The association between lung innate immunity and differential airway antigen- specific immune responses

The mechanisms involved in the differential regulation of airwayimmune responses in atopic versus non-atopic individuals arepoorly understood. In this study, the association between nonspecific immunity and the differential airway antigen-specificImmune responses was examined in a murine model. The disparityIn antigen-specific IgE and IgG2a productions between the twostrains of mice was observed to be significant. C57BL/6J micewere much more efficient than BALB/cJ mice in making IgE antibodyto Inhaled ovalbumin (OVA) antigen. On the contrary, BALB/cJmice did make more IgG2a antibodies than C57BL/6J mice to InhaledOVA. These findings suggest that in C57BL/6J mouse strain apredominant T_h 2 type of Immune response develops in responseto inhaled OVA antigen. In contrast, BALB/c mice mount a T_h1 type of immune response to aerosollzed OVA antigen. Furthermore,after lipopolysaccharlde (LPS) stimulation, the IL-12 mRNA expressionof lung-derived cells from BALB/cJ mice was higher than thatfrom C57BL/6J cells. However, the lung-derived cells of C57BL/6Jmice stimulated by LPS produced higher levels of IL-b and prostaglandinE than BALB/cJ lung-derived cells did. Therefore, our studydemonstrated that the difference of lung-derived cells in theirability to produce cytokine and prostaglandln between BALBIcJand C57BL/6J mice correlates well with the type of the airwayantigen-specific immune effector functions.     

Gr1+IL-4-producing innate cells are induced in response to Th2 stimuli and suppress Th1-dependent antibody responses

Alum is used as a vaccine adjuvant and induces T_h2 responsesand T_h2-driven antibody isotype production against co-injectedantigens. Alum also promotes the appearance in the spleen ofGr1+IL-4+ innate cells that, via IL-4 production, induce MHCII-mediated signaling in B cells. To investigate whether theseGr1+ cells accumulate in the spleen in response to other T_h2-inducingstimuli and to understand some of their functions, the effectsof injection of alum and eggs from the helminth, Schistosomamansoni, were compared. Like alum, schistosome eggs inducedthe appearance of Gr1+IL-4+ cells in spleen and promoted MHCII-mediated signaling in B cells. Unlike alum, however, schistosomeeggs did not promote CD4 T cell responses against co-injectedantigens, suggesting that the effects of alum or schistosomeeggs on splenic B cells cannot by themselves explain the T celladjuvant properties of alum. Accordingly, depletion of IL-4or Gr1+ cells in alum-injected mice had no effect on the abilityof alum to improve expansion of primary CD4 T cells. However,Gr1+ cells and IL-4 played some role in the effects of alum,since depletion of either resulted in antibody responses toantigen that included not only the normal T_h2-driven isotypes,like IgG1, but also a T_h1-driven isotype, IgG2c. These datasuggest that alum affects the immune response in at least twoways: one, independent of Gr1+ cells and IL-4, that promotesCD4 T cell proliferation and another, via Gr1+IL-4+ cells, thatparticipates in the polarization of the response.     

Human Th2-like cell clones induce IL-12 production by dendritic cells and may express several cytokine profiles

Previous studies have shown that human T_h2 cells, unlike theirmurine counterparts, retain the ability to produce IFN- uponactivation in the presence of exogenous IL-12. Here we firstextended this notion by showing that T_h2-like cell clones (T_h2C)are also capable of inducing IL-12 production by physiologicalantigen-presenting cells (APC); we next showed that these cellsmay express several distinct cytokine profiles depending uponthe activation signal and the type of APC with which they interact.We have analyzed the production of IL-4, IL-5 and IFN- by T_h2Cstimulated by either anti-CD3 mAb or exogenous IL-2, using peripheralblood monocytes or dendritic cells (DC) as accessory cells.We found that: (i) DC but not monocytes released IL-12 and promotedIL-12-dependent IFN- production upon interaction with anti-CD3-or IL-2-stimulated T_h2C and (ii) ligation of CD3 was requiredfor the production of IL-4 but not of IL-5 or IFN-. Thus, dependingupon the type of APC with which they interacted and the modeof activation, T_h2C, expressed four distinct cytokine profiles:(i) IL-4 + IL-5, in response to anti-CD3 + monocytes; (ii) IL-4,IL-5 + IFN-, in response to anti-CD3 + DC; (iii) IL-5 + IFN-,in response IL-2 + DC; and (iv) IL-5 alone, in response to IL-2+ monocytes. The ability of human T_h2-like cells to induce IL-12production and to release the proinflammatory cytokines IFN-yandIL-5 upon IL-2-driven interactions with APC may contribute toexplain how local infection exacerbates Th2-mediated diseases,like bronchial asthma and atopic dermatitis.     

Specific decrease of Th1-like activity in mice with plasma cell tumors

Previously we examined the ability of the host's immune responsesto regulate Ig production in an IgE-secreting murine plasmacell tumor (B53). In the present study we have examined thereverse phenomenon, in that we have investigated the effectsof this and other plasma cell tumors on the immune responsesof their hosts. We found that splenocytes from plasma cell tumor-bearingmice demonstrate decreased proliferation in response to polyclonalstimulation by either Con A or a combination of PMA and calciumionophore (A23187 [GenBank] ). Fractionation of the splenocytes demonstratedthat this reduction in proliferation was confined to CD4⁺T cellsand that the proliferation of CD8⁺ T cells was unaffected. Inorder to determine whether the down-modulatory effects of thetumor were confined to a particular CD4⁺helper T cell subset,we examined the production of cytokines representing the T_h1subset (IL-2 and IFN-) and the T_h2 subset (IL-4 and IL-10) fromstimulated splenocytes and from stimulated enriched splenicT cells. We found that both stimulated splenocytes and T cellsfrom plasma cell tumor-bearing mice produced lower levels ofthe T_h1 cytokines IL-2 and IFN- compared with normal cultures,demonstrating that T_h1-like responses are inhibitsed in thehosts of these tumors. However, no alterations in the productionof the T_h2 cytokines IL-4 and IL-10 were observed in these stimulatedsplenocyte or T cell cultures from the tumor-bearing mice. Thus,our data demonstrate that plasma cell tumors induce a decreasein the immune responsiveness of their hosts, and this decreaseis restricted specifically to T_h1-like activity, with the T_h2-likeactivity and CD8⁺T cell proliferative responses remaining intact.     

Role of macrophages and {alpha}{beta} T lymphocytes in early interleukin 10 production during Listeria monocytogenes infection

Immunity to intracellular bacteria including Listeria monocytogenesis determined by T_h1 cells and CD8 T cells which produce interferon_h.Here we show that high levels of IL-10 are released by splenocytesfrom mice infected with L. monocytogenes. IL-10 was detectedon day 1 after infection, peaked on day 4, and subsequentlydeclined. Cell separation studies and experiments with RAG-1-deficientmice, which do not possess mature B cells or T cells, revealedthat the macrophage Is the major cellular source of early IL-10production. Elevated IL-10 production in RAG-1 mutants and TCRßmutants, but not in TCR mutants, Is consistent with an inhibitionof macrophage IL-10 release by ß T cells. High IL-10production was also seen after infection with another intracellularbacterium, Mycobacterlum bovis. Since IL-10 Inhibits T_h1 cellresponses, certain pathogens might use induction of this cytokineas an evasion mechanism from the protective Immune responseof the host. However, our findings showing high levels of IL-10production in infectious models which are dominated by T_h1 cellresponses suggest that IL-10 alone is insufficient for directingT_h0 differentiation into the T_h2 cell pathway. These findingstherefore challenge the view of IL-10 as a unique and decisivedetermlnator of the T_h2 cell pathway.     

B7 2 (CD86) is essential for the development of IL-4-producing T cells

The CD28/CTLA-4 ligands, B7–1 (CD80) and B7–2 (CD86),provide a co-stimulatory signal necessary for optimal T cellactivation. We have examined the effect of blocking B7–1and B7–2 in an in vitro system using ovalbumin-specificT cells from ß TCR-transgenic mice. This system allowedus to examine the interaction of B7 co-stimulators on physiologicantigen-presenting cells (APC) with antigen-specific T helperprecursor (T_hp) cells. We report that blocking T_hp/B7–1or B7–2 interactions in a primary response differentiallyaffects the cytokine profile observed in a secondary stimulation,even in the absence of additional anti-B7 antibody. Engagementof B7–2 in the primary stimulation was found to be essentialfor production of the T_h2 cytokine, IL-4, but not the T_h1 cytokines,IL-2 and IFN-, in a secondary stimulation. Conversely, inclusionof the anti-B7–1 mAb in cultures using highly purifiednaive T cells increased levels of IL-4 and significantly depressedlevels of IFN-, upon re-stimulation. The effect of the anti-B7–2mAb in reducing IL-4 production could be overcome by the additionof recombinant IL-4 in the primary stimulation. The effectsof the anti-B7–2 mAb appear to be due to blocking andnot cross-linking, as F(ab) fragments mimicked the intact antibody.Taken together, our data demonstrate that the interaction betweenThp and B7–2 favors the development of T_h2 cells.     

Co-activation of naive CD4+ T cells and bone marrow-derived mast cells results in the development of Th2 cells

Activation of nalve dense CD4⁺ T cells by plate-bound anti-CD3antibodies favors the development of T_h1 cells which, upon re-stimulation,produce significant amounts of INF- but no IL-4. However, co-activationof such naive T cells in the presence of IgE [anti-dlnitrophenyl(DNP)]-loaded bone marrow-derived mast cells (BMMC) on platescoated with anti-CD3 antibodies and DNP-BSA led to the developmentof IL-4-produclng T_h2 cells. The same result could be observedif irradiated (800 rad) BMMC were applied as co-stimulators.Moreover, BMMC could be replaced by the supernatant of IgE-activatedBMMC suggesting that a soluble mediator, presumably IL-4, wasresponsible for this effect. This assumption was substantiatedusing neutralizing anti-IL-4 antibodies which abolished theBMMC-medlated T_h2 development in all cases. Addition of IL-12,a cytokine that was shown to antagonize the T_h2-promoting effectof IL-4 in vivo, could not inhibit the development of IL-4-producingT cells, but gave rise to a T cell population which producedrelatively high amounts of IL-4 and IFN-. Since BMMC representthe in vitro equivalent of mucosai mast cells these data suggestthat IgE-activated mucosai mast cells can bias an emerging Tcell dependent Immune response towards a T_h2 dominated reactionby the initial production of IL-4.     

Functional CD4+T cell subsets defined by expression of CD45RC and NTA260 antigens and age-associated polarization in murine lupus

Using two mAb, one specific to the alternative exon 6-dependentepitope of CD45 molecules(JH6.2) and one a natural thymocytotoxicautoantibody (NTA) with an unknown reactive epitope (NTA260),we subdivided splenic CD4⁺ T cells from 2-month-old BALB/c miceinto five phenotypically distinct subsets. CD45RC⁺NTA260^–(SI) cells were phenotypically analogous to CD4⁺ T cells predominatingin newborn mice and produced a significant amount of IL-2, butnot so IL-4, IL-10 or IFN- when stimulated with immobilizedanti-CD3 mAb in vitro. They appeared to consist mainly of naiveT_hP cells. The CD45RC⁺;NTA260⁺ (S II) subset also produced IL-2,but not other cytokines; however, the IL-2 levels produced weremuch higher than seen with the S I subset, thereby suggestingthe predominance of further maturated T_hP cells. The D45RC^–NTA260⁺(S III) subset mainly produced IL-4, IL-10, IFN- and less IL-2,and contained memory cells that helped the secondary antibodyresponse to a recall antigen, and hence contained T_h2 and probablya mixture of T_h0 and T_h1 cells. The CD45RC^–NTA260^–(S IV) subset was a poor responder to the immobilized anti-CD3mAb. The CD45RC^brightNTA260^dull(S V) subset consisted of a smallnumber of cells that were phenotypically analogous to activatedCD4⁺ T cells. While an age-associated decrease in the proportionof S I and less markedly in S II and in turn increase in S IIIsubsets of CD4⁺ T cells occurred in normal BALB/c mice, autoimmunedisease-prone (NZBxNZW)F₁ mice showed a marked age-associateddecrease in the proportion of not only S I, II but also IIIsubsets. As aged (NZBxNZW)F₁ mice carry CD4⁺ T helper cellsfor IgG anti-DNA antibody production, such age-associated polarizationto the S IV subset appears to be critical in the pathogeneslsof autoimmune disease in these mice.     

Administration of IL-12 during ongoing immune responses fails to permanently suppress and can even enhance the synthesis of antigen-specific IgE

The synthesis of antibodies of the IgE isotype in mice largelydepends on IL-4, a cytokine that is released by T lymphocytesof the T_h2 subtype. IL-12 is a cytokine considered to directT_h cell development into a T_h1 direction and to suppress T_h2responses including the synthesis of IgE. Here we report aboutthe influence of IL-12 on the IgE response of mice immunizedwith protein antigens adsorbed to aluminum hydroxide. To avoidproblems with the detection of IgE caused by an excess of competitiveIgG antibodies produced in IL-12-treated mice, serum IgE wasfirst extracted from the serum by plate-bound anti-lgE mAb andthen determined either as total IgE or as antigen-specific IgEby using biotinylated anti-IgE or biotinylated antigen. Dependingon the strain of mice and the dose of IL-12 injected togetherwith the antigen, IL-12 can either temporarily suppress or augmentthe synthesis of (antigen-specific) IgE antibodies. This appliesfor CBA/J mice immunized six times in biweekly intervals withminute (0.1 µg/injection) or three-times with large (5µg/injection) amounts of the bee venom allergen phospholipaseA₂ (PLA₂. Under both conditions the antibody response is characterizedby the production of predominantly IgG1 as well as IgE but verylittle IgG2a, IgG2b and IgG3 antibodies. Simultaneous applicationof low doses of IL-12 (1 or 10 ng/day) led to a 2- to 4-foldenhancement of IgE production (PLA₂-specific IgE or total IgE).Only a high dose of 1 µg IL-12/day resulted in a 3- to10-fold reduction of the IgE response. This suppression wasnot stable, however, because the synthesis of IgE antibodieswas stimulated to a high level when these mice subsequentlyreceived a second course of immunizations in the absence ofIL-12. Likewise, the synthesis of IgE was only temporarily suppressedby IL-12 treatment in CBA/J mice immunized with keyhole limpethemocyanin (KLH) as antigen. However, application of low (10ng/day) or high (1 ng/day) doses of IL-12 during the primarycourse of immunizations of CBA/J mice with KLH suppressed theIgE response slightly or strongly respectively. In strikingcontrast, the KLH-specific IgE response of BALB/c mice was upregulatedeven when high doses of IL-12 (1 µg/day) were injectedsimultaneously with the immunizations. Thus, these results demonstratea great variability regarding the influence of IL-12 treatmenton ongoing IgE responses in vivo.     

Differentiation of human single-positive fetal thymocytes in vitro into IL-4- and/or IFN-{gamma}-producing CD4+ and CD8+ T cells

In this study we have investigated the capacity of human fetalthymocytes to differentiate in vitro into subsets of T cellswith polarized T_h1 or T_h2 cytokine profiles. Stimulation offreshly isolated human fetal thymocytes with anti-CD3 mAb, cross-linkedonto CD32,CD58,CD80-expressing mouse fibroblasts and subsequentculture in the presence of exogenous rIL-2 for 6 days, inducedthe production of both IL-4 and IFN-, which was mainly producedby CD4⁺ single-positive (SP) and CD8⁺ SP cells respectively.Addition of rIL-4 during priming augmented IL-4 production incultures of human fetal thymocytes, which was mainly due toan increased production of IL-4 by CD8SP cells. In contrast,addition of IL-4 to the cultures only slightly enhanced IL-4production and had little effect on frequencies of IL-4-producingCD4SP cells. Both CD4SP and CD8SP cells produced IL-5, IL-10and IL-13 at comparable levels, following priming in the presenceof rIL-4. Priming in the presence of rIL-12 strongly enhancedthe production of IFN- in both CD4SP and CD8SP cells. No correlationbetween expression of CD27, CD30 and CD60, and a particularcytokine profile of differentiated thymocytes could be demonstrated.Together, these results demonstrate the full capacity of fetalhuman thymocytes to differentiate into cytokine-producing Tcells in a priming milieu with appropriate stimulatory moleculesand exogenous cytokines. In addition, CD4SP thymocytes rapidlydifferentiate into polarized T_h2 cells following stimulationin vitro in the absence of exogenous rIL-4.     

Brucella abortus induces a novel cytokine gene expression pattern characterized by elevated IL-10 and IFN-{gamma} in CD4+ T cells

Immunization of BALB/c mice with killed Brucella abortus (BA)has previously been shown to Increase serum lgG2a levels andlong-term T cell clones from these mice secrete T_h1-associatedcytokines: IFN- and IL-2 but not IL-4 or IL-5. We analyzed cytokinegene expression following primary immunization with BA to determinewhen CD4⁺ T cells first express cytokine genes and whether specifichypothesized cytokine patterns (e.g. T_h precursor, T_h0) couldbe identified prior to a T_h1-like pattern. Our results demonstrateda highly consistent and novel pattern of T_h 1/T_h2 cytokine geneexpression characterized by elevated IL-10 and IFN- in CD4⁺T cells which rapidly manifests itself and is sustained forat least 10 days after immunization. No elevation in IL-2 cytokinegene expression was observed and treatment of BA-immunlzed micewith blocking anti- IL-2 antibodies had no effect on the cytokinegene expression pattern, although treatment with anti-IFN antibodiesresulted in increased IL-4, IL-5, and IL-9 cytoklne gene expression,In the absence of any change In IFN- or IL-10 as early as 4days after immunization. These results suggest that a wholepathogen may trigger sufficient costimulatory signals to rapidlyinduce effector T cells in the absence of elevated IL-2 andthat IL-10 Is specifically elevated in certain T_h1-like responses.     

Suppression of serum IgE response and systemic anaphylaxis in a food allergy model by orally administered high-dose TGF-beta

Some epidemiological or association studies suggest that transforming growth factor-beta (TGF-beta) in breast milk may be a decisive factor in diminishing the risk of allergic diseases during infancy. The observations have prompted us to investigate whether TGF-beta, when taken orally, can affect allergic immune responses. Repeated high-dose ovalbumin peptide (OVA) feeding was previously reported to induce OVA-specific IgE production and an anaphylactic reaction after intravenous challenge of OVA in OVA-TCR transgenic mice, which might represent a model for food allergy. By using this model, we showed here that oral administration of high-dose TGF-beta simultaneously with OVA feeding significantly inhibited the OVA-specific IgE elevation and anaphylactic reaction in OVA-TCR transgenic DO11.10 mice. These effects were associated with suppression of OVA-specific IL-4 production and GATA-3 expression and with up-regulation of IFN-gamma production and T-bet expression by splenocytes. Intra-peritoneal injection of anti-TGF-beta-neutralizing antibody abolished the inhibitory effects of orally administered TGF-beta on the serum IgE response and anaphylactic reaction after OVA feeding in DO11.10 mice. Interestingly, oral administration of high-dose TGF-beta suppressed activation-induced T cell death induced by OVA feeding in DO11.10 mice. We thus conclude that TGF-beta, when taken orally at high dose, has the capacity to modulate a food allergy-related reaction, at least in part, through its systemic activity.     

Anergy in vivo: down-regulation of antigen-specific CD4+ Th1 but not Th2 cytokine responses

Efficient immunologic tolerance, defined as antlgen-speclflcunresponslveness, can be peripherally induced by the l.v. Injectionof syngenelc splenocytes coupled with antigen using ethylenecarbodilmlde (ECDI). We have previously reported that unresponslvenessinduced via l.v. Injection of syngenelc splenocytes coupledwith intact, UV-lnactlvated Theiler's murine encephalomyelitisvirus (TMEV-SP) resulted in ‘split tolerance’. Bothvtrus-speclflc delayed-type hypersensltlvlty and lgG2a levelswere inhibited, whereas lgG1 levels were increased when comparedwith sham tolerized controls. In the present report we demonstratethat tolerance induced by l.v. Injection of TMEV-coupled splenocytesresulted in antigen-specific inhibition of T cell proliferation,as well as IL-2 and IFN- production in response to both wholeTMEV and the immunodomlnant viral epitope. Additionally, toleranceinduction resulted in abrogation of T_h1 -derived [IL-2, IFN-and LT/tumor necrosis factor-ß (TNF-ß)]cytokine mRNA expression in response to In vitro stimulationwith UV-inactlvated TMEV as determined by reverse transcrlptasepolymerase chain reaction. In contrast, expression of T_h2-derived(IL-4, IL-6 and IL-10) cytokine mRNA was not affected in tolerizedmice. Tolerance functioned directly at the level of CD4⁺ T_h1cells at both the induction and effector limbs as depletionof CD8⁺ T cells both prior to in vivo tolerizatlon or in vitroculture had no effect on inhibition of T_h1-specific responses.The mechanism of In vivo tolerance induction appeared to beanergy of CD4⁺ T_h1 cells since IL-2, IFN- and LT/TNF-ßmRNA expression as well as virus-specific prollferatlve responsescould be restored by addition of rlL-2 to In vitro culturesof tolerant, CD4⁺ T_h1 populations. These results suggest thatin vivo ‘split tolerance’ Induced by l.v. Injectionof ECDI-flxed, antigen-coupled splenocytes involves anergy ofTMEV-speclflc, CD4⁺ T_h1 lymphocytes and concomitant primingof T_h2 cells. The induction of antlgen-speclflc, in vivo anergyhas important implications in the design of therapeutic strategiesfor immunopathologic diseases mediated by T_h1 lymphocytes, especiallyT cell-mediated autoimmune disorders.     

IL-4 and anti-CD40 protect against Fasmediated B cell apoptosis and induce B cell growth and differentiation

Most T_h2 clones, when activated, produce IL-4 and express CD40ligand (CD40L) on their cell surface. Therefore, they can inducegrowth and differentiation of B cells by cognatehelp. In contrast,activated T_h1 clones, which produce IFN- and express both CD40Land Fas ligand (FasL) on their cell surface, often induce Bcell apoptotic cell death. Tounderstand the mechanism by whichT_h2 cells can induce B cell growth and differentiation in thepresence of FasL-positive cells, we stimulated B cells withIL-4, anti-IgM and/or anti-CD40 in the presence of anti-Fas.We report here that addition of anti-Fas strongly inhibitedanti-CD40-induced B cell proliferation without affecting anti-IgM-inducedB cell proliferation. Furthermore we showed that stimulationof B cells with anti-CD40 induced the expressionof Fas moleculeson the B cells ({small tilde}30%) and rendered them highly sensitiveto anti-Fas-mediated apoptotic cell death. Indeed, over 23%of anti-CD40-stimulated B cells showed hypodiploid DNA afterbeing incubated with anti-Fas, while >2% of anti-CD40-stimulatedB cells showed hypodiploid DNA after being incubated with mediumalone. We also showed that IL-4 enhanced expression of Fas onanti-CD40-induced B cells ({small tilde}50%), although co-stimulationwith anti-CD40 and IL-4 protected B cells from anti-Fas-mediatedapoptotic cell death and induced their growth and differentiation.Our present result might suggest that T_h2 cells could dominateover FasL-positive T_h1 cells by production of CD40L and IL-4,which in combination induce antibody production and inhibitthe T_h1 cell-mediated immune response.     

Induction of IgE responses using a recombinant mosquito salivary allergen rAed a 2 without adjuvant in mice.

BACKGROUND: Reactions to mosquito bites are a global problem. Several salivary proteins from Aedes (Ae.) aegypti, the most common mosquito species, have been cloned and expressed. Plasmid DNA vaccination has been shown to be effective in the downregulation of IgE responses. To investigate the in vivo antigenicity of these recombinant proteins and to study the mechanisms underlying plasmid DNA vaccination, a mouse model sensitized with a recombinant antigen has been developed. METHODS: BALB/c and C57BL/6 mice were injected intradermally with a 37-kD recombinant Ae. aegypti salivary allergen (rAed a 2) in the absence of adjuvant twice weekly for 8 weeks and then challenged twice with rAed a 2 at weeks 10 and 12. Serum rAed a 2-specific IgE, IgG1 and IgG2a were measured by ELISA. Intradermal tests were performed every 4 weeks. The binding capacity of rAed a 2-specific IgE to the native Aed a 2 was examined by immunoblotting. RESULTS: In both strains, sensitization with rAed a 2 induced a significant increase in IgE and IgG1, but not IgG2a. In all sensitized mice, a positive immediate skin reaction was apparent, while delayed-type hypersensitivity reactions were not observed. BALB/c mice produced significantly higher levels of IgE and IgG1 and larger wheals than C57BL/6 mice. The IgE antibodies elicited by rAed a 2 bound to not only rAed a 2 but also its natural form in mosquito saliva. CONCLUSION: (1) Repeated injections of rAed a 2 without adjuvant induce predominant Th2-type responses in mice. (2) BALB/c mice are better responders for IgE production than C57BL/6 mice. (3) rAed a 2 has identical allergenicity to its natural form.     

Effect of sublingual administration with a native or denatured protein allergen and adjuvant CpG oligodeoxynucleotides or cholera toxin on systemic T(H)2 immune responses and mucosal immunity in mice.

BACKGROUND: Sublingual immunotherapy has been recently used for allergic diseases, but its mechanisms are still unclear. OBJECTIVE: To examine the effect of sublingual administration of a native or denatured allergen alone or plus adjuvant on systemic T(H)2 responses and mucosal immunity in mice. METHODS: Naive or sensitized BALB/c mice were sublingually vaccinated biweekly for 3 weeks with ovalbumin (OVA) or urea-denatured OVA (CM-OVA) only or plus adjuvant CpG oligodeoxynucleotides (CpG) or cholera toxin (CT). Two weeks later, their specific serum IgG, IgG1, IgG2a, IgE, and saliva secretory IgA (SIgA) antibody responses and the cytokine profiles of spleen and cervical lymph node cells were investigated. RESULTS: Specific SIgA antibody responses were induced by vaccination with CM-OVA plus CpG or CT. Whereas vaccination with CM-OVA and CpG enhanced T(H)1 responses but inhibited IgE production, vaccination with CT and CM-OVA or OVA increased cervical lymph node cell production of interleukin (IL) 4, IL-5, and IL-6 and serum IgG1 antibody responses. In previously sensitized mice, sublingual vaccination with OVA or CM-OVA plus CT or CpG stimulated mucosal SIgA antibody responses, but did not enhance ongoing IgE antibody responses. CONCLUSIONS: Sublingual vaccination with OVA or CM-OVA plus adjuvant CT or CpG all can induce systemic and mucosal immunity, but CM-OVA plus CpG had the best prophylactic and therapeutic effects on IgE antibody production. It is likely that sublingual vaccines may have a role for the prophylaxis and immunotherapy of allergic reactions.     

Suppressive versus stimulatory effects of allergen/cholera toxoid (CTB) conjugates depending on the nature of the allergen in a murine model of type I allergy.

Recent reports have demonstrated that feeding small amounts of antigen conjugated to the B subunit of cholera toxin (CTB) suppress immune responses in experimental models of certain Th1-based autoimmune diseases. We have established a model of aerosol sensitization leading to Th2-mediated allergic immune responses in BALB/c mice. In the present study two different antigens, the dietary antigen ovalbumin (OVA) and the inhalant allergen Bet v 1 (the major birch pollen allergen), chemically coupled to recombinant CTB were tested for their potential to influence Th2-like immune responses. Intranasal administration of OVA-CTB prior to sensitization with OVA led to a significant decrease of antigen-specific IgE antibody levels, but a marked increase of OVA-specific IgG2a antibodies as compared to non-pretreated, sensitized animals. Antigen-specific lympho-proliferative responses in vitro were reduced by 65% in the pretreated group; IL-5 and IL-4, but not IFN-gamma, production were markedly decreased in responder cells of lungs and spleens of nasally pretreated mice. In contrast, mucosal administration of rBet v 1-CTB conjugates prior to sensitization led to an up-regulation of allergen-specific IgE, IgG1 and IgG2a, increased in vitro lympho-proliferative responses as well as augmented production of IL-5, IL-4, IL-10 and IFN-gamma. Intranasal administration prior to sensitization of unconjugated allergens showed also contrasting effects: OVA could not significantly influence antigen-specific antibody or cytokine production, whereas intranasal pretreatment with unconjugated Bet v 1 suppressed allergen-specific immune responses in vivo and in vitro. These results demonstrated that the two antigens--in conjugated as in unconjugated form--had different effects on the Th2 immune responses. We therefore conclude that the tolerogenic or immunogenic properties of CTB--and probably also other antigen-delivery systems--strongly depend on the nature of the coupled antigen-allergen.     

Linomide, an immunomodulator that inhibits Th1 cytokine gene expression

Linomide (LS-2616, quinoline-3-carboxamide) has strong immunomodulatingeffects in animal models, inhibiting toxic shock, progressiveautoimmune disease and cancer. In humans, linomide stronglyreduced the appearance of new lesions in multiple sclerosisyet enhanced immune responses after bone marrow transplantation.In contrast to these clear effects in vivo, attempts to showan effect of linomide in vitro have not been successful andits mode of action remains to be elucidated. Here we show thatat concentrations effective in vivo, linomide is active on humanperipheral blood mononuclear cells (PBMC), severely inhibitingthe induction by Staphylococcus aureus enterotoxin B of mRNAof three cytokine genes expressed in T_h1 cells, those for IFN-,IL-2, and tumor necrosis factor-ß. Yet, cell viabilitywas not affected by linomide. The extent of inhibition is dose-dependenton linomide. Linomide also blocked induction of IL-2 and IFN-mRNA by phytohemagglutinin. The inhibitory effect is expressedimmediately but can be enhanced significantly by a prolongedexposure of PBMC to linomide, reaching 10-fold. These resultssupport the concept that linomide antagonizes the activationof T_h1 cells during a cellular immune response.     

Autoimmunity to a pathogenic retinal antigen begins as a balanced cytokine response that polarizes towards type 1 in a disease-susceptible and towards type 2 in a disease-resistant genotype.

Susceptible, but not resistant, strains of rodents immunized for induction of experimental autoimmune uveitis (EAU) with the uveitogenic protein interphotoreceptor retinoid-binding protein (IRBP) exhibit a type 1 response at the time of disease expression. Here we investigate the evolution of this response using the prototypic EAU-susceptible and EAU-resistant mouse strains, B10.A and BALB/c. Disease severity and IRBP-specific responses (proliferation, cytokines and antibody isotypes) were evaluated 7, 14 and 21 days after uveitogenic immunization. B10.A mice initially exhibited an IgG1-dominated antibody response, and their lymph node cells produced IL-4 and IL-5 in addition to IFN-gamma. On day 14 and 21, however, the IgG2a isotype became predominant, and the primed lymph node cells produced mainly IFN-gamma and IL-12. B10.A mice developed EAU before day 14. BALB/c mice initially produced IL-12 and IFN-gamma in addition to IL-5, IL-4 and IL-10. At later time points IL-12 and IFN-gamma production diminished, and IL-4, IL-5 and IL-10 increased. An IgG1-dominated antibody response was maintained throughout. BALB/c mice failed to develop EAU even at day 21. Thus, both susceptible and resistant genotypes initially mount a balanced, type 0-like cytokine response to a uveitogenic challenge, that subsequently polarizes towards type 1 in the susceptible strain and towards type 2 in the resistant strain.