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Autoimmune adverse events are a concern in patients treated with blocking anti-CTLA-4-mAb for solid and hematological tumors. Patient and mouse data on the contribution of a quantitative or qualitative defect of regulatory T cells (T(reg)) in this autoimmune phenomenon are conflicting. We have previously shown that a treatment course with blocking anti-CTLA-4-mAb in murine allogeneic bone marrow chimeras induces an antileukemic response in close association with systemic autoimmunity. Here, we used this model to investigate the effect of CTLA-4-blocking therapy on the kinetics of T(reg) frequency and function. As previously published, CTLA-4-blocking treatment, initiated on day 20 after bone marrow transplantation, led to overt autoimmunity by day 35. CD4(+)Foxp3(+) T(reg) frequency was determined (flowcytometry) on day 21, 23, 25 and 35: treated chimeras showed an expansion of CD4(+)Foxp3(+) T(reg) frequencies on day 25 and 35, without a prior frequency decrease. The T(reg) expansion occurred selectively in the recipient-derived CD4+ T-cell compartment. In vitro, purified CD4(+)CD25(+)FR4(high) T(reg) from 'day 35' autoimmune and control chimeras showed equal suppressive effects towards self-antigen-specific autoimmune T cells. Purified CD4(+)CD25(high)FR4(high) T(reg) from 'day 35' treated chimeras showed increased IL-10 and IFN-gamma mRNA-expression (RT-PCR) relative to control chimeras. In this model of CTLA-4-blockade-induced autoimmunity after allogeneic bone marrow transplantation, anti-CTLA-4-mAb gives rise to a progressive expansion - without a prior transient reduction - of T(reg) cells. T(reg) of autoimmune animals do not show a defect in in vitro suppressive function but show an in vivo activated cytokine profile, suggesting that the expansion occurs as a compensatory phenomenon to control autoimmunity.

Haptoglobin (HP) is an acute phase protein synthesized by liver cells in response to IL-6. HP has been demonstrated to modulate the immune response and to have anti-inflammatory activities. To analyze HP's effect on autoimmune inflammation, we here studied the course of EAE induced by immunization of Hp knockout (Hp(-/-)) and syngeneic WT mice with myelin oligodendrocyte glycoprotein peptide (MOG(35-55)). Hp(-/-)mice suffered from a more severe disease that was associated with increased expression of IL-17A, IL-6, and IFN-gamma mRNA in the CNS and with a denser cellular infiltrate in the spinal cord. During the recovery phase, a significantly higher number of myeloid DC, CD8+ cells, IL-17+ CD4+ and IFN-gamma+ CD4+ cells persisted in the CNS of Hp(-/-) mice. Absence of HP affected the priming and differentiation of T cells after MOG(35-55) immunization, as levels of Th2 cytokines produced in response to MOG stimulation by Hp(-/-) T cells were reduced. These results suggest that HP plays a modulatory and protective role on autoimmune inflammation of the CNS.

Blocking of costimulatory signals for T cell activation leads to tolerance in several transplantation models, but the underlying mechanisms are incompletely understood. We analyzed the involvement of regulatory T cells (Treg) and deletion of alloreactive cells in the induction and maintenance of tolerance after costimulation blockade in a mouse model of graft-vs-host reaction. Injection of splenocytes from the C57BL/6 parent strain into a sublethally irradiated F(1) offspring (C57BL/6 x C3H) induced a GVHR characterized by severe pancytopenia. Treatment with anti-CD40L mAb and CTLA4-Ig every 3 days during 3 wk after splenocyte injection prevented disease development and induced a long-lasting state of stable mixed chimerism (>120 days). In parallel, host-specific tolerance was achieved as demonstrated by lack of host-directed alloreactivity of donor-type T cells in vitro and in vivo. Chimerism and tolerance were also obtained after CD25(+) cell-depleted splenocyte transfer, showing that CD25(+) natural Treg are not essential for tolerance induction. We further show that costimulation blockade results in enhanced Treg cell activity at early time points (days 6-30) after splenocyte transfer. This was demonstrated by the presence of a high percentage of Foxp3(+) cells among donor CD4(+) cells in the spleen of treated animals, and our finding that isolated donor-type T cells at an early time point (day 30) after splenocyte transfer displayed suppressive capacity in vitro. At later time points (>30 days after splenocyte transfer), clonal deletion of host-reactive T cells was found to be a major mechanism responsible for tolerance. ispartof: Journal of Immunology vol:181 issue:2 pages:1034-1042 ispartof: location:United States status: published

Background Recombinant hypoallergens that display reduced allergenicity but retain T-cell reactivity represent promising candidates to improve the safety and efficacy of allergen-specific vaccines or immunotherapy. Objective The current study reports the immunologic characterization of a hypoallergenic variant of the major mite allergen Der p 1. Methods The recombinant proform of Der p 1 (ProDer p 1) was expressed in Escherichia coli (ProDer p 1 coli ), purified and characterized at the level of its secondary structure, and IgE and T-cell reactivities. Moreover, the prophylactic potential of ProDer p 1 coli vaccinations was evaluated in a murine Der p 1 sensitization model. Results After purification and refolding, ProDer p 1 coli remained aggregated with a higher β-sheet content and altered Der p 1 conformational epitopes compared with the correctly folded monomeric ProDer p 1 produced in Chinese hamster ovary cells. Both ProDer p 1 forms were able to retain the Der p 1–specific T-cell reactivity but direct ELISA, competitive inhibition, and rat basophil leukemia assays clearly showed that ProDer p 1 coli displays a very weak IgE reactivity. Mice vaccinations with aggregated ProDer p 1 adjuvanted with alum induced a T H 1-biased immune response that prevented the subsequent allergic response after Der p 1 sensitization and airway challenge with aerosolized mite extracts. Furthermore, ProDer p 1 coli treatment inhibited the development of airway eosinophilia and airway hyperresponsiveness to inhaled methacholine. Conclusion Aggregated forms of Der p 1 could represent hypoallergens suitable for the prevention of mite allergy.

Allergen inhalation by sensitized asthmatics induces an IgE and mast cell dependent bronchoconstriction and a Th2-dependent inflammatory airway reaction, mucus hypersecretion and airway hyperreactivity. The link between T cells and bronchoconstriction remains controversial. Here we analyzed allergen-induced changes in airway tone in ovalbumin-sensitized mice with established allergic airway inflammation. Inhalation of nebulized ovalbumin elicited a dose-dependent and allergen-specific increase in airway resistance and bronchial tone with a concomitant increase of lymphocytes and eosinophils in bronchoalveolar lavage fluid. A Th2 pattern of cytokine expression and increased mRNA expression of MCP-1, RANTES and VCAM-1 were demonstrated. Anti-CD4 monoclonal antibody treatment prior to provocation decreased IL-13 and VCAM-1 mRNA expression and abolished the increase in bronchial tone and the inflammatory response. We conclude that allergen inhalation in sensitized mice induces airway narrowing similar to the late asthmatic reactions in humans and that this phenomenon is based on activation of CD4+ T cells.

Recent insights regarding the development of allergic diseases such as allergic rhinitis, asthma and atopic eczema are based on the functional diversity of T helper (Th)1 and Th2 lymphocytes. Th2 cells (secreting Interleukin (IL)-4, IL-5, IL-9 and IL-13) are considered to be responsible for the induction and for many of the manifestations of atopic diseases. Local overproduction of Th2 cytokines at the site of allergic inflammation, and an intrinsic defect in the production of IFN-gamma by Th1 cells in atopic individuals, have now been reported by several authors. Both IFN-gamma and IL-10 have been suggested to play a modulatory role in the induction and maintenance of allergen-specific tolerance in healthy individuals. However, recent studies indicate that Th1 cells, secreting IFN-gamma might cause severe airway inflammation. On the other hand, 'inflammatory T cells' or Th17 cells, producing IL-17, could represent a link between T cell inflammation and granulocytic influx as observed in allergic airway inflammation. We focus in this review on local (at the side of inflammation) T cell cytokine production and cytokine production by circulating T cells (after in vitro restimulation) from individuals with allergic airway disease, rhinitis and/or asthma. We furthermore review the changes in local T cell cytokine production and/or cytokine production by circulating T cells (after restimulation in vitro) from allergic/asthmatic individuals after treatment with anti-inflammatory agents or immunotherapy. Finally, we discuss whether measuring these T cell cytokines in the airways might be of diagnostic importance or could help to follow-up patients with allergy/asthma.

Xenoantibody production directed at a wide variety of T lymphocyte-dependent and T lymphocyte-independent xenoantigens remains the major immunologic obstacle for successful xenotransplantation. The B lymphocyte subpopulations and their helper factors, involved in T-cell-independent xenoantibody production are only partially understood, and their identification will contribute to the clinical applicability of xenotransplantation. Here we show, using models involving T-cell-deficient athymic recipient mice, that rapidly induced, T-cell-independent xenoantibody production is mediated by marginal zone B lymphocytes and requires help from natural killer (NK) cells. This collaboration neither required NK-cell-mediated IFN-gamma production, nor NK-cell-mediated cytolytic killing of xenogeneic target cells. The T-cell-independent IgM xenoantibody response could be partially suppressed by CD40L blockade. ispartof: BLOOD vol:110 issue:12 pages:3926-3935 ispartof: location:United States status: published

Background: Tumor necrosis factor (TNF) plays an important role in the pathogenesis of several inflammatory diseases. Its expression is increased in inflamed mucosa of Crohn's disease patients and anti-TNF treatment improves mucosal inflammation. Besides neutralization, induction of apoptosis of monocytes/macrophages and T cells is thought to be an important mechanism of action of the anti-TNF monoclonal antibody therapy. The aim was to investigate the pathogenic role of TNF in hapten-induced colitis models and to study the relationship between apoptosis induction and disease remission. Methods: In 2 murine colitis models (trinitrobenzene sulphonic acid, TNBS, and oxazolone colitis), mice were injected daily with anti-TNF monoclonal antibody (mAb). Macrophages were collected from lamina propria of TNBS colitis mice. 7AAD and anti-active-caspase-3 staining were used to study DNA degradation and intracellular caspase activation. A pan-caspase inhibitor, N-benzyloxycarbonyl-Val-Ala-Asp-fluoromethyketone (Z-VAD-FMK), was given to a subgroup of the colitis mice. Results: Treatment with anti-TNF effectively reduced intestinal mucosal inflammation in TNBS colitis but not in oxazolone colitis. Effectiveness was evidenced by a more rapid recovery of body weight and reduced cell infiltration, and downregulation of proinflammatory cytokines interferon-gamma (IFN-γ), TNF, and IL-18 at the mRNA level. Apoptosis was induced in lamina propria macrophages after treatment with anti-TNF, and it was abrogated through short-term pretreatment with Z-VAD-FMK. Conclusion: Anti-TNF downregulates proinflammatory cytokines and decreases cell infiltration in the bowel after TNBS application. The remission-inducing effect of anti-TNF may partly rely on apoptosis induction. (Inflamm Bowel Dis 2006)

Acute rejection (AR) is an important complication that can occur after lung transplantation and constitutes a risk factor for bronchiolitis obliterans syndrome, which is characterised by a neutrophilic airway inflammation. The specific aim of this study was to investigate the role of interleukin (IL)-17, which promotes chemotaxis of neutrophils by inducing IL-8 production, in AR. Cell differentials, mRNA and protein levels were quantified in bronchoalveolar lavages (BALs) taken from patients at 28 and 90 days after lung transplantation. The patient's rejection status was assessed by transbronchial biopsy. An AR was found in nine out of the 26 patients examined, 28 days after transplantation. The number of BAL neutrophils and lymphocytes were increased in these patients. IL-17 mRNA and protein levels in the BAL were increased in patients with AR. Analysis of BAL obtained at day 90 after transplantation, demonstrated that the increase in IL-17 had disappeared, whereas the increase in neutrophils and lymphocytes persisted. These data showed that interleukin-17 is temporarily upregulated in bronchoalveolar lavage during acute rejection. The number of lymphocytes and neutrophils are increased in bronchoalveolar lavage during acute rejection and may persist up to 2 months after acute rejection. These findings suggest that interleukin-17 is important in the pathophysiology of acute lung rejection. ispartof: European Respiratory Journal vol:27 issue:4 pages:779-87 ispartof: location:England status: published

BACKGROUND: T-helper type 2 (Th2) cells play an important role in the pathogenesis of allergic diseases. Recent studies have demonstrated that allergen-specific T cells can also be found in the blood of healthy individuals. Both IL-10 and IFN-gamma might modulate the induction and maintenance of allergen-specific tolerance. AIM: To study the phenotype and functional characteristics of allergen-specific T cells in healthy non-atopic children. METHODS: Peripheral blood mononuclear cells (PBMC) from 13 symptomatic house dust mite (HDM)-allergic children and from nine matched healthy control children were stimulated with recombinant (r)Der p 2, a major allergen from HDMs. RESULTS: Stimulation with rDer p 2 resulted in Th2 cytokine production in cultures of PBMC from allergic but not from healthy children. In contrast, IL-10 and IFN-gamma were induced in PBMC cultures from both healthy and HDM-allergic children. Intracellular staining revealed that IL-10 and IFN-gamma are largely produced by the same T cells. Stimulation of T cells from healthy children with rDer p 2 also induced expression of inducible costimulator (ICOS) on a small T cell subset. CONCLUSION: Allergen-specific memory T cells from healthy non-atopic children produce IL-10 and IFN-gamma (but not Th2 cytokines) and express ICOS upon stimulation. These cells might be responsible for a normal immune balance after allergen encounter in non-atopics.

Background The role of Th2 cells (producing interleukin (IL-)4, IL-5 and IL-13) in allergic asthma is well-defined. A distinct proinflammatory T cell lineage has recently been identified, called Th17 cells, producing IL-17A, a cytokine that induces CXCL8 (IL-8) and recruits neutrophils. Neutrophilic infiltration in the airways is prominent in severe asthma exacerbations and may contribute to airway gland hypersecretion, bronchial hyper-reactivity and airway wall remodelling in asthma. Aim to study the production of IL-17 in asthmatic airways at the mRNA level, and to correlate this with IL-8 mRNA, neutrophilic inflammation and asthma severity. Methods We obtained airway cells by sputum induction from healthy individuals (n = 15) and from asthmatic patients (n = 39). Neutrophils were counted on cytospins and IL-17A and IL-8 mRNA expression was quantified by real-time RT-PCR (n = 11 controls and 33 asthmatics). Results Sputum IL-17A and IL-8 mRNA levels are significantly elevated in asthma patients compared to healthy controls. IL-17 mRNA levels are significantly correlated with CD3γ mRNA levels in asthmatic patients and mRNA levels of IL-17A and IL-8 correlated with each other and with sputum neutrophil counts. High sputum IL-8 and IL-17A mRNA levels were also found in moderate-to-severe (persistent) asthmatics on inhaled steroid treatment. Conclusion The data suggest that Th17 cell infiltration in asthmatic airways links T cell activity with neutrophilic inflammation in asthma.

CD25+CD4+ regulatory T cells (Tregs) contribute to the maintenance of peripheral tolerance against self and non-self. The modulatory effects of cytokines, such as interleukin 4 (IL-4) on the function of Tregs have not been explored in detail. We here report that IL-4 prevents spontaneous apoptosis and the decline of foxp3 mRNA which were found to occur during culture of isolated Tregs. Tregs exposed to IL-4 were more potent in suppressing the proliferation of naive CD4+ T cells and they better inhibited IFN-gamma production by CD4+ T cells as compared to Tregs cultured in medium. IL-4 also enhanced membrane IL-2Ralpha (CD25) expression on Tregs above the levels observed on freshly isolated cells. IL-4-mediated effects on Treg function persisted in Tregs from Stat6-/- mice, pointing to a Stat6-independent intracellular transduction pathway. In conclusion, our data suggest that the anti-inflammatory function of IL-4 could partly be mediated by effects on Tregs function.

Although immunoregulation by several types of regulatory T cells is now clearly established in mice, the demonstration of such regulatory T cells in humans has been proven more difficult. In this study we demonstrate the induction of anergic regulatory T cells during an MLR performed in the presence of blocking mAb to the costimulatory molecules CD40, CD80, and CD86. Despite this costimulation blockade, which totally blocks T cell proliferation and cytokine production, a nonproliferating T cell subpopulation was activated to express inducible costimulator (ICOS). These ICOS+ cells were anergic when restimulated with unmanipulated allogeneic stimulator cells at the level of proliferation and Th1 and Th2 cytokine production, but they did produce IL-10. These ICOS-expressing cells also blocked the capacity of reciprocal ICOS-negative cells to proliferate and to produce cytokines. ICOS+ anergic cells could suppress allogenic responses of either primed or naive T cells through inhibition of IL-2 gene transcription. Suppression was not mediated by IL-10 and did not require ICOS-ICOS ligand interaction, but depended on cell-cell contact. Thus, a subtype of regulatory T cells in human blood can be activated in the absence of costimulatory signals from CD40, CD80, and CD86, and they can be identified by expression of ICOS after activation.

4-1BB ligand (L) expressed on antigen presenting cells (APC) interacts with 4-1BB, expressed on activated T cells and this interaction costimulates T cells to secrete cytokines and to proliferate. We investigated whether 4-1BB/4-1BBL interactions might be involved in the pathogenesis of Crohn's disease (CD). In immunohistochemistry, we found 4-1BB expression on lamina propria (LP) cells in inflamed and to a lesser extend in non-inflamed gut tissue from CD patients. mRNA levels for 4-1BB were also elevated in intestinal CD tissue. In contrast, only few 4-1BB-expressing cells were found in inflamed tissue from ulcerative colitis (UC) patients and almost no positive cells were found in control intestinal tissue. 4-1BB expression was better sustained on in vitro activated lamina propria T cells from CD patients compared to controls. Finally, agonistic anti-4-1BB antibody enhanced interferon-gamma (IFN-γ) production and proliferation of lamina propria T cells from CD patients. Taken together, our data suggest that 4-1BB/4-1BBL interactions contribute to the persistence of gut inflammation in CD.

Exercise induced bronchoconstriction (EIB) is more prevalent in elite athletes compared to controls. It is however unclear how many young athletes suffer from EIB.

CD58 is the ligand for the CD2 molecule on human T cells and has been shown to provide a co-stimulatory signal for T cell activation. However, its physiological role is still unclear. We studied the effects of co-stimulation by CD58 on the production of T(h)1-type (IL-2- and IFN-gamma) or T(h)2 type (IL-4, IL-5 and IL-10) cytokines in an in vitro culture system of purified human T cells with CD58-transfected P815 cells and with anti-CD3 as the primary stimulus. Co-stimulation of T cells by CD58 potently induced IL-10 and IFN-gamma production (at the protein and at the mRNA level), and transforming growth factor-ss production (at the mRNA level), comparable to what can be found in CD80 co-stimulated T cell cultures. In contrast, we found low to absent IL-2, IL-4, IL-5, IL-13 and tumor necrosis factor-alpha production after CD58 co-stimulation, and this was not due to suppressive effects of endogenously produced IL-10. CD80 co-stimulation strongly induced all these cytokines. Intracellular staining for cytokine expression revealed the existence of a T cell subpopulation induced by CD58 co-stimulation to produce both IFN-gamma and IL-10. We furthermore found that the selective cytokine profile induced by CD58 co-stimulation is further accentuated by rIL-12 and by rIFN-alpha. Using cyclosporin A as an inhibitor of the calcineurin enzyme, we could show that production of all cytokines in this system is calcium dependent. CD58 co-stimulation thus induces a cytokine pattern corresponding to that described for T regulatory (T(r)) 1 cells and to the pattern reported to be induced by the newly identified B7 family member, B7-H1.

SUMMARYIL-4 is a pleiotropic cytokine which is involved in the development of atopic diseases. Only limited data exist on IL-4 production in humans, and the relative contribution to atopy of either unbalanced IL-4 production, or increased IL-4-responsiveness of target cells, is still unknown. The use of a MoAb to the IL-4 receptor α-chain (IL-4Rα) enabled us to demonstrate that IL-4 production in vitro is usually underestimated, due to in vitro consumption, even in cultures of purified T cells. When IL-4 consumption was blocked, it became evident that CD80 and CD86 both provide effective costimulatory signals for high IL-4 production. Moreover, we found that even stimulation with a soluble antigen (tetanus toxoid) induces IL-4 production by T cells from healthy non-atopic donors. Both sets of data imply that IL-4 is not required for IL-4 production by memory and/or effector T cells. Our data further show that endogenous IL-4 activity modulates IL-10 and interferon-gamma production by T cells in opposite directions. The use of this receptor-blocking antibody will thus be helpful for in vitro studies on IL-4 regulation. Consumption of IL-4 by different cell types during in vitro cultures might have interfered with previous attempts to quantify IL-4 production by human T cells.

In this study, we investigated the efficiency of costimulatory signaling provided by anti-CD2 monoclonal antibodies (mAbs) for the production of type 1 (IL-2 and IFN-gamma) and type 2 (IL-4, IL-5, and IL-10) cytokines by human T cells. We cultured purified human T cells (freshly isolated from blood) with immobilized anti-CD3 mAb, either alone or in combination with anti-CD28 or anti-CD2 mAbs. When compared with the standard costimulatory signal anti-CD28, anti-CD2 mAbs (9-1 plus 9.6) were shown to be more potent costimulators of IL-4 production and to have similar activity for IL-5 production, but to be less potent for costimulation of IL-2, IL-10, and IFN-gamma production, IL-4 production was completely inhibited by cyclosporin A or by blocking IL-2 activity and its receptor. IL-4 and IL-5 were produced by CD45RO(+) T cells but not by CD45RA(+) T cells, indicating that anti-CD2 in this system costimulated type 2 cytokine production by differentiated memory cells. In the presence of IL-12, the cytokine profile was shifted to high IFN-gamma and IL-10 production and IL-4 and IL-5 production were slightly inhibited. Our data thus suggest that CD2 ligation plays an important role in the upregulation of Th2-like T cell activity (especially IL-4 production), but they also show that this effect is strongly modulated by IL-12, resulting in predominant IL-10 and IFN-gamma production instead. (C) 1997 Academic Press.

P030 High fat diet aggravates Crohn’s disease-like ileitis independently of obesity via alterations of epithelial barrier homeostasis L. Gruber1 *, S. May1, J. Fiamoncini2, V. Muller2, M. Lichtenegger3, M. Rychlik3, H. Daniel2, D. Haller1. 1Technical University Munich, Biofunctionality, ZIEL Research Center for Nutrition and Food Sciences, CDD Research Center for Diet and Disease, Freising, Germany, 2Technical University Munich, Department of Biochemistry, ZIEL Research Center for Nutrition and Food Sciences, Freising, Germany, 3Technical University Munich, Bioanalytics, ZIEL Research Center for Nutrition and Food Sciences, Freising, Germany

Mice with a deficiency in IFN-γ or IFN-γ receptor (IFN-γR) are more susceptible to collagen-induced arthritis (CIA), an experimental autoimmune disease that relies on the use of complete Freund's adjuvant (CFA). Here we report that the heightened susceptibility of IFN-γR knock-out (KO) mice is associated with a functional impairment of CD4+CD25+ Treg cells. Treatment of wild-type mice with depleting anti-CD25 antibody after CFA-assisted immunisation with collagen type II (CII) significantly accelerated the onset of arthritis and increased the severity of CIA. This is an indication of a role of Treg cells in the effector phase of CIA. IFN-γR deficiency did not affect the number of CD4+CD25+ T cells in the central and peripheral lymphoid tissues. In addition, CD4+CD25+ T cells isolated from naive IFN-γR KO mice had a normal potential to suppress T cell proliferation in vitro. However, after immunisation with CII in CFA, the suppressive activity of CD4+CD25+ T cells became significantly more impaired in IFN-γR-deficient mice. Moreover, expression of the mRNA for Foxp3, a highly specific marker for Treg cells, was lower. We further demonstrated that the effect of endogenous IFN-γ, which accounts for more suppressive activity in wild-type mice, concerns both Treg cells and accessory cells. Our results demonstrate that the decrease in Treg cell activity in CIA is counter-regulated by endogenous IFN-γ.

Rationale We aimed to investigate the role of CD4+ cells in the bronchial late phase response (LPR) in a mouse-model of asthma, characterized by an allergen-specific LPR. Methods Male Balb/C mice (6–8 weeks) were sensitized by ovalbumin (OVA) (i.p.) on alternate days from d1 till d13. The challenge phase comprised daily nebulizations of OVA from d33 till d40. On d47 500ul PBS (control) or 100 μg GK1.5 (depleting anti-CD4 monoclonal antibody) was administered i.p. The LPR was induced by nebulized OVA on d50. The enhanced pause (PenH) was measured every 30 seconds during 6 hours by body plethysmography. The mice were sacrificed for flowcytometric analysis of whole blood, differential cell counts and cytokine measurements on broncho-alveolar lavage (BAL), and for RT-PCR on lung tissue. Results Within the CD3+ population, GK1.5 diminished the CD4+ cells by more than 90%. In the control mice an LPR could be induced with PenH peaking at 240 min whereas in the GK1.5 group the LPR was inhibited. The area under the curve of the PenH/time curve was lower in the GK1.5 mice compared to the control mice (p=0.03, t-test). BAL lymphocyte, monocyte and eosinophil counts were lower in the GK1.5 group (p=0.03, p=0.03 and p=0.02 respectively, t-test). BAL IFN-γ was lower in the GK1.5 group (p=0.02, t-test). IL-4, IL-5 and IFN-γ-mRNA tended to be decreased in the GK1.5 group. Conclusions Blocking/depleting of CD4+ cells inhibits the LPR in a mouse model of asthma. Thus, CD4+ lymphocytes might play a key role in the induction of the bronchial LPR.

Since glycolipid biosynthesis is potentially involved in immunological and inflammatory responses, we tested the effect of a novel inhibitor of intracellular glycolipid biosynthesis N-(5-adamantane-1-yl-methoxy-pentyl)-deoxynojirimycin (AMP-DNM) in two hapten-induced colitis models: trinitrobenzene sulphonic acid (TNBS)- and oxazolone (4-ethoxymethylene-2phenyl-2oxazoline-5-one; Oxa)-induced colitis. AMP-DNM was given either by intraperitoneal injection or orally via the diet. Mice treated with AMP-DNM had less severe colitis and a more rapid weight recovery, less edema and less wall thickness. Cellular infiltration, goblet cell loss and myeloperoxidase (MPO) activity were reduced in colons of AMP-DNM-treated animals. Intralesional IFN-gamma and IL-18 production were lower in mice of the AMP-DNM-treated groups. Furthermore, AMP-DNM treatment reduced the serum anti-TNBS and anti-Oxa antibody levels. Our findings show that the glycolipid biosynthesis inhibitor AMP-DNM has a strong anti-inflammatory and immune suppressive activity on both TNBS- and Oxa-induced colitis. The data also provide evidence that glycolipid biosynthesis is involved in the inflammatory cascade in these inflammatory bowel disease (IBD) models.

SUMMARYIL-4 plays a key role in driving the differentiation of CD4+ Th precursors into Th2 cells, both in mice and in humans. The source of IL-4 during primary immune responses is, however, still debated. When IL-4 consumption in in vitro T cell cultures was blocked with a MoAb to the IL-4 receptor α-chain (IL-4Rα), it became evident that freshly isolated naive (CD45RO−) CD4+ T cells from adults or cord blood produce IL-4 upon activation with anti-CD3 and CD80. IL-4 production by naive T cells is strictly IL-2-dependent. Endogenous IL-4 activity in naive CD4+ T cell cultures modulates the production of interferon-gamma (IFN-γ) on the one hand and IL-5 and IL-13 on the other hand in opposite directions, and it is partly responsible for the low IFN-γ production by cord blood T cells. Comparison of the ratio of IL-4/IFN-γ in supernatants of T cell cultures reveals a skewing towards IL-4 production by cord blood T cells, while naive T cells from (non-atopic) adults predominantly produce IFN-γ. We conclude that CD4+ naive T cells can produce IL-4 without the need for Th2 differentiation, and therefore that they can be the initial source of IL-4 required at the time of priming for T cell differentiation into Th2 cells.