT)4 pathway of Th1 differentiation. DEF-like molecules may provide a new tool to study the mechanisms of signaling toward Th2 differentiation and may also provide a potential immunotherapeutic approach to modulate autoreactive T cells toward protective Th2 immune responses.

Bruton’s Tyrosine Kinase Deficiency in Macrophages Inhibits Nitric Oxide Generation Leading to Enhancement of IL-12 Induction

We show that macrophages of X-linked immunodeficient mice with a mutant nonfunctional Bruton’s tyrosine kinase produce less NO than wild-type macrophages in response to a variety of stimuli. Induction of the inducible NO synthase (iNOS) protein, the transcription factor IFN regulatory factor-1 involved in iNOS expression, and the transcription factor STAT-1 involved in regulating IFN regulatory factor-1 induction are all poorer in X-linked immunodeficient than in wild-type macrophages. On the other hand, induction of IL-12 is higher in X-linked immunodeficient than in wild-type macrophages. Macrophage IL-12 induction is enhanced by iNOS inhibitors such as aminoguanidine and thiocitrulline and is inhibited by NO generation via sodium nitroprusside. There is relative enhancement of IFN-γ production by immune T cells from mice immunized under aminoguanidine cover. Our data thus suggest that Bruton’s tyrosine kinase participates in signaling for iNOS induction via IFN regulatory factor-1 in macrophages and that NO is an inhibitor of IL-12 induction.

Detection of canine cytokine gene expression by reverse transcription-polymerase chain reaction

Further characterization of the canine immune system will greatly benefit from the availability of tools to detect canine cytokines. Our interest concerns the study on the role of cytokines in canine visceral leishmaniasis. For this purpose, we have designed specific primers using previously published sequences for the detection of canine IL-2, IFN-gamma and IL10 mRNA by reverse transcription-polymerase chain reaction (RT-PCR). For IL-4, we have cloned and sequenced this cytokine gene, and developed canine-specific primers. To control for sample-to-sample variation in the quantity of mRNA and variation in the RT and PCR reactions, the mRNA levels of glyceraldehyde-3-phosphate dehydrogenase (G3PDH), a housekeeping gene, were determined in parallel. Primers to amplify G3PDH were designed from consensus sequences obtained from the Genbank database. The mRNA levels of the cytokines mentioned here were detected from ConA-stimulated peripheral mononuclear cells derived from Leishmania-infected dogs. A different pattern of cytokine production among infected animals was found.

Infection of mice lacking interleukin-7 (IL-7) reveals an unexpected role for IL-7 in the development of the parasite Schistosoma mansoni

A single intradermal administration of recombinant interleukin-7 (IL-7) has been shown to aggravate the course of murine schistosomiasis, to favor the development of Th2-associated antibodies specific for the parasite, and to alter migration kinetics and/or migratory route of the parasite within its vertebrate host. Here we show that after infection of IL-7-deficient mice with Schistosoma mansoni, the predominant parasite-specific humoral response follows a Th1 pattern, and the development of the parasite is greatly impaired. In IL-7-deficient mice, increased numbers of larvae reach the lungs and fewer larvae reach the liver, compared to control mice. In the absence of IL-7, female worms show an altered fecundity, leading to decreased numbers of eggs trapped in the tissues and to an amelioration of the pathology of the infected host. The most striking observation is the blockade of parasite growth in an IL-7-defective environment, leading to dwarf male and female worms. The results of this study have important implications for the role of IL-7 in the host-parasite relationship and show how parasites can disable or evade the host immune response.

Antigen-specific humoral and cellular immune responses can be modulated in rhesus macaques through the use of IFN-gamma, IL-12, or IL-18 gene adjuvants

DNA or nucleic acid immunization has been shown to induce both antigen-specific cellular and humoral immune responses in vivo. Moreover, immune responses induced by DNA immunization can be enhanced and modulated by the use of molecular adjuvants. To engineer the immune response in vivo towards more T-helper (Th)1-type cellular responses, we investigated the co-delivery of inteferon (IFN)-gamma, interleukin (IL)-12, and IL-18 genes along with DNA vaccine constructs. We observed that both antigen-specific humoral and cellular immune responses can be modulated through the use of cytokine adjuvants in mice. Most of this work has been performed in rodent models. There has been little confirmation of this technology in primates. We also evaluated the immunomodulatory effects of this approach in rhesus macaques, since non-human primates represent the most relevant animal models for human immunodeficiency virus (HIV) vaccine studies. As in the murine studies, we also observed that each Th1 cytokine adjuvant distinctively regulated the level of immune responses generated. Co-immunization of IFN-gamma and IL-18 in macaques enhanced the level of antigen-specific antibody responses. Similarly, co-delivery of IL-12 and IL-18 also enhanced the level of antigen-specific Th proliferative responses. These results extend this adjuvant strategy in a more relevant primate model and support the potential utility of these molecular adjuvants in DNA vaccine regimens.

Mucosal immunity and tolerance: relevance to vaccine development

The mucosal immune system of mammals consists of an integrated network of lymphoid cells which work in concert with innate host factors to promote host defense. Major mucosal effector immune mechanisms include secretory antibodies, largely of immunoglobulin A (IgA) isotype, cytotoxic T cells, as well as cytokines, chemokines and their receptors. Immunologic unresponsiveness (tolerance) is a key feature of the mucosal immune system, and deliberate vaccination or natural immunization by a mucosal route can effectively induce immune suppression. The diverse compartments located in the aerodigestive and genitourinary tracts and exocrine glands communicate via preferential homing of lymphocytes and antigen-presenting cells. Mucosal administration of antigens may result in the concomitant expression of secretory immunoglobulin A (S-IgA) antibody responses in various mucosal tissues and secretions, and under certain conditions, in the suppression of immune responses. Thus, developing formulations based on efficient delivery of selected antigens/tolerogens, cytokines and adjuvants may impact on the design of future vaccines and of specific immunotherapeutic approaches against diseases associated with untoward immune responses, such as autoimmune disorders, allergic reactions, and tissue-damaging inflammatory reactions triggered by persistent microorganisms.

On the Role of Feedback in Promoting Conflicting Goals of the Adaptive Immune System

We explored here the implications of two premises. 1) In their response over days or weeks to pathogen invasion, cells of the immune system combine several overlapping and perhaps contradictory goals. 2) The immune system has ways to monitor progress toward these goals via receptors that bind chemicals whose concentrations are related to such progress. We illustrate with simple mathematical models how such monitoring can lead to feedbacks that improve the efficiency of a given effector type in accomplishing its specialized task, and also how feedbacks can shift the balance among a variety of effectors toward a preponderance of the more effective. Specific suggestions are given for feedback molecules.

Asiasari radix inhibits immunoglobulin E production on experimental models in vitro and in vivo

Immunoglobulin (Ig) E is the principal Ig involved in immediate hypersensitivities and chronic allergic diseases. The hallmark of these disorders is increased IgE production. The effect of an aqueous extract of the roots of Asiasari radix (ARAE) on an in vivo and in vitro IgE production was investigated. ARAE dose-dependently inhibited the active systemic anaphylaxis and serum IgE production induced by immunization with ovalbumin, Bordetella pertussis toxin and aluminum hydroxide gel. ARAE strongly inhibited IL-4-dependent IgE production by lipopolysaccharide- stimulated murine whole spleen cells. In the case of U266 human IgE-bearing B cells, ARAE also showed an inhibitory effect on the IgE production. These results suggest that ARAE has an anti-allergic activity by inhibition of IgE production from B cells.

Delayed Clearance of Filarial Infection and Enhanced Th1 Immunity Due to Modulation of Macrophage APC Functions in xid Mice

Bruton’s tyrosine kinase (Btk) mutant CBA/N mice show delayed clearance of injected microfilaria (mf) compared with wild-type CBA/J mice. Anti-mf T cells from CBA/N mice make relatively more IFN-γ than those from CBA/J mice. The anti-mf T cell proliferative responses are also greater in CBA/N mice. This CBA/N immune phenotype is not restricted to filarial Ags, because immunization with pure proteins also yields T cell responses of greater proliferative magnitude skewed away from Th2 cytokines in CBA/N compared with CBA/J mice. The increased magnitude of CBA/N T cell proliferative responses is reflected in increases in both precursor frequencies and clonal burst sizes of responding Ag-specific T cells, and is independent of the source of re-stimulating APCs. Transfer of CBA/J peritoneal resident cells (PRCs) into CBA/N mice before pure protein immunization leads to a wild-type immune phenotype in the recipient CBA/N mice, with a reduction in the proliferative response and a relative decrease in the IFN-γ produced. When wild-type PRC subpopulations are similarly transferred, the wild-type immune phenotype is transferred by macrophages rather than by B cells. Transfer of wild-type PRCs into CBA/N mice before injection of mf also causes similar changes in the anti-mf T cell responses and enhances the clearance of mf. Thus, Btk is involved in critical macrophage APC functions regulating priming of T cells, and can modulate these responses in pathophysiologically relevant fashion in vivo.

Shifts in lung lymphocyte profiles correlate with the sequential development of acute allergic and chronic tolerant stages in a murine asthma model

T lymphocytes have a central regulatory role in the pathogenesis of asthma. We delineated the participation of lymphocytes in the acute allergic and chronic tolerant stages of a murine model of asthma by characterizing the various subsets of lymphocytes in bronchoalveolar lavage and lung tissue associated with these responses. Acute (10-day) aerosol challenge of immunized C57BL/6J mice with ovalbumin resulted in airway eosinophilia, histological evidence of peribronchial and perivascular airway inflammation, clusters of B cells and TCRgammadelta cells in lung tissue, increased serum IgE levels, and airway hyperresponsiveness to methacholine. In mice subjected to chronic (6-week) aerosol challenge with ovalbumin, airway inflammation and serum IgE levels were significantly attenuated and airway hyperresponsiveness was absent. The marked increases in lung B and T cell populations seen in the acute stage were also significantly reduced in the chronic stage of this model. Thus, acute ovalbumin challenge resulted in airway sensitization characteristic of asthma, whereas chronic ovalbumin challenge elicited a suppressed or tolerant state. The transition from antigenic sensitization to tolerance was accompanied by shifts in lymphocyte profiles in the lung and bronchoalveolar lavage fluid.

The new pemphigus variants

Pemphigus describes a group of autoimmune diseases characterized by blisters and erosions of the skin and mucous membranes, acantholysis by histology, and autoantibodies directed against epidermal cell surface components. Since the early 1970s, the following new clinical variants of pemphigus have been reported: pemphigus herpetiformis, IgA pemphigus, and paraneoplastic pemphigus. In recent years, significant data have been obtained from laboratory investigation on these rare and atypical variants, especially regarding their specific target antigens. We review these variants, their clinical presentations, histologic findings, immunopathology, target antigens, theories of pathogenesis, treatment modalities, and clinical courses.

Suppression of Antigen-Specific Th2 Cell-Dependent IgM and IgG1 Production Following Norepinephrine Depletion In Vivo

The mechanism by which the Th2 cell-dependent Ab response is modulated by the sympathetic neurotransmitter norepinephrine (NE) was investigated. Our model system used the severe combined immunodeficient (scid) mouse that was depleted of NE with 6-hydroxydopamine before reconstitution with a clone of β2-adrenergic receptor (β2AR)neg KLH-specific Th2 cells and resting trinitrophenyl (TNP)-specific β2ARpos B cells enriched from the spleens of unimmunized mice. Following challenge with TNP-keyhole limpet hemocyanin (KLH), Ab production in these mice was hapten-, carrier-, and allotype-specific as well as MHC restricted. Depletion of NE resulted in a 50–75% suppression of the primary anti-TNP IgM response compared with that of NE-intact controls, while the secondary IgM response returned to control levels. In contrast, both the primary and secondary anti-TNP IgG1 responses were suppressed by 85 and 40%, respectively. Using NE-intact mice exposed to either a βAR- or αAR-selective antagonist, the effect of NE on the Ab response was shown to be mediated by the βAR. In addition, administration of a β2AR-selective agonist to NE-depleted mice partially reversed the suppressed Ab response that resulted from NE depletion. Expression of the β2AR on TNP-specific B cells was confirmed by radioligand binding, immunofluorescence, and cAMP analysis. Also, while splenic histology was comparable in NE-intact and NE-depleted mice before Ag exposure, follicle expansion and germinal center formation were suppressed in NE-depleted mice after Ag exposure. Taken together, these results suggest that NE stimulation of the β2AR expressed on B cells is necessary for the maintenance of an optimal primary and secondary Th2 cell-dependent Ab response in vivo.

Cationic lipid DC-Chol induces an improved and balanced immunity able to overcome the unresponsiveness to the hepatitis B vaccine

Th1 and Th2 immune responses against antigens can be modulated by the use of adjuvants. Since antibody isotypes (IgG1 and IgG2a) and cytokines induced may reflect the Th differentiation taking place during the immune response, the humoral and cellular immune responses induced in mice against hepatitis B virus surface antigen (HBsAg) were examined when the antigen was either adsorbed to aluminum hydroxyde or administered with a new adjuvant the cationic lipid 3beta-[N-(N',N'-dimethylaminoethane)carbamoyl]cholesterol (DC-Chol). The use of DC-Chol increased antibody responses in responding BALB/c mice, induced more consistent IgG1 and IgG2a antibody responses in OF1 mice and overcame the nonresponse to HBsAg in B10.M mice. Furthermore, DC-Chol was able to induce cellular immune responses to HBsAg. The DC-Chol induced a balanced Th1/Th2 response, which enabled mice to overcome the inherited unresponsiveness to HBsAg encountered with aluminum-adjuvanted vaccine. Thus, the DC-Chol provides a signal to switch on both Th1 and Th2 responses, which may have important implications for vaccination against hepatitis B virus, as well as for enhancing weak immunogenicity of other recombinant purified antigens in a nonresponder population.