Acetaminophen enhances pruritus in a mouse model of contact dermatitis induced by suboptimal concentration of hapten

Acetaminophen (APAP) is one of the most commonly used drugs worldwide to reduce fever, particularly in children. It is generally considered to be a safe drug. However, a number of studies have shown that regular use of APAP increases the risk of developing allergic diseases. Nonetheless, no animal models have been used to investigate these findings. Therefore, we aimed to create an animal model of APAP-induced pruritus in mice. APAP (0.25% and 0.5%) was administered via drinking water daily from infancy, and a suboptimal concentration of 2,4,6-trinitrochlorobenzene (TNCB) was applied repeatedly to each ear three times a week for 7 weeks to evoke chronic allergic contact dermatitis. Neither 0.25% nor 0.5% APAP was overtly hepatotoxic after 73 days of daily administration. Repeated challenge with TNCB evoked increase in the number of scratching bouts compared to day 1. This increase in the number of scratching bouts was significant in 0.25% and 0.5% APAP groups but not in the group treated with TNCB alone. Daily administration of 0.5% APAP significantly increased in the number of scratching bouts compared to TNCB alone on day 29. This animal model will be useful for investigating the mechanism underlying the increased risk of development of eczema caused by regular APAP use and for examining safer and more effective therapy with APAP.

Histamine H(4) receptor antagonist ameliorates chronic allergic contact dermatitis induced by repeated challenge

BACKGROUND

The present study observed effects of the histamine H(4) receptor on chronic allergic contact dermatitis induced by repeated challenge in mice.

METHODS

Acute contact dermatitis was induced by single epicutaneous challenge of 2,4,6-trinitro-1-chlorobenzene (TNCB) to the ear. Chronic allergic contact dermatitis was developed by repeated epicutaneous challenge using TNCB on the dorsal back skin. H(4) receptor antagonist JNJ7777120 was administered to wild-type mice, while H(4) receptor agonist 4-methylhistamine was administered to histidine decarboxylase (HDC) (-/-) mice that synthesized no histamine.

RESULTS

HDC (-/-) mice did not differ phenotypically from HDC (+/+) mice, and H(4) receptor antagonist/agonist did not have clinical effects in terms of acute contact dermatitis reactions. H(4) receptor antagonist ameliorated skin eczematous lesions induced by repeated TNCB challenge in HDC (+/+) mice. On the contrary, H(4) receptor agonist exacerbated skin lesions exclusively in HDC (-/-) mice. Application of H(4) receptor agonist induced migration of mast cells and eosinophils in skin lesions, and H(4) receptor antagonist suppressed these changes. H(4) receptor was immunohistochemically detected on mast cells in eczematous lesions. Levels of interleukin (IL)-4, -5, and -6 in lesions were decreased, whereas levels of interferon-gamma and IL-12 were increased by H(4) receptor antagonistic activity. Serum Immunoglobulin E levels rapidly increased with repeated challenge, but decreased with H(4) receptor antagonist.

CONCLUSION

Because chronic allergic contact dermatitis is developed by H(4) receptor stimulation, H(4) receptor antagonists might represent new candidate drugs for treating chronic allergic contact dermatitis.

Effect of Formaldehyde Gas Exposure in a Murine Allergic Contact Hypersensitivity Model

To clarify the effect of formaldehyde (FA) gas exposure on contact hypersensitivity (CHS), CHS reactions against 2,4,6-trinitrochlorobenzene (TNCB) was studied in BALB/c mice with a low dose of FA gas exposure. The TNCB-induced CHS reactions were slightly suppressed by the FA gas exposure immediately after sensitization, whereas they were significantly enhanced and prolonged in mice continuously exposed to FA gas before and after sensitization. We showed that exposure to FA gas enhanced the Th2 dominant responses in draining lymph node (LN) in early stage of CHS. In contrast, T cell subsets and their intracellular cytokine production in the draining LN were similar during the early stage of CHS by FA gas exposure during the sensitization phase. The percentage of CD8+ T cells was increased, and the percentage of CD4+CD25+ T cells was decreased in the FA gas-exposed group at 72 hr after elicitation. These results indicate that FA gas-exposed might influence regulatory T cells. Furthermore, in the chronic CHS model that was repetitively elicited with TNCB, more intensive and prolonged CHS reactions, and increased numbers of mast cells were found in the FA gas-exposed group at 4 hr after elicitation than in the control group, FA gas exposure may alter the intensity of allergic CHS.

[Immunosuppressive effect of Tibetan medicine, Artemisia vestita Wall Extract]

OBJECTIVE

To assess the immunosuppressive effect of Artemisia vestita Wall Extract (AV-ext) on mice.

METHODS

The proliferative reaction of lymphocyte and the mixed lymphocytes reaction were used to determine the effects of AV-ext on the proliferation of mouse splenocyte in vitro and in vivo; Proliferative reaction of mouse splenocyte was used for detecting the effects of AV-ext on the level of IL-2 secreted by mouse activated splenocyte in vitro. Gelatin enzymogram method and adherence analytical method were employed to disclose the effects of AV-ext on mouse activated T-lymphocytes mobility and adherence.

RESULTS

1-100 microg/mL AV-ext exerted no obvious toxicity to mouse splenocyte, but it had obvious inhibitory effect on proliferative reaction of mouse splenocyte and mixed lymphocytes reaction induced by ConA. It also had obvious inhibitory effect on the level of IL-2 secreted by mouse activated splenocyte, on the production of MMP-9 by mouse activated T-lymphocytes, and on adherence. 150 mg/kg and 300 mg/kg of AV-ext, given to mouse per os for 7 days, could inhibit the proliferation of splenocyte and the secretion of MMP-9 by activated splenocyte of mouse.

CONCLUSION

AV-ext can inhibit the cellular immune reaction of mouse obviously.

Invariant NKT cells rapidly activated via immunization with diverse contact antigens collaborate in vitro with B-1 cells to initiate contact sensitivity

In cutaneous contact sensitivity there is an early elicited innate cascade of complement, mast cells, and platelets activated via IgM Abs. This response is required to initiate the elicitation of acquired classical contact sensitivity by leading to local recruitment of effector T cells. We recently performed in vivo experiments showing that collaboration is required between innate-like invariant Valpha14+ NKT cells (iNKT) and the innate-like B-1 B cell subset to induce this initiation process. Contact sensitization triggers iNKT cells to produce IL-4 to coactivate the B-1 cells along with specific Ag for production of the initiating IgM Abs. We now describe in vitro collaboration of iNKT and B-1 cells. Normal peritoneal B-1 cells, incubated in vitro with soluble Ag, and with 1-h in vivo immune iNKT cells producing IL-4, are activated to mediate the contact sensitivity-initiation cascade. The three components of this process can be activated by different Ag. Thus, 1-h iNKT cell activation, B-1 cell stimulation, and generation of immune effector T cells can be induced by sensitization with three different Ag to respectively generate IL-4 and Ag-specific IgM Abs, to recruit the Ag-specific effector T cells. These findings have relevance to allergic and autoimmune diseases in which infections can trigger exacerbation of T cell responses to allergens or to autoantigens.

Low zone tolerance induced by systemic application of allergens inhibits Tc1-mediated skin inflammation

BACKGROUND

The induction of tolerance may be a promising target of strategies aimed at preventing harmful allergic diseases. Low zone tolerance (LZT), induced by epicutaneous application of low doses of contact allergens, inhibits the development of T(C)1-mediated contact hypersensitivity (CHS).

OBJECTIVE

We evaluated the effect of systemic (oral, intravenous) administration of low amounts of haptens on specific immune reactions and tolerance induction.

METHODS

By using the mouse model of LZT, we analyzed immune reactions in vivo (skin inflammation) and T-cell responses in vitro after oral, intravenous, or epicutaneous application of low amounts of the contact allergen 2,4,6-trinitro-1-chlorobenzene (TNCB).

RESULTS

Subimmunogenic doses of TNCB applied orally and intravenously induced a significant tolerance reaction in vivo comparable to epicutaneously tolerized mice, indicating that LZT is a systemically mediated tolerance reaction. In vitro analysis in all models of LZT revealed the generation of IL-10 secreting, regulatory CD4+ T cells that were absolutely required for the development of hapten-specific CD8+ T(C)2 cells. Adoptive transfer experiments identified CD8+ T(C)2 cells as effector T cells of LZT inhibiting the development of CHS-promoting T(C)1 cells and consequently the manifestation of CHS. These suppressor CD8+ T(C)2 cells were found as well in skin-draining as in mesenteric lymph nodes and in the spleen of tolerized animals independent of the route of tolerization.

CONCLUSION

These data indicate that systemic uptake and presentation of small amounts of haptens (eg, contact allergens, drugs, metals) induce the development of LZT and thus prevent inappropriate activation of the immune system and protect from allergic diseases.

CLINICAL IMPLICATIONS

These findings will be of particular importance because tolerance induction by protocols applying subimmunogenic, low amounts of haptens may be used as tools for immunotherapy in allergic and autoimmune diseases.

A new synbiotic,Lactobacillus caseisubsp.caseitogether with dextran, reduces murine and human allergic reaction

We studied the development of atopic dermatitis-like skin lesions in NC/Nga mice and the allergic symptoms and blood patterns of healthy volunteers during the cedar (Cryptomeria japonica) pollen season in Japan following oral administration of a new synbiotic, Lactobacillus casei subsp. casei together with dextran. The combination of L. casei subsp. casei and dextran significantly decreased clinical skin severity scores and total immunoglobulin E levels in sera of NC/Nga mice that had developed picryl chloride-induced and Dermatophagoides pteronyssinus crude extract-swabbed atopic dermatitis-like skin lesions. During the most common Japanese cedar pollen season, synbiotic L. casei subsp. casei and dextran in humans led to no significant changes in total nasal and ocular symptom scores, in the levels of cedar pollen-specific immunoglobulin E, interferon-gamma and thymus and activation regulated chemokine or in the number of eosinophils in sera, whereas the placebo group showed a tendency for increased levels of cedar pollen-specific immunoglobulin E, thymus and activation regulated chemokine and number of eosinophils, and a decrease in interferon-gamma levels. Thus, the oral administration of synbiotic L. casei subsp. casei together with dextran appears to be an effective supplement for the prevention and treatment of allergic reactions.

Primary Defect in UVB-Induced Systemic Immunomodulation Does Not Relate to Immature or Functionally Impaired APCs in Regional Lymph Nodes

UVB irradiation of the shaved dorsal skin of mice can cause both local and systemic suppression of contact hypersensitivity responses; the former demonstrated by administration of the sensitizing Ag/hapten to the irradiated site and the latter by its administration at least 72 h later to distal unirradiated sites. The immunological basis of systemic immunomodulation is not clear. When haptens (trinitrochlorobenzene, FITC) were administered to the shaved ventral skin 4 days after irradiation (8 kJ/m(2)) to the shaved dorsum of BALB/c mice, CD11c(+)/FITC(+) cells in the skin-draining lymph nodes from control and irradiated mice produced on a per cell basis similar levels of IL-12 and PGE(2) were phenotypically mature and efficient at presenting FITC to lymphocytes from FITC-sensitized mice. Ag presentation by FACS-sorted CD11c(+) lymph node cells isolated 4 days after UVB irradiation was as efficient as were cells from unirradiated mice at presentation in vitro of an OVA peptide (OVA(323-339)) to CD4(+) cells from OVA-TCR-transgenic DO11.10 mice. Further, IFN-gamma levels were increased in the cultures containing CD11c(+) cells from UVB-irradiated mice, suggesting that inflammation may precede downstream immunosuppression. These results suggest that the primary cause of reduced contact hypersensitivity responses in mice in which UV irradiation and the sensitizing Ag are applied to different sites several days apart must originate from cells other than CD11c(+) APCs that directly or by production of soluble mediators (IL-12, PGE(2)) affect cellular responses in the nodes of UVB-irradiated mice.

In vivo transfection of a cis element 'decoy' against signal transducers and activators of the transcription 6 (STAT6) binding site ameliorates the response of contact hypersensitivity

We herein demonstrate that STAT6 plays an important role in the induction of not only acute contact hypersensitivity (CHS), but also chronic CHS in a mouse model using STAT6-deficient (STAT6(-/-)) mice. We, therefore, determine whether synthetic double-stranded DNA with a high affinity for STAT6 can be introduced in vivo as a decoy cis element to bind the transcriptional factor and block the induction of not only acute CHS but also chronic CHS. Treatment by the transfection of STAT6 decoy oligodeoxynucleotides (ODN), after the induction of 2,4,6-trinitrochlorobenzene or other haptens had a significant inhibitory effect on the induction of both acute CHS and chronic CHS. We thus examined the mechanism of the in vivo effect of the transfection of STAT6 decoy ODN in both acute and chronic CHS. In the histological analysis, the infiltration of eosinophils and degranulated mast cells, and the production of IL-4, IL-6 and eotaxin, but not IFN-gamma in the extracts from challenged skin significantly decreased by the transfection of STAT6 decoy ODN. We herein report the first successful in vivo transfer of STAT6 decoy ODN to inhibit acute and chronic CHS, thus providing a new therapeutic strategy not only for the treatment of CHS but also for atopic dermatitis.

Effects of TNCB sensitization in DS-Nh mice, serving as a model of atopic dermatitis, in comparison with NC/Nga mice

BACKGROUND

It has been predicted that a type-1 and type-2 helper T cell (Th1/Th2) imbalance exists in atopic dermatitis (AD). In DS-Nh mice, an AD mouse model, Staphylococcus aureus increases on the skin surface.

OBJECTIVE

To investigate whether the Th1-dominant response has an influence on the development of AD, we induced chronic allergic hypersensitivity with 2,4,6-trinitrochlorobenzene (TNCB ) in two AD mouse models: NC/Nga mice and DS-Nh mice. Th1 and Th2 cytokine production of splenocytes was assessed under stimulation with staphylococcal enterotoxin B (SEB) which induces a Th1 response in DS-Nh mice with or without TNCB sensitization.

METHODS

We examined clinical skin changes, transepidermal water loss (TEWL), the number of S. aureus on the skin and the serum IgE levels in these mice treated repeatedly with TNCB under conventional conditions (free of fur mites). The splenocytes of DS-Nh mice were cultured with SEB and the cytokine levels in the supernatants were measured by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Significant skin changes were observed on the skin even where TNCB was not applied in both mice treated with TNCB. Increases in S. aureus on the skin and serum IgE levels were detected in DS-Nh mice, but not in NC/Nga mice. In DS-Nh mice, IFN-gamma and IL-13 production of splenocytes increased in the mice treated with TNCB.

CONCLUSION

These results suggest that there might be a different mechanism of dermatitis induction between NC/Nga and DS-Nh mice. Th1 responses might play an important role in the development of dermatitis and increase in serum IgE levels in DS-Nh mice through an increase in IL-13 production.

B cells are not required for T cell priming in low zone tolerance to contact allergens and contact hypersensitivity

Low zone tolerance (LZT) to contact allergens is induced by epicutaneous exposure to haptens in subsensitizing doses resulting in an inhibition of contact hypersensitivity (CHS), which, in contrast, occurs after sensitization with immunogenic doses of allergens. Performing the protocol of tolerance induction resulted in robust LZT to allergens in B cell-deficient mice in vivo, indicating that B cells are not required for the induction and effector phase of LZT. However, CHS reactions in vivo were restricted in B cell-deficient mice as compared to wild-type (WT) mice. In contrast, analysis of hapten-specific T cell activation in vitro revealed a strong proliferative response of T cells derived from both WT and B cell-deficient sensitized mice. Similar to WT animals, T cells obtained from tolerized B cell-deficient mice produced a Tc2 cytokine pattern of LZT with high levels of IL-4 and IL-10, whereas sensitization of B cell-deficient mice resulted in the typical Tc1 cytokine profile of CHS. Adoptive transfer of CD8+ effector T cells from tolerized or sensitized B cell-deficient mice induced significant LZT or CHS reactions, respectively, in WT recipients, demonstrating that the development of hapten-specific effector CD8+ T cells of LZT and CHS is independent of B cells.

Termination of Antigen-Specific Immunity by CD95 Ligand (Fas Ligand) and IL-10

Following elimination of a foreign invader, the immune system must return to its normal quiescent levels. This process requires removal of reactive immune cells when they are no longer needed. We have explored the role of Fas/Fas ligand (FasL) in terminating immunity and demonstrate that mice defective in these proteins have prolonged immune responses. Studies demonstrate that termination of immunity occurs via the interaction of Fas(+) lymphoid cells with FasL(+) nonlymphoid cells at the site of Ag challenge. Our results also show that FasL is absent in quiescent tissue but is rapidly up-regulated during the local immune reaction. This occurs through the production of IL-10. Thus, FasL and IL-10 work in concert to eliminate inflammatory cells and control the duration of an immune response.

Dendritic cell immunization route determines CD8+ T cell trafficking to inflamed skin: role for tissue microenvironment and dendritic cells in establishment of T cell-homing subsets

The effector/memory T cell pool branches in homing subsets selectively trafficking to organs such as gut or skin. Little is known about the critical factors in the generation of skin-homing CD8+ T cells, although they are crucial effectors in skin-restricted immune responses such as contact hypersensitivity and melanoma defense. In this study, we show that intracutaneous, but not i.v. injection of bone marrow-derived dendritic cells induced skin-homing CD8+ T cells with up-regulated E-selectin ligand expression and effector function in contact hypersensitivity. The skin-homing potential and E-selectin ligand expression remained stable in memory phase without further Ag contact. In contrast, i.p. injection induced T cells expressing the gut-homing integrin alpha(4)beta(7). Although differential expression of these adhesion molecules was strictly associated with the immunization route, the postulated skin-homing marker CCR4 was transiently up-regulated in all conditions. Interestingly, dendritic cells from different tissues effectively induced the corresponding homing markers on T cells in vitro. Our results suggest a crucial role for the tissue microenvironment and dendritic cells in the instruction of T cells for tissue-selective homing and demonstrate that Langerhans cells are specialized to target T cells to inflamed skin.

Granulocyte-Macrophage Colony-Stimulating Factor-Based Melanoma Cell Vaccines Immunize Syngeneic and Allogeneic Recipients via Host Dendritic Cells

Subcutaneous injection of GM-CSF-expressing cancer cells into experimental animals results in protective cancer immunity. To delineate the mode of action of such vaccines, we used trinitrophenyl, the antigenic moiety of the contact allergen trinitrochlorobenzene, as surrogate Ag. Trinitrophenyl-derivatized bone marrow-derived dendritic cells were found to elicit a contact hypersensitivity response in syngeneic, but not in allogeneic recipients, compatible with their expected mode of direct Ag presentation. When expressing GM-CSF, haptenized M3 melanoma cells were also able to induce a contact hypersensitivity response but, in contrast to bone marrow-derived dendritic cells, not only in syngeneic but also in allogeneic recipients. This argues for a critical role of host APC. To identify their nature, we introduced the beta-galactosidase (betagal) gene into M3-GM cells. Their administration activated betagal-specific, L(d)-restricted CTL in syngeneic BALB/c mice. Evaluation of lymph nodes draining M3-GM-betagal injection sites revealed the presence of cells presenting the respective L(d)-binding betagal peptide epitope. Based on their capacity to activate betagal-specific CTL, they were identified as being CD11c(+) dendritic cells. These experiments provide a rational basis for the use of GM-CSF-based melanoma cell vaccines in an allogeneic setting.

Critical role of IL-10 in the induction of low zone tolerance to contact allergens

The development and mechanisms of tolerance to allergens are poorly understood. Using the murine low zone tolerance (LZT) model, where contact hypersensitivity (CHS) is prevented by repeated topical low-dose applications of contact allergens, we show that LZT induction is IL-10 dependent. IL-10 is required for the generation of LZT effector cells, that is, CD8+ regulatory T cells. Only T cells from tolerized IL-10+/+ mice or IL-10-/- mice reconstituted with IL-10 during LZT induction adoptively transferred LZT to naive mice and prevented CHS, whereas T cells from IL-10-/- mice failed to do so. The IL-10 required for normal LZT development is derived from lymph node CD4+ T cells, the only skin or lymph node cell population found to produce relevant amounts of IL-10 after tolerization. CD4+ T cells derived from IL-10+/+ mice, but not from IL-10-/- mice, allowed the induction of LZT in adoptively transferred T cell-deficient mice. Interestingly, IL-10 injections during tolerization greatly enhanced LZT responses in normal mice. Thus, the generation of CD8+ LZT effector T cells by CD4+ regulatory T cells via IL-10 may be a promising target of strategies aimed at preventing contact allergies and other harmful immune responses.

Impaired contact hypersensitivity in macrophage migration inhibitory factor-deficient mice

To determine whether macrophage migration inhibitory factor (MIF) is required for contact hypersensitivity (CHS) response, MIF-deficient (MIF KO) and wild-type (WT) mice were sensitized with trinitrochlorobenzene (TNCB) or oxazolone on their abdominal skin and challenged on the dorsum skin of one ear 5 days later. Significant ear swelling was observed in the WT mice, but this response was inhibited in the MIF KO mice (p<0.01 for MIF KO vs. WT mice in 24 h). In addition, lymph node cells from hapten-sensitized MIF KO mice showed a decreased capacity for transferring the CHS response. A topical application of TNCB (200 microg) caused a significant decline in epidermal Langerhans cell (LC) density (20.3%; p<0.01 compared with vehicle) 4 h after application in WT mice, but it failed to provoke a significant epidermal LC migration in MIF KO mice (7.4%). By mixed lymphocyte reaction, the T cell proliferative response to alloantigen was significantly decreased in the MIF KO mice compared with WT mice (p<0.005). Taken together, these results indicate that MIF is pivotal in the regulation of cutaneous immune responses and plays a central role in LC migration and T cell proliferation for the CHS response.

Effects of metronidazole and tinidazole ointments on models for inflammatory dermatitis in mice

We investigated the effects of 1-4% ointments of metronidazole and tinidazole (derivatives of nitroimidazole) on models of inflammatory dermatitis evoked by antigen, hapten and monoclonal anti-dinitrophenol (DNP) IgE antibody in mice. Metronidazole and tinidazole ointments (1) suppressed the late-phase reaction (LPR) of biphasic ear edema in mice sensitized with ovalbumin (OA), (2) suppressed trinitrochlorobenzene-induced inflammatory dermatitis, (3) suppressed the immediate phase reactions and LPR in mice passively sensitized with anti-DNP IgE mAb, and (4) enhanced vascular permeability and the number of scratching reactions, presumably due to itching, in passively sensitized mice. These results strongly indicate that metronidazole and tinidazole 1-4% ointments possess antiinflammatory, immunosuppressive and anti-itching effects, and have the potential for clinical use in the treatment of human inflammatory skin diseases including atopic dermatitis in addition to rosacea and acne vulgaris.

Antigen-specific T cell sensitization is impaired in IL-17-deficient mice, causing suppression of allergic cellular and humoral responses

Interleukin-17 (IL-17) is a proinflammatory cytokine produced by T cells. The involvement of IL-17 in human diseases has been suspected because of its detection in sera from asthmatic patients and synovial fluids from arthritic patients. In this study, we generated IL-17-deficient mice and investigated the role of IL-17 in various disease models. We found that contact, delayed-type, and airway hypersensitivity responses, as well as T-dependent antibody production, were significantly reduced in the mutant mice, while IL-17 deficiency of donor T cells did not affect acute graft-versus-host reaction. The results suggest that impaired responses were caused by the defects of allergen-specific T cell activation. Our findings indicate that IL-17 plays an important role in activating T cells in allergen-specific T cell-mediated immune responses.

CD4 T lymphocytes cause hepatocyte apoptosis by releasing Th1 cytokines in cellular immunological liver injury

OBJECTIVE AND DESIGN

To investigate how lymphocytes induce hepatocyte apoptosis.

MATERIALS AND METHODS

Liver injury was elicited by the trinitrobenzenesulfonic acid (TNBS) in picryl chloride (PCI)-sensitized mice. An ear swelling was also triggered with TNBS to confirm its eliciting ability. An in vitro assay for inducing hepatocyte apoptosis was established.

RESULTS

TNBS significantly elicited liver injury as well as ear swelling in PCl-sensitized mice. In the liver injury, hepatocyte apoptosis was detected 6 h after TNBS treatment. Cyclosporin A inhibited both ear swelling and hepatocyte apoptosis. When spleen cells from PCl-sensitized mice were co-cultured for 24 h with those from normal mice that had been treated with TNBS for 20 min, the supernatant collected showed a strong apoptosis-inducing activity for hepatocytes. The apoptosis was significantly reduced when the spleen cells from PCl-sensitized mice were treated previously with anti-CD3 or anti-CD4 antibody. By treating the cells, galactosamine and cycloheximide also lowered the apoptosis-inducing activity and decreased TNF-alpha and IL-2 productions. However, galactosamine treatment of hepatocytes greatly facilitated their susceptibility to supernatant-induced apoptosis. By contrast, cycloheximide completely blocked the facilitation.

CONCLUSIONS

CD4+ T cells in mice with liver injury may cause hepatocyte apoptosis by releasing cytokines including TNF-alpha and IL-2.

Soluble proteins and haptens on bone marrow-derived dendritic cells are presented to host CD4 T cells in an MHC-restricted manner

Because of their potent antigen-presenting capacity, dendritic cells (DC) have been used extensively in immunotherapy protocols. Our purpose was to functionally characterize mouse bone marrow-derived DC (BMDC) in vitro (in protein antigen- and hapten-specific assays) and in vivo (injecting soluble protein- and hapten-pulsed DC) to determine their suitability for the generation of T(h) cell responses. Furthermore, we determined whether there is cross-presentation on MHC class II molecules during in vivo protein and hapten sensitization. Co-culture of protein-pulsed [with hen egg lysozyme (HEL) or with pigeon cytochrome c (CYT)] DC with T cells from HEL- or CYT- sensitized mice induced antigen-specific T cell proliferation, but compared to cultured Langerhans cells (LC), BMDC required higher protein antigen-pulsing concentrations (100 microg and 1 mg/ml). In contrast, at low protein concentrations (10 microg/ml), BMDC stimulated an HEL-specific hybridoma very efficiently. Using an in vitro T cell proliferation assay and in vivo delayed-type hypersensitivity and contact sensitivity assays, we found that protein- and hapten-pulsed BMDC were able to sensitize syngeneic but not allogeneic hosts. Furthermore, if we injected BALB/c- and C57BL/6-derived HEL-pulsed BMDC into F1 mice, specific secondary proliferation of primed T cells occurred only when antigen-pulsed stimulator cells syngeneic to the injected BMDC were used. Using this model system we found that soluble proteins and haptens are presented by injected BMDC to host T cells in an MHC-restricted manner in vivo.

IL-1 alpha, but not IL-1 beta, is required for contact-allergen-specific T cell activation during the sensitization phase in contact hypersensitivity

Contact hypersensitivity (CHS) is a T cell-mediated cellular immune response caused by epicutaneous exposure to contact allergens. In this reaction, after the first epicutaneous allergen sensitization, Langerhans cells (LC) catch allergens and migrate from the skin to draining lymph nodes (LN) and activate naive T cells. Although IL-1 is suggested to be involved in these processes, the mechanisms have not been elucidated completely. In this report, to elucidate roles of IL-1alpha and IL-1beta in CHS, we analyzed ear swelling in 2,4,6-trinitrochlorobenzene (TNCB)-induced CHS using gene-targeted mice. We found that ear swelling was suppressed in IL-1alpha-deficient (IL-1alpha(-/-)) mice but not in IL-1beta(-/-) mice. LC migration from the skin into LN was delayed in both IL-1alpha(-/-) and IL-1beta(-/-) mice, suggesting that this defect was not the direct cause for the reduced CHS in these mice. However, we found that the proliferative response of trinitrophenyl (TNP)-specific T cells after sensitization with TNCB was specifically reduced in IL-1alpha(-/-) mice. Furthermore, adoptive transfer of TNP-conjugated IL-1-deficient epidermal cells (EC) into wild-type mice indicated that only IL-1alpha, but not IL-1beta, produced by antigen-presenting cells in EC could prime allergen-specific T cells. These observations indicate that IL-1alpha, but not IL-1beta, plays a crucial role in TNCB-induced CHS by sensitizing TNP-specific T cells.

Topical tacrolimus and cyclosporin A differentially inhibit early and late effector phases of cutaneous delayed-type and immunoglobulin E hypersensitivity

Systemic and topical administration routes of tacrolimus and cyclosporin A (CsA) were compared in effects on early and late phases of elicited T-cell-mediated contact sensitivity (CS), and effects on early and late phases of cutaneous immunoglobulin E (IgE) antibody-mediated hypersensitivity responses in mice. Thus, both CS and IgE responses in the skin have an early mast-cell-dependent phase, and also a late inflammatory phase. We measured the effects of both immunosuppressants on both phases of the respective T cell versus IgE responses. Systemic administration of both agents completely suppressed CS and IgE late-phase responses, but failed to affect either early phase. In contrast, when topical CsA was used, low doses abolished the early phase of IgE responses, but even high doses did not inhibit the early phase of CS. Conversely, topical tacrolimus inhibited the early phase of CS more potently than the early phase of cutaneous IgE hypersensitivity responses. Thus, topical treatment was needed to inhibit the early phases and the two agents acted differentially, suggesting differing susceptibility of the early phases, that are probably due to different signalling mechanisms. These studies underscore the potential value of topical administration of these powerful immunosuppressive agents in the treatment of allergic diseases that exhibit features of early-phase mast-cell-dependent inflammation, and late inflammation due to mast cells or to T cells, such as atopic dermatitis or asthma, since the early phase is predominantly susceptible to topical application, while the last phase of both IgE and T-cell inflammation responds to systemic treatment with both agents.

Dietary eicosapentaenoic acid prevents systemic immunosuppression in mice induced by UVB radiation

Moison, R. M. W. and Beijersbergen van Henegouwen, G. M. J. Dietary Eicosapentaenoic Acid Prevents Systemic Immunosuppression in Mice Induced by UVB Radiation. Radiat. Res. 156, 36-44 (2001). Reactive oxygen species (ROS) contribute to the immunosuppression induced by UVB radiation. Omega-3 fatty acids in fish oil, e.g. eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), can modulate immunoresponsiveness, but because of their susceptibility to ROS-induced damage, they can also challenge the epidermal antioxidant defense system. The influence of dietary supplementation with different omega-3 fatty acids on systemic immunosuppression induced in mice by UVB radiation was studied using the contact hypersensitivity response to trinitrochlorobenzene. In an attempt to study the mechanisms involved, UVB-radiation-induced changes in epidermal antioxidant status were also studied. Mice received high-fat (25% w/w) diets enriched with either oleic acid (control diet), EPA, DHA, or EPA + DHA (MaxEPA). Immunosuppression induced by UVB radiation was 53% in mice fed the oleic acid diet and 69% in mice fed the DHA diet. In contrast, immunosuppression was only 4% and 24% in mice fed the EPA and MaxEPA diets, respectively. Increased lipid peroxidation and decreased vitamin E levels (P < 0.05) were found in unirradiated mice fed the MaxEPA and DHA diets. For all diets, exposure to UVB radiation increased lipid peroxidation (P < 0.05), but levels of glutathione (P < 0.05) and vitamin C (P > 0.05) decreased only in the mice given fish oil. UVB irradiation did not influence vitamin E levels. In conclusion, dietary EPA, but not DHA, protects against UVB-radiation-induced immunosuppression in mice. The degree of protection appears to be related to the amount of EPA incorporated and the ability of the epidermis to maintain an adequate antioxidant level after irradiation.

Hapten-specific tolerance induced by acute, low-dose ultraviolet B radiation of skin requires mast cell degranulation

The deleterious effects of ultraviolet B radiation (UVR) on cutaneous immunity are mediated in part by cytokines released from cutaneous cells following radiation exposure. On the one hand, TNF-alpha has been advocated as the primary mediator of failed contact hypersensitivity induction, and, on the other hand, IL-10 has been held responsible for tolerance. While keratinocytes exposed to UVR have been found to produce both TNF-alpha and IL-10, there is reason to question whether these major cellular constituents of the epidermis are the relevant source of immunomodulatory cytokines after UVR. Dermal mast cells also produce TNF-alpha and IL-10, and we have recently reported that mast cell-derived TNF-alpha is required for UVR-induced impairment of CH induction. In this study, we have examined whether mast cells are also a relevant source of IL-10 in UVR-dependent tolerance. We found that (a) UVR fails to induce tolerance in mast cell-deficient mice, and (b) that tolerance occurs if mast cells are triggered to degranulate after ligation of the IgE receptor. Both types of tolerance were neutralized with anti-IL-10 antibodies, are hapten specific, and are associated with regulatory lymphoid cells. We conclude that mast cells are required in UVR-induced tolerance and may be one of the major sources of IL-10 that mediates the tolerance induced by acute, low-dose UVR.

Reversal of established delayed type hypersensitivity reactions following therapy with IL-4 or antigen-specific Th2 cells

Delayed-type hypersensitivity reactions (DTHR) are mediated by IFN-gamma-producing CD4+ (Th1) or CD8+ T cells (Tc1) and can be prevented by steering T cells toward an IL-4-producing Th2 or Tc2 phenotype. It is currently accepted that T cells can be directed toward a Th2 or Tc2 phenotype only during the initiation of an immune response. Once established, the cytokine pattern of immune reactions is believed to be stable. Therefore, inhibition of DTHR by the induction of Th2/Tc2 responses, termed immune deviation, is considered only as a prevention but not as a therapy of harmful DTHR. Here we demonstrate that therapeutic immune deviation can reverse established contact hypersensitivity (CHS), a Th1/Tc1-mediated DTHR. One or two weeks after induction of CHS, mice received either a single cycle of IL-4 therapy or adoptive transfer of antigen-specific Th2 cells. This treatment generated a novel state of immunity that provided long-lasting protection against tissue destruction and neutrophil recruitment during subsequent antigen exposures. Therapeutic immune deviation of established CHS was dependent on CD4+ T cells and the induction of endogenous IL-4 synthesis. Thus, a population of immunoregulatory Th2 cells persists during advanced inflammatory responses that can be used for therapeutic deviation of established DTHR.

Acquisition of immune function during the development of the Langerhans cell network in neonatal mice

The immunological function of the Langerhans cell (LC) network in neonatal skin was examined by defining the development of cutaneous immunity relative to the structure, phenotype and function of the epidermal LC network in neonatal, juvenile and adult mice. Analysis of epidermal sheets showed the presence of major histocompatibility complex (MHC) II+, multilectin receptor DEC-205- cells within the epidermis of 3-day-old mice; both cell density and DEC-205 expression increased until day 14. When visualized with antibodies directed at MHC II, the network was poorly formed in 3- and 7-day-old mice, as there was a lower cell density and poor MHC II expression on dendritic processes, compared to mice at day14. Application of a fluorescent antigen to 3-day-old mice revealed that the LC were inefficient in transporting antigen to the draining lymph node. There was an improvement at day 7 and by day 14 comparable numbers of antigen carrying cells were detected in the lymph nodes of 6-week-old mice. The reduced antigen carriage in 3- and 7-day-old mice correlated with a poor contact sensitivity response. This was not simply due to failure to present antigen, but development of immunosuppression, as transfer of T cells from adult mice that were previously treated with antigen when they were 3 days old, to adult recipients resulted in antigen specific immunosuppression. Analysis of CD80 and CD86 expression showed that LC from day 3 skin expressed CD80, but not CD86 and application of antigen through this skin was inefficient in upregulating CD86. These findings indicate that when the neonatal LC network is poorly developed it is functionally immature and antigen applied through this 'functionally immature network' results in antigen specific immunosuppression.

Prevention of autoimmunity by induction of cutaneous tolerance

Autoimmune gastritis develops in 20-60% of BALB/c mice following thymectomy at 3 days after birth (3dnTx). Previously we identified the gastric H+/K+ ATPase as the causative autoantigen and mapped the immunoreactive T cell epitope to a carboxyl-terminal peptide on the gastric H+/K+ ATPase beta subunit. Here we show that autoimmune gastritis can be suppressed by immunizing 3dnTx mice through neonatal skin with the beta subunit peptide, in combination with the contact sensitizer TNCB. When spleen cells were transferred from suppressed mice to nude mice a proportion of recipient mice developed gastritis. These results indicate that pathogenic T cells were still present in the 3dnTx mice but the absence of gastritis indicates that their activity can be regulated following induction of cutaneous tolerance by immunizing through neonatal skin. We propose that cutaneous tolerance is induced through mediation of immature Langerhans cells in neonatal skin and that this tolerance prevented the autoreactivity of pathogenic T cells. This procedure will have implications for strategies to suppress autoimmunity.

UV exposure alters respiratory allergic responses in mice

We have tested the hypothesis that exposure to ultraviolet light would inhibit T helper-1 (Th1) responses and stimulate T helper-2 (Th2) responses, and that thus in a mouse model of allergic (i.e. extrinsic) asthma (using ovalbumin [OVA] as the allergen) increased symptoms would be observed, while in a model of Th1-dependent occupational asthma (in which picryl chloride is the allergen) decreased symptoms would be observed. Whereas reduced interferon (IFN)-gamma production, decreased inflammatory responses in the airways, and reduced airway reactivity to nonspecific stimuli were observed in UV-preexposed picryl chloride sensitized and challenged mice, the results in the OVA model were less clear. Increased interleukin (IL)-10 production as a result of UV exposure was observed, together with unchanged IL-4 and IFN-gamma. In addition, decreased OVA-specific immunoglobin, IgG1 and IgE, titers were noted, as well as decreased nonspecific airway hyperreactivity. Eosinophilic inflammatory responses were not influenced. The results indicate that UV exposure can have systemic effects that influence ongoing immune responses in the respiratory tract. The effects are not only restricted to immune responses that are predominantly Th1 dependent (i.e. pulmonary delayed-type hypersensitivity and IFN-gamma production in response to picryl chloride) but also to immune response that are predominantly Th2 dependent, i.e. decreased specific IgE titers.

Transcription-coupled and global genome repair differentially influence UV-B-induced acute skin effects and systemic immunosuppression

Exposure to UV-B radiation impairs immune responses in mammals by inhibiting especially Th1-mediated contact hypersensitivity and delayed-type hypersensitivity. Immunomodulation is not restricted to the exposed skin, but is also observed at distant sites, indicating the existence of mediating factors such as products from exposed skin cells or photoactivated factors present in the superficial layers. DNA damage appears to play a key role, because enhanced nucleotide excision repair (NER) strongly counteracts immunosuppression. To determine the effects of the type and genomic location of UV-induced DNA damage on immunosuppression and acute skin reactions (edema and erythema) four congenic mouse strains carrying different defects in NER were compared: CSB and XPC mice lacking transcription-coupled or global genome NER, respectively, as well as XPA and TTD/XPD mice carrying complete or partial defects in both NER subpathways, respectively. The major conclusions are that 1) transcription-coupled DNA repair is the dominant determinant in protection against acute skin effects; 2) systemic immunomodulation is only affected when both NER subpathways are compromised; and 3) sunburn is not related to UV-B-induced immunosuppression.

Signal transducer and activator of transcription 6 is essential in the induction of contact hypersensitivity

Contact hypersensitivity (CHS) is thought to be mainly associated with the activation of T helper type 1 (Th1) cells. However, there is also evidence that Th2 cells or Th2 cytokines play a role in the development of CHS. To analyze the functional contribution of Th2 cytokines interleukin (IL)-4 and IL-13, signal transducer and activator of transcription 6 (STAT6)-deficient (STAT6(-/)-) and wild-type (wt) control C57BL/6 mice were contact sensitized with 5% 2,4,6-trinitrochlorobenzene (TNCB), 0.5% 2,4-dinitrofluorobenzene, or 5% 4-ethoxyl methylene-2-phenyl-2-oxazolin-5-one, and any skin reactions were examined. Ear swelling was significantly reduced with a delayed peak response in STAT6(-/)- mice compared with wt mice.A histological analysis revealed that the infiltration of both eosinophils and neutrophils in the skin challenged after 24 h in STAT6(-/)- mice decreased substantially compared with that in wt mice. The expression of Th2 cytokines (IL-4, IL-5) in TNCB-challenged skin tissues and the supernatants from T cells stimulated by 2,4,6-trinitrobenzene sulfonate-modified spleen cells, as well as the immunoglobulin (Ig)E and IgG1 response after challenge, were also profoundly reduced in STAT6(-/)- mice, whereas the expression of interferon gamma was the same in STAT6(-/)- and wt mice after challenge. Furthermore, adoptive transfer experiments revealed that STAT6(-/)- mice induced CHS after injection of lymph node cells obtained from sensitized wt mice. Our data suggest that the STAT6 signal plays a critical role in the induction phase of CHS.

Ultraviolet B-induced suppression of immune responses in interleukin-4-/- mice: relationship to dermal mast cells

Ultraviolet B radiation is immunosuppressive by multiple mechanisms. In interleukin-4-/- mice, ultraviolet B radiation was not able to suppress delayed-type hypersensitivity or contact hypersensitivity responses when the sensitizing antigen was applied to nonirradiated sites. In contrast, ultraviolet B significantly suppressed contact hypersensitivity responses to haptens applied to irradiated sites in interleukin-4-/- mice. In mast cell depleted Wf/Wf mice, ultraviolet B radiation also significantly suppressed contact hypersensitivity responses to sensitizing antigens applied to irradiated but not to unirradiated sites. In both interleukin-4-/- mice and Wf/Wf mice, the mast cell product, histamine, was immunosuppressive implicating mast cells as the dysfunctional cell in interleukin-4-/- mice. The prevalence of dermal mast cells was similar in wild-type and interleukin-4-/- mice. Dermal mast cells of interleukin-4-/- mice, however, express very low levels of c-kit and did not significantly degranulate in response to ultraviolet B. Ultraviolet radiation induced significant and similar levels of serum interleukin-10 in wild-type and interleukin-4-/- mice. We conclude that interleukin-4 indirectly affects ultraviolet B suppression of contact hypersensitivity and delayed-type hypersensitivity responses to sensitizing antigens applied at sites other than those irradiated by providing a critical differentiative signal for dermal mast cells. This study further emphasizes the central role of mast cells in the initial processes by which ultraviolet B radiation is immunomodulatory for immune responses to sensitizing antigens applied to nonirradiated sites.

IL-12 is produced by antigen-presenting cells stimulated with soluble alphabeta TCR and restores impaired T(h)1 responses

Contact sensitivity (CS) is a cutaneous T(h)1 response that is induced by skin painting with reactive hapten. In prior in vivo studies of CS, we showed that recombinant soluble alphabetaTCR (sTCR) acted non-specifically to protect CS-effector T cells from suppression, but no molecular mechanism was determined. In the current study, we employed an in vitro system to investigate the mechanism of how sTCR protect CS-effector T cells from suppression. Immune CS-effector cells and appropriate hapten-conjugated antigen-presenting cells (APC) were incubated together with down-regulatory culture supernatant produced by suppressive spleen cells from mice tolerized i.v. with specific hapten, which produced strong inhibition of IFN-gamma production by the CS-effector cells. Importantly, addition of two different sTCR, of unrelated specificity, reversed this down-regulation and thus restored IFN-gamma production. We found that the APC, and not the CS-effector T cells, were the locus of the sTCR-mediated protection and showed direct binding of sTCR to APC by flow cytometry. Further, addition of anti-IL-12 showed that sTCR protection was due to IL-12 induced by sTCR and released by the APC, and was confirmed by ELISA measurement of IL-12 induced in APC supernatants by sTCR incubation. These results indicated a possible new regulatory loop in which suppression was reversed by IL-12 derived from APC, following direct surface binding of sTCR, and enhanced by IFN-gamma production from the T(h)1 CS-effector cells.

Signals involved in the early TH1/TH2 polarization of an immune response depending on the type of antigen

BACKGROUND

The early production of distinct cytokines by epidermal cells (ECs) in response to antigen exposure may govern the development of TH1 -like immune responses, such as contact sensitivity, or TH2 -like immune responses, such as IgE-dependent allergies of the immediate type, depending on the type of antigen.

OBJECTIVE

The aim of this study was to compare the signals induced by protein allergens with those induced by haptens in ECs and subsequently in local draining lymph node cells (LNCs) or splenocytes.

METHODS

BALB/c mice were primed in vivo with the protein allergens ovalbumin or birch pollen or the haptens 2, 4-dinitrofluorobenzene or trinitrochlorbenzene, respectively, and cytokine and immunoglobulin secretions of responding splenocytes were measured by ELISA after in vitro coculture with ECs. Induction of cytokine mRNA expression in ECs and LNCs was analyzed by reverse transcriptase-PCR.

RESULTS

In the presence of protein allergens, ECs enhance the induction of a TH2 immune response (IL-4 and IgE production of splenocytes), whereas a TH1 immune response (IFN-gamma and IgG2a production) was only induced in the context of haptens. Heat inactivation of ovalbumin did not diminish the development of a TH2 immune response. One direct effect of antigen on ECs was the earlier expression of IL-10 mRNA after stimulation with protein allergens (30 minutes) than with haptens (2 hours) in vitro. By using an in vivo approach, sensitization of the skin with trinitrochlorbenzene, but not with ovalbumin, resulted in an early induction of IL-1beta, IL-12p40, and IFN-gamma mRNA in LNCs, whereas IL-18 was induced by both.

CONCLUSION

These data indicate that the type of antigen strongly influences the type of immune response by eliciting distinct signals already in the epithelium.

Comparison of immunopharmacological actions of 8 kinds of kampo-hozais clinically used in atopic dermatitis on delayed-type hypersensitivity in mice

We studied here the effects of 8 kinds of kampo-hozais clinically used to treat atopic dermatitis (Shofu-san, Toki-inshi, Unsei-in, Oren-gedoku-to, Ji-zuso-ippo, Jumi-haidoku-to, Juzen-taiho-to, Hochu-ekki-to) on delayed-type hypersensitivity (DTH), using three types of murine models such as picryl chloride (PC)-induced (contact hypersensitivity), sheep red blood cell (SRBC)-induced (Jones-Mote's reaction) and tuberculin-induced DTH response, in order to clarify and to compare the immunopharmacological action of kampo-hozais. Most of the kampo-hozais investigated here suppressed PC-induced contact hypersensitivity, especially at the inductive phase. Comparing the efficacies of these kampo-hozais on the three types of DTH responses in mice, they were generally divided into 4 groups. Shofu-san significantly reduced PC-induced and tuberculin-induced DTH responses but not a SRBC-induced DTH response. On the other hand, Toki-inshi reduced contact hypersensitivity, tuberculin type DTH response and Jones-Mote's reaction. Ji-zuso-ippo and Juzen-taiho-to suppressed mainly Jones-Mote's reaction, and Unsei-in, Oren-gedoku-to and Jumi-haidoku-to intensively suppressed contact hypersensitivity. We thought that these findings could help us understand how to use these kampo-hozais properly.

Induction of peripheral tolerance in neonatally thymectomized mice by immunization through chemical carcinogen-altered skin

BALB/c mice thymectomized 3 days after birth (3dnTx) are prone to the development of autoimmune gastritis. As this outcome may be a consequence of altered immunoregulatory mechanisms, we set out to determine the immunological status of these mice and their capacity to acquire antigen-specific peripheral tolerance. The latter was assessed by the capacity of these mice to suppress a contact sensitivity response to 2,4,6-trinitrochlorobenzene (TNCB) following treatment of the skin by the carcinogen, DMBA. The 3dnTx mice had a reduced number of CD4(+) and CD8(+) T cells and a reduced lymphocyte proliferative response to PHA, but a normal contact sensitivity response to TNCB. After treatment of the skin with DMBA these mice failed to develop contact sensitivity to TNCB. Adoptive transfer of splenocytes from these mice to naive mice transfered antigen-specific suppression, irrespective of whether the 3dnTx mice had developed autoimmune gastritis. We conclude that despite thymectomy at day 3 and the attendant immunosuppression, the capacity of BALB/c mice to generate antigen-specific peripheral tolerance to TNCB was retained. These results suggest that precursor T cells which mediate suppression to antigens such as TNCB are present in 3dnTx mice and that these cells are likely to have developed in the thymus and exported to the periphery before 3 days after birth.

Role of CD4+ and CD8+ T cells in regulating the chronic development of liver injury induced by delayed-type hypersensitivity to picryl chloride

In this study we first investigated the cellular immune responses in mice with chronic liver injury induced by delayed-type hypersensitivity to picryl chloride (PCl). A continuous reduction, after week 3 of liver injury, was observed in the level of PCl-induced contact sensitivity but not in sheep red blood cell-induced footpad reaction, suggesting the presence of PCl-specific suppression. When spleen cells from mice whose liver had been injured for 1 week were systemically transferred into syngeneic recipients with the liver injury, the elevation in serum lactic dehydrogenase and the decrease in alkaline phosphatase and albumin levels in recipient mice were significantly exacerbated. However, when the liver damage in the donor mouse was allowed to proceed for 3, 5 or 7 weeks, biochemical changes in recipients were reduced to near normal levels. A flow-cytometric assay demonstrated that the number of CD4+ T cells in both spleen cells and liver nonparenchymal cells decreased dramatically during the late phase of liver injury, while CD8+ counts did not. These findings suggest that CD4+ and CD8+ T lymphocytes may contribute to the positive and negative regulation, respectively, of the early and late phases in the chronic development of liver injury.

Cross-talk between V beta 8+ and gamma delta+ T lymphocytes in contact sensitivity

We have previously reported that T lymphocytes proliferating in vitro to the hapten trinitrochlorobenzene (TNCB) exhibit a very restricted V beta gene usage and response to TNCB is limited to T-cell receptors (TCR) composed of V beta 8.2 in combination with V alpha 3.2, V alpha 8 and V alpha 10. This paper investigates the role played by T lymphocytes expressing the V beta 8.2 gene segment in the contact sensitivity (CS) reaction to TNCB in the intact mouse and in its passive transfer into naive recipient mice. Mice injected with monoclonal antibodies to V beta 8 are unable to develop CS upon immunization with TNCB and 4-day TNCB-immune lymph node cells from mice that had been depleted in vivo or in vitro of V beta 8+ T lymphocytes fail to transfer CS. However, when separated V beta 8+ and V beta 8- cells were used for passive transfer, it was found that V beta 8+ T lymphocytes failed to transfer CS when given alone to recipient mice and a V beta 8- population was absolutely required. Further analysis revealed that within the V beta 8- population, T lymphocytes expressing the gamma delta TCR were fundamental to allow transfer of the CS reaction. These gamma delta cells were found to be antigen non-specific, genetically unrestricted and to rearrange the V gamma 3 gene segment. This indicates that transfer of the CS reaction requires cross-talk between V beta 8+ and gamma delta+ T lymphocytes, thus confirming our previous results obtained using TNCB-specific T-cell lines. Time-course experiments showed that V beta 8+ lymphocytes taken 4-24 days after immunization with TNCB were able to proliferate and produce interleukin-2 (IL-2) in response to the specific antigen in vitro. Similar time-course experiments were then undertaken using the passive transfer of the CS reaction system. The results obtained confirm that TNCB-specific V beta 8+ T lymphocytes are present in the lymph nodes of immunized mice from day 4 to day 24, and reveal that gamma delta+ T lymphocytes are active for a very short period of time, i.e. days 4 and 5 after immunization. In fact, TNCB-specific V beta 8+ cells are able to transfer CS when taken 4-24 days after immunization, providing the accompanying V beta 8- or gamma delta+ T lymphocyte are obtained 4 days after immunization. In contrast, injection of V beta 8+ T lymphocytes together with V beta 8- or gamma delta+ T lymphocytes that had been taken 2 or 6 days after immunization, failed to transfer significant CS into recipient mice. Taken together, our results confirm that cross-talk between V beta 8+ and gamma delta+ T lymphocytes is necessary for full development of the CS reaction and may explain why the CS reaction in the intact mouse lasts up to 21 days after immunization while the ability of immune lymph node cells to transfer CS is limited to days 4 and 5 after immunization.

Entry into afferent lymphatics and maturation in situ of migrating murine cutaneous dendritic cells

An important property of dendritic cells (DC), which contributes crucially to their strong immunogenic function, is their capacity to migrate from sites of antigen capture to the draining lymphoid organs. Here we studied in detail the migratory pathway and the differentiation of DC during migration in a skin organ culture model and, for comparison, in the conventional contact hypersensitivity system. We report several observations on the capacity of cutaneous DC to migrate in mouse ear skin. (i) Upon application of contact allergens in vivo the density of Langerhans cells in epidermal sheets decreased, as determined by immunostaining for major histocompatibility complex class II, ADPase, F4/80, CD11b, CD32, NLDC-145/DEC-205, and the cytoskeleton protein vimentin. Evaluation was performed by computer assisted morphometry. (ii) Chemically related nonsensitizing or tolerizing compounds left the density of Langerhans cells unchanged. (iii) Immunohistochemical double-staining of dermal sheets from skin organ cultures for major histocompatibility complex class II and CD54 excluded blood vessels as a cutaneous pathway of DC migration. (iv) Electron microscopy of organ cultures revealed dermal accumulations of DC (including Birbeck granule containing Langerhans cells) within typical lymphatic vessels. (v) Populations of migrating DC in organ cultures upregulated markers of maturity (the antigen recognized by monoclonal antibody 2A1, CD86), but retained indicators of immaturity (invariant chain, residual antigen processing function). These data provide additional evidence that during both the induction of contact hypersensitivity and in skin organ culture, Langerhans cells physically leave the epidermis. Both Langerhans cells and dermal DC enter lymphatic vessels. DC mature while they migrate through the skin.

Development of hapten-induced IL-4-producing CD4+ T lymphocytes requires early IL-4 production by alphabeta T lymphocytes carrying invariant V(alpha)14 TCR alpha chains

This paper investigates the mechanisms responsible for the generation of IL-4-producing CD4+ T cells during contact sensitization with the hapten trinitrochlorobenzene (TNCB). Lymph node cells taken 1 day after immunization spontaneously released IL-4 while lymph node cells taken 2 and 3 days after immunization did not produce IL-4. A second wave of IL-4 production that was both antigen-specific and MHC class II (I-A)-restricted was observed 4 days after immunization. The spontaneous release of IL-4 at day 1 was due to the alphabeta+ double-negative (CD4- CD8-) T lymphocytes that also expressed NK1.1 and showed V(alpha)14 rearrangement, while alphabeta+ CD4+ T lymphocytes were the source of the antigen-specific IL-4 production at day 4. Early IL-4 production was required for the development of IL-4-producing CD4+ T cells as mice injected with anti-V(alpha)14 or anti-IL-4 mAb produced little IL-4 and IL-10, while production of IFN-gamma was increased approximately 2-fold. These results indicate that the development of IL-4-producing CD4+ T lymphocytes in the TNCB system requires early production of IL-4 by alphabeta+ double-negative cells carrying invariant V(alpha)14 TCR alpha chain.

Percutaneous sensitization with allergens through barrier-disrupted skin elicits a Th2-dominant cytokine response

We investigated whether percutaneous sensitization with different allergens through barrier-disrupted skin regulates the balance of Th1/Th2 cytokine expression. When mice were sensitized with the typical hapten picryl chloride (PiCl) by a single topical application to intact skin, there was an up-regulation in the lymph nodes (LN) of mRNA expression for the Th1 cytokines IL-2 or IFN-gamma, and for the Th2 cytokine IL-4. In contrast, sensitization with PiCl after barrier disruption of the skin down-regulated the expression of mRNA for IFN-gamma in a tape-stripping number-dependent manner without changing the expression of mRNA for IL-4. When mice were sensitized with house dust mite antigens (MA) by a single topical application to barrier-disrupted abdominal skin, there was a tape-stripping number-dependent up-regulation in the LN of mRNA expression for IL-4 but not for IL-2 or IFN-gamma. In the LN, mRNA for the IL-4-inducible immunoglobulins IgE and IgG1, but not for the IFN-gamma-inducible IgG2a, were up-regulated after sensitization with MA, while all three immunoglobulin mRNA were augmented after PiCl sensitization through intact skin. Antigenic elicitation by a topical application of PiCl in aural skin of mice sensitized through intact skin consistently increased the expression of mRNA for all three cytokines in the challenged skin, whereas elicitation in mice sensitized through barrier-disrupted skin decreased the expression of mRNA for IL-2 and IFN-gamma, but not for IL-4. Antigenic elicitation by subcutaneous injection of MA in aural skin consistently increased the expression of mRNA for IL-4, but not for IL-2 or IFN-gamma in the challenged skin. Infiltration of eosinophils in the dermis was more prominent following elicitation with MA in mice sensitized through barrier disruption than with PiCl in mice sensitized through intact skin. These findings suggest that the percutaneous entry of environmental allergens through barrier-disrupted skin is strongly associated with the induction of Th2-dominant immunological responses, as is seen in atopic dermatitis.

Repeated elicitation of contact hypersensitivity induces a shift in cutaneous cytokine milieu from a T helper cell type 1 to a T helper cell type 2 profile

We previously demonstrated that repeated application of 2,4,6-trinitro-1-chlorobenzene resulted in a site-restricted shift in the time course of Ag-specific hypersensitivity responses from a typical delayed-type to an early-type response. Here we demonstrated that the cutaneous microenvironment at the time of Ag presentation to T cells in the elicitation, but not the induction, phase of contact hypersensitivity is responsible for the shift. To investigate the differences in the cutaneous cytokine milieu between the acute and chronic phases of contact hypersensitivity, sequential cytokine dynamics after 2,4,6-trinitro-1-chlorobenzene application were assessed in the acute vs chronic lesions. In the acute lesions, increased mRNA levels for IFN-gamma and IL-2 were rapidly detected at 1 h and remained elevated at 12 h, while mRNA expression for IL-4 and IL-10 was minimally up-regulated between approximately 12 and 24 h. In chronic lesions, high levels of constitutive expression of IL-4 mRNA were observed and IL-10 mRNA was dramatically up-regulated at 1 approximately 3 h in an Ag-specific fashion, whereas the expression of Th1-type cytokines was markedly reduced. Increased mRNA levels for Th2-type cytokines in the chronic lesions was also reflected at the protein level. These results indicate that repeated elicitation with Ag alters the balance of cytokines released locally, with a shift toward Th2-dominated responses, which would represent the natural evolution processes directed toward reducing a more deleterious Th1 response.

Histamine involvement in UVB- and cis-urocanic acid-induced systemic suppression of contact hypersensitivity responses

Studies in experimental models have implicated histamine and prostanoids in ultra-violet B (UVB)- and cis-urocanic acid (UCA)-induced systemic immunosuppression. This study examined the hypothesis that UVB irradiation and cis-UCA suppressed contact hypersensitivity responses to hapten by induction of histamine, which in turn evoked a prostanoid-dependent component of immunosuppression. BALB/c mice were administered with a cis-UCA monoclonal antibody, a combination of histamine types 1 and 2 receptor antagonists, or indomethacin. Mice were sensitized to 2,4,6-trinitrochlorobenzene (TNCB) on their ventral surface 5 days after UVB irradiation, or cis-UCA or histamine administration. Ears were challenged with TNCB 5 days later. Cis-UCA antibody inhibited the suppressive effects of UVB by approximately 60% and confirmed that suppression of contact hypersensitivity responses by UVB was due, at least in part, to mechanisms involving cis-UCA. Histamine suppressed contact hypersensitivity responses and the effects of cis-UCA and histamine were not cumulative, suggesting that cis-UCA and histamine signal largely through the same pathway. The immunosuppressive effects of histamine were not affected by the cis-UCA antibody, consistent with the model that histamine acts downstream of cis-UCA. Administration of histamine receptor antagonists and indomethacin each approximately halved the UVB- and cis-UCA-induced systemic suppression of contact hypersensitivity responses. The effects of the reagents that inhibited the action of histamine and prevented prostanoid production were not cumulative, and suggested involvement in the same pathway. These results support the involvement of cis-UCA, histamine and prostanoids, in a sequence, in UVB-induced systemic suppression of contact hypersensitivity responses.

Nonatopic asthma: in vivo airway hyperreactivity adoptively transferred to naive mice by THY-1(+) and B220(+) antigen-specific cells that lack surface expression of CD3

To investigate the cellular immune events contributing to airway hyperreactivity (AHR), we studied an in vivo mouse model induced by the hapten picryl (trinitrophenyl) chloride (PCl). Mice were immunized by cutaneous contact sensitization with PCl and airway challenged subsequently with picryl sulfonic acid (PSA) antigen (Ag). Increased airway resistance was produced late (24 h) after Ag challenge, disappeared by 48 h, and was associated with no decrease in diffusion capacity. AHR could be produced in PCl immune/ PSA challenged mice on day 7 or even, with challenge, as early as 1 d after contact sensitization, after adoptive transfer of immune cells lacking CD3(+) contact sensitivity effector T cells, or after transfer of Ag-specific lymphoid cells depleted of conventional T lymphocytes with surface determinants for CD3, CD4, CD8, TCR-beta, or TCR-delta molecules. Further experiments showed that development of AHR depended upon transfer of immune cells expressing surface membrane Thy-1 and B220 (CD45RA) determinants. We concluded that a novel population of Ag-specific lymphoid cells with a defined surface phenotype (Thy-1(+), CD3(-), CD4(-), CD8(-), TCR-alphabeta-, TCR-gammadelta-, and CD45RA+) is required in a mouse model for the development of AHR.

Enhancement of CD4+ T-cell-dependent interleukin-2 production in vitro by murine alveolar macrophages: the role of leukotriene B4

Local tissue macrophages are known to play a key role in regulation of adaptive immune responses, often by inhibition of T-cell activation and proliferation. In this study, we compare the influence of alveolar and peritoneal macrophages on T-cell-dependent interleukin-2 (IL-2) release. Alveolar macrophages, in contrast to peritoneal macrophages, enhance IL-2 release. Assay of a panel of potential macrophage-derived mediators indicated that activated alveolar macrophages stimulated greater release of IL-1 beta, tumour necrosis factor-alpha and, especially, leukotriene B4 (> 100 times) than activated peritoneal macrophages. Inhibition of prostaglandin synthesis by alveolar macrophages further enhanced the production of IL-2, while inhibition of leukotriene synthesis abolished the enhancement. The addition of exogenous prostaglandin E2 inhibited IL-2 release, while exogenous leukotriene B4 enhanced IL-2 release. When added simultaneously, the two compounds antagonized each other's activity. In conclusion, this study confirms that alveolar macrophages enhance IL-2 secretion, and suggests that this enhancement may be due at least in part to the very high rates of production of leukotriene B4. The overall influence of macrophage populations on T cells in vivo will reflect the complex balance between the multiple mediators produced within the local tissue microenvironment.

Nitric oxide production by macrophages stimulated by antigen-binding T-cell factors

Contact sensitivity to small molecular weight compounds is accompanied by the production of antigen-specific T-cell factors (TCF) shortly after skin application of the sensitizing agents. In this study, we show that macrophages can be activated by these TCF to generate large amounts of nitric oxide (NO). Incubation of the murine macrophage cell line J774 for 24 h with TCF raised against dinitrofluorobenzene (DNFB) or picryl chloride (PCL) resulted in a nitrite accumulation in the culture medium. Priming of J774 with rIFN-gamma synergistically enhanced stimulation of NO synthesis by DNFB-F and PCL-F. A possible contribution of lipopolysaccharide (LPS) as a contaminant of the TCF was excluded. The enhanced production of NO after stimulation with TCF was accompanied with an increased expression of inducible NO synthase. Inclusion of inhibitors of protein tyrosine kinase and protein kinase C inhibited the TCF-induced NO production by macrophages, indicating the involvement of both protein kinases in the signaling pathway activated by TCF. Since NO is an important biological mediator with many immunoregulatory properties, our results suggest a potential role for increased NO production by macrophages in the elicitation of contact sensitivity to small molecular weight compounds.

Down-regulation of an established immune response via chemical carcinogen or UVB-altered skin

The ability to produce antigen-specific down-regulation of an established immune response was investigated in 2,4,6-trinitrochlorobenzene (TNCB)-immune mice by delivery of antigen through chemical carcinogen- or ultraviolet B (UVB)-treated skin. When TNCB-immune mice were treated on the dorsal trunk skin with 7,12-dimethylbenz(a)anthracene (DMBA) followed by TNCB there was an antigen-specific reduction in both contact sensitivity and antibody production. Further, immune mice that received spleen cells from naive syngeneic donors treated with DMBA followed by TNCB also exhibited a reduction in both contact sensitivity and antibody production. In contrast, mice treated with UVB irradiation followed by TNCB had a reduction in contact sensitivity but not antibody production. These results provide evidence that an ongoing immune response can be manipulated by immunization through a modified skin immune system. This may provide a beneficial approach for the treatment of autoimmune disease.

Langerhans' cells produce type IV collagenase (MMP-9) following epicutaneous stimulation with haptens

For initiation of the contact hypersensitivity response, epidermal Langerhans' cells (LC) migrate from the epidermis to draining nodes via afferent lymphatics by passing through the basement membrane. In this study, we examined production of matrix metalloproteinases (MMPs) in LC-enriched epidermal cells to clarify the type of enzymes involved in LC transmigration through the basement membrane. Using gelatine enzymography and immunoblotting analysis, 95,000 MW type IV collagenase (MMP-9) was found to be produced by LC-enriched epidermal cells. Analysis of the kinetics of MMP-9 expression showed that its production was induced within 6 hr after application of 2,4,6-trinitrochlorobenzene (TNCB), substantially increased between 12 hr and 24 hr, and then decreased to the normal level by 7 to 10 days. Other haptens, such as 2,4-dinitrochlorobenzene and 2,4-dinitrofluorobenzene, also induced MMP-9 expression. Fluoroescence-activated cell sorter analysis revealed that LC were one of the major cell types to express MMP-9 in response to TNCB. In addition, highly enriched LC from sensitized skin were shown to express strong gelatinolytic activity. These results indicate that LC by themselves, as well as other epidermal cells, are capable of producing MMP-9, and suggest that MMP-9 may contribute to proteolysis associated with transmigration of LC in the induction phase of contact dermatitis.

Serum TABM produced during anterior chamber-associated immune deviation passively transfers suppression of delayed-type hypersensitivity to primed mice

Injection of soluble protein antigen into the anterior chamber of the eye of primed mice induces anterior chamber-associated immune deviation (ACAID) which is manifested by suppression of delayed-type hypersensitivity (DTH) to the antigen. Recently, we found that ACAID induced in primed mice also results in a rapid rise in serum of soluble T lymphocyte-derived proteins specific for nominal antigen (TABM). Here, we demonstrate that serum TABM induced in primed mice during ACAID will transfer the suppression of DTH to mice primed to the same antigen. Sera from TNP-BSA-primed mice that received an anterior chamber injection of TNP-BSA, but not BSA alone, suppressed the DTH response to TNP when injected into other TNP-BSA-primed mice. Sera absorbed with Sepharose beads conjugated with either anti-TCR C(alpha), anti-TCR C(beta), anti-TABM or TNP-BSA did not contain TNP-specific TABM and did not transfer suppression of DTH. These results suggest that the antigen-specific, TCR C(alphabeta)+ TABM that appear in serum during ACAID are able to confer on or amplify the capacity of sensitized T cells to suppress DTH. We believe this to be the first demonstration of an in vivo immunologic function that is specifically associated with TABM produced in vivo.

Three cell subsets are required for the transfer of delayed-type hypersensitivity reaction by antigen-specific T cell lines

Antigen (trinitrochlorobenzene)-specific T cell lines were obtained by repeated stimulation of lymph node cells from immune mice with antigen in vitro. These T cell lines, consisting of more than 90% CD4+ Vbeta8.2+ and 6 to 9% gammadelta+ T lymphocytes, transfer contact sensitivity (CS) locally when injected at the same site as the challenge antigen, but fail to mediate a systemic passive transfer when injected i.v. Injection of T cell lines together with spleen cells from mice immunized 1 day beforehand (1-day cells) allowed a successful, specific systemic transfer of CS. Phenotypic analysis showed that the 1-day immune cell was alphabeta+, gammadelta-, sIg-, CD3+, CD4-, CD8-, CD5+, B220 (CD45R)+, Thy 1.2+. The effect of 1-day immune cells occurred through a mechanism involving IL-4, as 1-day immune cells failed to allow systemic transfer of CS by T cell lines in recipient mice treated with mAb to IL-4. These observations strongly indicate that three cell subsets are required for the systemic passive transfer of CS by T cell lines: alphabeta+ CD4+, gammadelta+, and a third cell subset, which is CD45R+, alphabeta+, CD3+, but double (CD4, CD8) negative.

Modulation of picryl chloride-induced contact hypersensitivity reaction in mice by nitric oxide

We have studied the possible involvement of nitric oxide (NO) in the contact hypersensitivity reaction. A biphasic response of ear swelling was observed at 2 h (early phase) and 24 h (late phase) after application of the antigen to picryl chloride (PC1)-sensitized CBA/J mice. Intravenous injection of NO synthase inhibitor, NG-nitro-L-arginine methyl ester (L-NAME), at the time of PC1 challenge, inhibited in a concentration-dependent fashion the antigen-induced contact hypersensitivity reaction. Low-dose (1 mg/kg) L-NAME inhibited the early-phase reaction but not the late-phase reaction. High-dose (250 mg/kg) L-NAME inhibited both early- and late-phase reactions. D-NAME (enantiomer of L-NAME) did not inhibit the antigen-induced ear swelling. High-dose (250 mg/kg) L-arginine increased both early and late phase reactions. D-Arginine (enantiomer of L-arginine) did no increase the antigen-induced ear swelling. L-NAME injection, however, did not suppress phenol-induce irritant inflammation. Treatment of mice undergoing PC1-induced contact hypersensitivity reaction with L-NAME reduced the production of interleukin-2 and interferon-gamma by draining lymph node cells. Treatment with L-arginine, on the other hand increased the production of interleukin-2 and interferon-gamma. These results suggest that NO plays a modulating role in contact hypersensitivity reaction.