Regulatory T Cells Prevent Neutrophilic Infiltration of Skin during Contact Hypersensitivity Reactions by Strengthening the Endothelial Barrier.

The healing phase of contact hypersensitivity reactions is critically dependent on regulatory T cells (Tregs), but even the early inflammatory phase, that is, 6-24 hours after induction of a contact hypersensitivity reaction, is susceptible to Treg-mediated suppression. To investigate the underlying mechanisms, we injected Tregs before the challenge and analyzed the skin-infiltrating cells as early as 6 hours later. Early on, we found mainly neutrophils in the challenged skin, but only a few T cells. This influx of neutrophils was blocked by the injection of Tregs, indicating that they were able to prevent the first wave of leukocytes, which are responsible for starting an immune reaction. As an underlying mechanism, we identified that Tregs can tighten endothelial junctions by inducing intracellular cAMP, leading to protein kinase A-RhoA‒dependent signaling. This eventually reorganizes endothelial junction proteins, such as Notch3, Nectin 2, Filamin B, and VE-cadherin, all of which contribute to the tightening of the endothelial barrier. In summary, Tregs prevent the leakage of proinflammatory cells from and into the tissue, which establishes a mechanism to downregulate immune reactions.

The role of toll-like receptor 3 in chronic contact hypersensitivity induced by repeated elicitation.

BACKGROUND: Accumulating evidence suggests that Toll-like receptor (TLR)-3 signaling is involved in non-infectious immune and inflammatory reactions as well as in viral infections. The skin of patients with atopic dermatitis (AD) is often infected with virus and bacteria, leading to the aggravation of atopic symptoms. These findings suggest TLR3 signaling may be involved in the pathogenesis of AD, but the exact role of TLR3 in AD remains to be defined. OBJECTIVE: The purpose of this study was to investigate the role of TLR3 in chronic contact hypersensitivity reactions induced by repeated elicitation, resembling the features of AD. METHODS: Wild-type (WT) and Toll-like receptor 3 knockout (Tlr3 KO) mice were sensitized, and chronic contact hypersensitivity reactions were elicited in their ear skin via repeated application of a hapten, 2,4,6-trinitro-1-chlorobenzene (TNCB) or oxazolone. RESULTS: The Tlr3 KO mice exhibited less ear swelling, less leukocyte infiltration into the skin, and lower serum total IgE levels than WT mice after hapten challenge. The Tlr3 KO mice also displayed lower expression levels of inflammatory cytokines (interleukin (IL)-33, IL-4, IL-10, and interferon-ɤ in their TNCB-treated ear skin than WT mice. CONCLUSION: These results showed that TLR3 deficiency suppressed the development of chronic contact hypersensitivity reactions, suggesting that TLR3 signaling may participate in the pathogenesis of AD.

Expression of CD73 slows down migration of skin dendritic cells, affecting the sensitization phase of contact hypersensitivity reactions in mice.

BACKGROUND: Application of haptens to the skin induces release of immune stimulatory ATP into the extracellular space. This "danger" signal can be converted to immunosuppressive adenosine (ADO) by the action of the ectonucleotidases CD39 and CD73, expressed by skin and immune cells. Thus, the expression and regulation of CD73 by skin derived cells may have crucial influence on the outcome of contact hypersensitivity (CHS) reactions. OBJECTIVE: To investigate the role of CD73 expression during 2,4,6-trinitrochlorobenzene (TNCB) induced CHS reactions. METHODS: Wild type (wt) and CD73 deficient mice were subjected to TNCB induced CHS. In the different mouse strains the resulting ear swelling reaction was recorded along with a detailed phenotypic analysis of the skin migrating subsets of dendritic cells (DC). RESULTS: In CD73 deficient animals the motility of DC was higher as compared to wt animals and in particular after sensitization we found increased migration of Langerin+ DC from skin to draining lymph nodes (LN). In the TNCB model this led to a stronger sensitization as indicated by increased frequency of interferon-γ producing T cells in the LN and an increased ear thickness after challenge. CONCLUSION: CD73 derived ADO production slows down migration of Langerin+ DC from skin to LN. This may be a crucial mechanism to avoid over boarding immune reactions against haptens.

Close relationship between T helper (Th)17 and Th2 response in murine allergic contact dermatitis.

BACKGROUND: Repeated exposure to allergens induces chronic allergic lesions in the skin and a shift in the cutaneous cytokine milieu to T helper (Th)2. AIM: To assess the relationships between Th17 and Th2 response during allergic contact dermatitis (ACD) in mice. METHODS: ACD was induced in C57BL/6 mice by single or repeated epicutaneous challenge of 2,4,6-trinitro-1-chlorobenzene. Relationships between Th17 and Th2 response were analyzed by immunohistochemical observations and activity of cytokines on days 8 (first challenge), 18 (11th challenge), 28 (21st challenge) and 38 (31st challenge). RESULTS: On day 8, tissue levels of interleukin (IL)-17 and IL-22 were high, whereas tissue levels of IL-4 and serum IgE concentration were low. Following acute contact dermatitis, mice developed chronic eczematous lesions on day 18, and gradually improved on days 28 and 38. Tissue IL-4 and serum IgE levels corresponded to the development and improvement of chronic eczematous lesions. Numbers of Th17 cells and tissue levels of IL-17 and IL-22 rapidly decreased as IL-4 and IgE levels increased on day 18. As levels of IL-4 and IgE decreased, the number of Th17 cells and tissue levels of IL-17 and IL-22 increased again on days 28 and 38. On day 18, tissue levels of Th17 response-inducing cytokines (IL-6, IL-23 and transforming growth factor-ß) were high, and IL-23-expressing cells appeared in abundance, when Th2 response was extremely high. IL-17 injection decreased tissue IL-4 and serum IgE levels. CONCLUSIONS: Th17 correlates closely with Th2 in murine chronic ACD induced by repeated epicutaneous challenge.

Effect of the hot water extract of Artocarpus camansi leaves on 2,4,6-trinitrochlorobenzene (TNCB)-induced contact hypersensitivity in mice.

Medicinal plants with reported anti-inflammatory activity could have the potential use as anti-allergens and inhibitors of allergic contact dermatitis reactions produced by allergens and chemicals. Some species from the genus Artocarpus were reported to have anti-inflammatory activity. In the Philippines one local source is Artocarpus camansi BLANCO (Moraceae), which is utilized as an ingredient of their cuisine, and decoction of leaves is used for diabetes and baths of people with rheumatism. The objective of this study was to evaluate the effect of the hot water extract of A. camansi leaves on contact hypersensitivity (CHS) in mice. Contact hypersensitivity was induced using 2,4,6-trinitrochlorobenzene (TNCB). The results showed that the A. camansi hot water extract exhibited significant activity against the swelling produced during 24 h and 48 h post-challenge. The same responses were observed from the mice that received the kamansi ethanol-precipitate (KEP) and kamansi ethanol precipitate water-soluble (KEPWS) fractions. Since the high molecular mass fraction showed the significant activity, we therefore speculate that the compound responsible might be a polysaccharide and/or glycoprotein. In conclusion, our results suggest that the hot water extract of A. camansi leaves might be an effective natural product to treat allergic contact dermatitis. However, further investigations are required to understand the mechanisms involved.

Relating skin sensitizing potency to chemical reactivity: reactive Michael acceptors inhibit NF-κB signaling and are less sensitizing than S(N)Ar- and S(N)2- reactive chemicals.

The skin sensitization potency of chemicals is partly related to their reactivity to proteins. This can be quantified as the rate constant of the reaction with a model peptide, and a kinetic profiling approach to determine rate constants was previously proposed. A linear relationship between the skin sensitization potency in the local lymph node assay (LLNA) and the rate constant for Michael acceptors was reported, characterized by a relatively flat regression line. Thus, a 10-fold increase of reactivity correlates to an increase of the sensitization potential of only 1.7-fold. Here, we first validate this model by repeating previous data and testing additional Michael acceptors and prove that the model is both reproducible and robust to the addition of new data. Chemicals of different mechanistic applicability domains, namely, S(N)Ar- and S(N)2-reactive sensitizers, were then tested with the same kinetic profiling approach. A linear relationship between sensitization potency in the LLNA and rate constants was also found, yet with a much steeper slope, i.e., for S(N)Ar- and S(N)2-reactive sensitizers, increasing reactivity correlates to a much stronger increase in sensitization potency. On the basis of the well-known inhibitory activity of some Michael acceptors on IKK kinase, it was hypothesized that the difference in the slopes is due to the specific anti-inflammatory potential of Michael acceptor chemicals. Therefore, all chemicals were tested for anti-inflammatory activity in a reporter gene assay for the inhibition of NF-κB activation. Increasingly reactive Michael acceptors have increasing anti-inflammatory potential in this assay, whereas no such biological activity was detected for the S(N)Ar and S(N)2 reactive sensitizers. Thus, the increasing reactivity of Michael acceptors confers both anti-inflammatory and skin sensitizing/pro-inflammatory potential, which may partially neutralize each other. This may be the reason for the relatively weak relationship between the potency in the LLNA and the rate constant of this particular group of chemicals.

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.

Synergetic effects of prednisolone and olopatadine on atopic dermatitis model of hairless mice.

We investigated the synergetic effects of glucocorticoid and histamine H1 receptor antagonists on an atopic dermatitis model. Hairless mice were used in this study and an atopic dermatitis model was made by repeated application of 2,4,6-trinitrochlorobenzene. The effects of glucocorticoid, histamine H1 receptor antagonists, and the simultaneous use of these drugs were investigated by measuring scratching behavior, skin symptoms and nerve growth factor (NGF) in the skin. Topical application of prednisolone significantly inhibited scratching behavior, skin symptoms and NGF contents in the skin by repeated application. Olopatadine also showed a significant effect on scratching behavior and NGF contents in the skin, whereas chlorpheniramine showed no significant inhibitory effect on these indices. Furthermore, the combined use of prednisolone and olopatadine potentiated the inhibition of scratching behavior, skin symptoms, and NGF in the skin. From these findings, olopatadine potentiated the inhibitory effect of prednisolone on the symptoms of atopic dermatitis by inhibiting NGF.

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.

Sunitinib impairs the proliferation and function of human peripheral T cell and prevents T-cell-mediated immune response in mice.

Sunitinib (sunitinib malate; SU11248; SUTENT) is a novel multi-targeted receptor tyrosine kinase inhibitor currently approved for the treatment of metastatic renal cell carcinoma. To analyze the possible use of this compound in combination with immunotherapeutic approaches, we investigated the effects of sunitinib on the human peripheral T cells and the induction of primary immune responses in mice. Sunitinib inhibited the proliferation of primary human T cells from normal healthy volunteers as well as from renal cell carcinoma (RCC) and other cancer patients. The inhibition was recoverable after drug withdrawal because sunitinib did not induce T-cell apoptosis even at 0.8 muM. In addition, sunitinib led to accumulation in G(0)/G(1) phase of the cell cycle, inhibition of cytokine production, downregulation of activation markers expression and blockade of Zap-70 signaling in the T cells. Sunitinib significantly reduced the ear swelling induced by picryl chloride in mice. In light of these findings, the effects of sunitinib on the immune system should be emphasized for the therapy of metastatic renal cell carcinoma patients to avoid the impairment of T lymphocytes.

Analysis of the mechanism for the development of allergic skin inflammation and the application for its treatment:establishment of a modified allergic dermatitis model in mouse ear lobes by application of 12-O-tetradecanoyl phorbol 13-acetate: putative involvement of thymic stromal lymphopoietin and roles of histamine.

We established a novel allergic dermatitis model in mouse ear lobes in which antigen-nonspecific inflammation was induced by painting 12-O-tetradecanoylphorbol 13-acetate (TPA) between sensitization and challenge with picryl chloride (PiCl). This model has an advantage for analyzing atopic dermatitis-like inflammation within a short period. Analysis of the time course changes in the PiCl-induced swelling showed that the allergic inflammation was shifted from a delayed-type response to a biphasic response consisting of a weak immediate-phase response and a late-phase response by painting with TPA. The application of TPA increased the PiCl-induced infiltration of eosinophils and mast cells at the inflammatory site and shifted the cytokine milieu from Th1 to Th2. The expression of the Th2-inducing cytokine thymic stromal lymphopoietin (TSLP) mRNA was also increased by TPA. These findings suggested that the induction of antigen-nonspecific inflammation by TPA before the antigen challenge enhanced the Th2 response and modified the PiCl-induced delayed type-hypersensitivity. Using this model, we clarified that histamine plays significant roles in the early-phase swelling via H(1) receptors and the late-phase swelling via H(3)/H(4) receptors. Thus, we suggested the usefulness of the combined treatment with an H(1) antagonist and an H(4) antagonist for the suppression of atopic dermatitis.

The role of IgE and repeated challenge in the induction of persistent increases in scratching behavior in a mouse model of allergic dermatitis.

Previously, we indicated that athymic BALB/c-nu/nu (nude) mice that had been repeatedly treated with 2,4,6-trinitrochlorobenzene (TNCB) failed to exhibit chronic scratching behavior in spite of the accumulation of dermal mast cells in the lesion. The mice also failed to produce specific IgE or potent dermatitis. In the present study, therefore, we aimed to examine the role of IgE and repeated hapten treatment in the induction of scratching behavior and dermatitis using nude mice and trinitrophenol (TNP)-specific IgE-transgenic mice. The ears of nude mice were treated with TNCB 6 times at intervals of 48 h, and TNP-specific IgE was administered to the mice intravenously before the sixth TNCB treatment. The nude mice that had been supplemented with IgE exhibited a persistent increase in scratching behavior and continuous degranulation of mast cells. Furthermore, a potent immediate ear swelling was induced, although no biphasic dermatitis pattern was observed. On the other hand, the IgE-transgenic mice failed to exhibit persistent increases in scratching behavior after a single TNCB treatment, although biphasic ear swelling was observed. These results indicate that specific IgE plays an essential role in the induction of persistent increases in scratching behavior and continuous degranulation of mast cells. Furthermore, repeated challenge with the hapten also plays an important role in persistent increases in scratching behavior through accumulation and continuous activation of mast cells.

IL-20 receptor 2 signaling down-regulates antigen-specific T cell responses.

The recently described cytokines IL-19, IL-20, and IL-24 share structural homology with IL-10 and are therefore classified as members of the IL-10 family of cytokines. Although it has long been speculated that signaling by their heterodimeric receptor complexes (IL-20R1/IL-20R2 and IL-22R/IL-20R2) influences immunological processes, the target cells for this group of cytokines are still unclear. By generating a knockout mouse strain deficient for the common IL-20R beta-chain (IL-20R2), we show that IFN-gamma and IL-2 secretion is significantly elevated after stimulation of IL-20R2-/--deficient CD8 and CD4 T cells with Con A or anti-CD3/CD28 in vitro. IL-10 secretion by activated IL-20R2-/- CD4 cells was diminished. Consistent with our in vitro results, significantly more Ag-specific CD8 IFN-gamma+ and CD4 IFN-gamma+ T cells developed to locally applied DNA vaccines in IL-20R2-deficient mice. In a T cell-dependent model of contact hypersensitivity, IL-20R2 knockout mice were more sensitive to the contact allergen trinitro-chloro-benzene. Thus, IL-20R2 signaling directly regulates CD8 and CD4 T cell answers in vitro and in vivo. For the first time, we provide evidence that IL-19, IL-20, and IL-24 are part of a signaling network that normally down-modulates T cell responses in mice.

Modification of the picryl chloride-induced allergic dermatitis model in mouse ear lobes by 12-O-tetradecanoylphorbol 13-acetate, and analysis of the role of histamine in the modified model.

BACKGROUND: In atopic dermatitis, inflammation induced by antigen-nonspecific stimuli further enhances the allergic inflammation. However, there is no experimental model in which allergic dermatitis is evoked where the inflammation has been induced by antigen-nonspecific stimuli. Here, we established a novel dermatitis model in mice and analyzed the role of histamine. METHODS: After sensitization with picryl chloride (PiCl) by painting on ear lobes of cyclophosphamide-treated mice, 12-O-tetradecanoylphorbol 13-acetate (TPA) was painted twice at the same site, and then allergic inflammation was induced by painting PiCl. Histamine antagonists and cyclosporine A (CsA) were administered intravenously. RESULTS: The application of TPA shifted the PiCl-induced allergic inflammation from a delayed-type response to a biphasic response, increased the infiltration of eosinophils and mast cells at the inflammatory site, shifted the cytokine milieu from Th1 to Th2 and induced the expression of thymic stromal lymphopoietin in the ear lobes. The PiCl-induced increase in the thickness of the ear lobe in the immediate phase was suppressed by the H1 antagonist pyrilamine. In contrast, the increase in the swelling in the late phase and the infiltration of eosinophils were suppressed by the H3/H4 antagonist thioperamide. The inhibitory effect of the combined treatment with pyrilamine and thioperamide on the TPA-modified contact dermatitis was as potent as that of CsA. CONCLUSION: Induction of the antigen-nonspecific inflammation by TPA enhanced the PiCl-induced allergic inflammation. Histamine plays significant roles in the early-phase swelling via H1 receptors, and the late-phase swelling via H3/H4 receptors in this TPA-modified allergic dermatitis model.

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 casei subsp. casei together 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.

[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.