Peripheral blood CD4+ and CD8+ T cell type 1 and type 2 cytokine production in atopic asthmatic and normal subjects

BACKGROUND: Increased production of IL-4 and IL-5 and decreased production of IFN-gamma by CD4+ T cells has been implicated in asthma pathogenesis. However, CD8+ T cells also produce type 1 and type 2 cytokines and the relative roles of CD4+ and CD8+ T cell cytokine production in asthma have not been previously studied. OBJECTIVE: To determine the production of the type 1 and type 2 cytokines by CD4+ and CD8+ T cell subsets in asthmatic and normal subjects. METHODS: Intracellular cytokine staining for IL-4, -5, -10, -13 and IFN-gamma was analysed in peripheral blood CD4+ and CD8+ T cells from 24 atopic asthmatic and 20 normal subjects. RESULTS: Both subsets of T cells produced all cytokines studied and there were no significant differences between CD4+ and CD8+ T cells in their capacity to produce either type 1 or type 2 cytokines. There were significantly increased frequencies of IFN-gamma-positive CD4+ (13.1 +/- 2.4%, vs. 7.3 +/- 1.4%) and CD8+ (20.0 +/- 2.9%, vs. 9.6 +/- 2.1%) T cells in asthmatic subjects compared with normal subjects (P < 0.05), but not in frequencies of CD4+ or CD8+ T cells staining positively for IL-4, -5, -10 or -13. CONCLUSION: The frequencies of peripheral blood CD8+ T cells producing type 1 and type 2 cytokines are comparable with the frequencies of CD4+ T cells. There was an increased frequency of IFN-gamma producing CD4+ and CD8+ T cells in asthmatic compared with normal subjects. Further studies investigating T cells derived from the airways and investigating various stages within the disease process are required to further elucidate the importance of type 2 and type 1 T cell cytokine production in the pathogenesis of human allergic disease.     

Thymic differentiation of TCRαβ+ CD8αα+ IELs

Summary:  Intraepithelial lymphocytes (IELs) contain several subsets, but the origin of the T-cell receptor (TCR)αβ⁺ CD8αα⁺ IELs has been particularly controversial. Here we provide a synthesis, based on recent work, that attempts to unify the divergent views. The intestine has a primordial function in lymphopoiesis, and precursors with the potential to differentiate into T cells are found both in the epithelium and underlying lamina propria. Moreover, the thymus has been reported to export cells to the intestine that are not fully differentiated. TCRαβ⁺ CD8αα⁺ IELs can differentiate in the intestine from each of these sources, but in normal euthymic mice, the thymus appears to be the major source for TCRαβ⁺ CD8αα⁺ IELs. This unique IEL subset is a self-reactive population that requires exposure to self-agonists for selection in the thymus, similar to other regulatory T-cell populations. IELs transition through a double-positive (DP) intermediate in the thymus, but they originate from a subset of the DP cells that can be identified by its expression of CD8αα homodimers. The agonist-selected cells in the thymus are TCRβ⁺ but CD4 and CD8 double negative. The evidence suggests that reacquired expression of CD8αα and downregulation of CD5 occur after thymus export, perhaps in the intestine under the influence of interleukin-15. As a result of agonist exposure, a new gene expression program is activated. Therefore, the increased understanding of the developmental origin of TCRαβ⁺ CD8αα⁺ IELs may help us to understand how they participate in immune regulation and protection in the intestine.     

Wasp venom immunotherapy induces a shift from IL-4-producing towards interferon-gamma-producing CD4+ and CD8+ T lymphocytes

BACKGROUND: Venom immunotherapy (VIT) has proven to be very effective in hymenoptera venom anaphylaxis. However, the underlying immunoregulatory mechanisms of venom immunotherapy remain poorly understood. Recent studies measured the total amount of cytokine in culture supernatans, suggesting a shift in cytokine production from Th2 to a Th1 cytokine profile during VIT. We wanted to examine the contribution of specific T lymphocyte subpopulations, which is impossible using an extracellular method to determine cytokines in supernatants. OBJECTIVE: The present study was designed to evaluate the effect of VIT on the percentages of type 1 (IL-2, interferon-gamma (IFN-gamma)) and type 2 (IL-4) CD4+ and CD8+ T lymphocytes of patients with wasp venom anaphylaxis during immunotherapy. METHODS: Peripheral blood mononuclear cells of 20 individuals with a history of wasp sting anaphylaxis and a positive serum wasp venom specific IgE were isolated and in vitro stimulated with phorbol-12-myristate-13-acetate and ionomycin before VIT, at the end of a 5-day semirush VIT and at 6 months during VIT. Three-colour flow cytometric analysis was used for intracellular cytokine (IL-2, IFN-gamma, IL-4) detection in CD4+ (CD3+CD8-) T lymphocytes and CD8+ (CD3+CD8+) T lymphocytes. RESULTS: At the end of a 5-day semirush VIT, there was a significant decrease in percentage of IL-4-producing CD4+ and CD8+ T cells, compared with cytokine-producing cells before VIT (P = 0.0002 and 0.004). After 6 months of VIT, patients showed an increased number of IL-2-producing stimulated CD4+ and CD8+ lymphocytes compared with values before VIT (P = 0.002 and P = 0.0003). A higher amount of IFN-gamma-producing stimulated CD4+ and CD8+ cells was found after 6 months of VIT (P = 0.001 and P = 0.0006). There was no correlation between cytokine-producing cells and specific IgE for wasp. CONCLUSION: Venom immunotherapy induced a shift from IL-4-producing towards IFN-gamma-producing CD4+ as well as CD8+ T lymphocytes.     

Fel d 1-derived T cell peptide therapy induces recruitment of CD4+CD25+; CD4+ interferon-γ+ T helper type 1 cells to sites of allergen-induced late-phase skin reactions in cat-allergic subjects

BACKGROUND: Specific immunotherapy with whole allergen extracts is associated with local accumulation of IFN-gamma+ and CD25+ cells indicating recruitment of activated T-helper type 1 (Th1) and/or T regulatory cells. We have studied allergen-induced, late-phase skin biopsies before and after T cell peptide therapy for evidence of alterations in the pattern of local recruitment of Th1, T-helper type 2 (Th2) and T regulatory cells. OBJECTIVE: To evaluate the effect of T cell peptide therapy on the allergen-induced cutaneous late-phase reaction. METHODS: Increasing doses of synthetic Fel d 1-derived peptides were administered (by intradermal injection) to eight cat-allergic asthmatics at 14-day intervals. Twenty-four-hour skin biopsies were taken from whole cat allergen- and diluent-injected sites, before and after treatment and studied by immunohistochemistry and in situ hybridization. RESULTS: Fel-d 1 peptides decreased airway hyper-responsiveness (P = 0.02) and inhibited the late-phase cutaneous reaction (LPCR) to whole cat allergen (P = 0.03). This was associated with significant increases (post- vs. pre-treatment) in the number of cutaneous CD4+/IFN-gamma+ (P = 0.03) and CD4+/CD25+ cells (P = 0.04), but not in CD4+/IL-10+ or CD4+/CTLA-4+ cells. CONCLUSIONS: Treatment with allergen-derived T cell peptides results in allergen-dependent recruitment to the skin of Th1, rather than T regulatory cells, to cutaneous late-phase reaction sites.     

Differential effect of CD8(+) and CD8(-) dendritic cells in the stimulation of secondary CD4(+) T cells

Dendritic cells (DC), in their role in initiation of the adaptive immune response, have been extensively studied for their capacity to interact and stimulate naive T cells. Subsets of mature murine DC isolated directly from the spleen have been shown to differ in their ability to induce proliferative responses in both primary CD4(+) and primary CD8(+) T cells; the myeloid-related CD8alpha(-) DC induce a more intense or prolonged proliferation of naive T cells than do the lymphoid-related DC bearing CD8alpha despite similar expression of MHC and co-stimulatory molecules. Here we examine the interaction of these DC subpopulations with T cells already in the activated or memory state which are known to have greater sensitivity to antigen stimulation and bear receptors with increased capacity for signal transduction. We show that influenza virus-specific CD4(+) T cell clones and splenic T cells from peptide-primed animals proliferated in response to antigen presented by separated splenic CD8(-) DC. In contrast, these T cells showed only weak, if any, proliferation in response to CD8(+) DC despite observable cluster formation in the cultures. The differential between the two DC types in inducing proliferation was even more pronounced than previously seen with primary T cells and did not reflect differential longevity of the DC in culture, altered response kinetics or deviation from IL-2 to IL-4 induction with CD8(+) DC, but was related to the levels of IL-2 induced. The deficiency in the CD8(+) DC was not overcome by using infectious virus rather than synthetic peptide as the antigen source. These results show that lymphoid-related CD8(+) splenic DC, despite their mature phenotype, fail to provide appropriate signals to secondary CD4(+) T cells to sustain their proliferation.     

CD4+ T cells from mice with intestinal immediate-type hypersensitivity induce airway hyperreactivity

BACKGROUND: A subset of food-allergic patients does not only respond clinically with symptoms in the gastro-intestinal tract but also with asthmatic reactions. OBJECTIVE: The aim of this study was to analyse whether CD4+ T cells from mice with intestinal immediate-hypersensitivity reactions to food allergen are involved in the development of experimental asthma. METHODS: BALB/c mice were intraperitoneally sensitized to ovalbumin (OVA), followed by repeated intra-gastric (i.g.) OVA challenges. Control animals were either sham-sensitized or sham-challenged with phosphate-buffered saline (PBS). Duodenum, jejunum, ileum and colon were histologically examined. CD4+ T cells from mesenteric lymph nodes were transferred from various donor groups into recipient mice that received either OVA or PBS aerosol challenges. Recipients were analysed by measurements of lung function using head-out body-plethysmography and examination of broncho-alveolar lavage and lung histology. RESULTS: The highest levels of OVA-specific IgE antibody levels were detected in OVA-sensitized and OVA-challenged mice. Throughout the lower intestinal tract, a marked infiltration with eosinophils was observed, and goblet cell numbers as well as goblet cell area were significantly increased. The villus/crypt ratio was decreased compared with controls. The transfer of CD4+ T cells from mesenteric lymph nodes of OVA-sensitized and OVA-challenged mice triggered airway hyperreactivity and eosinophilic airway inflammation in recipients aerosol challenged with OVA, but not with PBS. CONCLUSION: We conclude that CD4+ T cells from mesenteric lymph nodes of mice with allergen-induced immediate-type hypersensitivity reactions in the gut are able to transfer the phenotype of experimental asthma.     

Allergen-induced cytokine phenotypes in mice: role of CD4+ and CD8+ T cell populations

BACKGROUND: CD4+ T cells expressing type 2 cytokines have been implicated in the pathogenesis of asthma to high-molecular-weight allergens. Topical exposure of BALB/c strain mice to low-molecular-weight chemical contact and respiratory allergens stimulates type 1 and type 2 cytokine secretion phenotypes, respectively. OBJECTIVE: To examine the relative frequencies of cytokine-positive CD4+ and CD8+ T cells and their contributions to these cytokine secretion profiles. Methods Draining auricular lymph nodes were isolated 13 days after initiation of topical exposure of female BALB/c strain mice to chemical allergen, or to vehicle alone. The frequency of intracellular cytokine (IL-4 and IFN-gamma)-positive CD4+ and CD8+ lymphocytes was enumerated by flow cytometry. The relative contribution of CD4+ and CD8+ cells to cytokine secretion profiles was assessed by negative selection. RESULTS: Exposure to allergen resulted in an increased frequency of both IFN-gamma+ CD4+ and CD8+ lymphocytes, although there were no marked differences between trimellitic anhydride (TMA)- and 2,4-dinitrochlorobenzene (DNCB)-activated lymph node cells. Treatment with TMA induced approximately five times as many IL-4+ CD4+ cells as did exposure to DNCB. This pattern of cytokine staining was also observed for a further pair of contact and respiratory allergens; respectively, formalin and fluorescein isothiocyanate. CONCLUSION: These data demonstrate that the divergent immune responses induced in mice by different classes of chemical allergen are independent of changes in the frequency of IFN-gamma+ cells, but are associated with differential frequencies of IL-4-expressing CD4+ T cells.     

The effect of disodium cromoglycate (DSCG) on in vitro proliferation of CD4+, CD8+, and CD19+ cell populations derived from allergic and healthy donors

The effect of disodium cromoglycate (DSCG) on in vitro proliferation of CD4⁺ and CD8⁺ T cells and CD19⁺ B cells, positively selected by immunomagnetic separation, was investigated. The cells were obtained from allergic patients with moderate serum IgE levels and mild to moderate atopic dermatitis, and healthy controls. The different cell subfractions were stimulated with mitogens or specific allergens, as well as cell supernatants from the lymphoblastoid B- (RPMI 8866) and T-hybridoma (166 A₂) cell lines. Proliferative responses of T- and B-cell subsets stimulated with mitogens together with recombinant interleukin-2 (rIL-2) or accessory cells (AC) could be inhibited by DSCG. In allergic individuals, significant allergen-specific stimulation could be observed in the CD8-depleted peripheral blood mononuclear cell (PBMC) fractions. Isolated CD4⁺ T cells, without AC or IL-2, could also be stimulated with specific allergen, but the responses were rather low. DSCG inhibited, concentration dependently, all allergen-induced responses. Interestingly, only atopic derived CD4⁺ and CD8⁺ T cells were stimulated by soluble low-affinity IgE receptor (Fc?RII/sCD23) and IgE binding factor (IgEBF), including IgE enhancing factor, present in culture supernatants from RPMI 8866 and 166 A₂, respectively. These responses were also inhibited by DSCG. This was in contrast to the amplifying effect of DSCG on spontaneously proliferating RPMI 8866 and 166 A₂ cells, cultured in fresh cRPMI 1640 medium without sCD23 and IgE enhancing factor. Our results show that DSCG delivers an inhibitory signal or signals to PBMC subpopulations expressing Fc?RII/sCD23, either upregulated by phytohemagglutinin in normal and atopic cells, or by allergens or sCD23 in atopic cells. The findings suggest that sCD23 in supernatants or in serum may reverse the general inhibitory mode of DSCG.     

CD137 ligand prevents the development of T-helper type 2 cell-mediated allergic asthma by interferon-γ-producing CD8+ T cells

BACKGROUND: Allergic asthma is a T-helper type 2 (Th2) cell-mediated chronic disease that is characterized by airway hyperreactivity (AHR) and chronic eosinophilic airway inflammation. Several studies suggest co-stimulatory molecules like CD137 as potential targets for therapeutic interventions in allergic airway disease. Recently, we could show in a murine asthma model that administration of an agonistic antibody against the receptor of the co-stimulatory molecule CD137 prevented and even reversed an already-established asthma phenotype. OBJECTIVE: The purpose of this study was to analyse the effect of stimulation of the CD137 ligand by a monoclonal antibody (CD137L mAb). METHODS: To induce an asthma-like phenotype, BALB/c mice were sensitized to ovalbumin (OVA), followed by an intrapulmonary allergen challenge. Anti-CD137L or control mAb were applied 1 day before OVA immunization or after the asthma phenotype was already established. RESULTS: Stimulation of the CD137L instead of the receptor by CD137L mAb prevents the development of an asthma-like phenotype but does not reverse established disease. While the receptor-mediated effect is partly mediated by anergy of CD4(+) T cells and partly by induction of IFN-gamma-producing CD8(+) T cells, the effect of the CD137L mAb is completely dependent on IFN-gamma-producing CD8(+) T cells: blockade of IFN-gamma and depletion of CD8(+) T cells fully abrogated the observed protective effect. In vitro experiments showed that the anti-CD137L mAb ligates directly to CD8(+) T cells and induces the generation of IFN-gamma by this cell population. CONCLUSION: Our results demonstrate that anti-CD137L mAb prevents disease development via IFN-gamma-producing CD8(+) T cells but is inferior to stimulation of the receptor that reverses established disease by a mechanism including CD4(+) T cell anergy.     

Dendritic cells expand antigen-specific Foxp3+CD25+CD4+ regulatory T cells including suppressors of alloreactivity

Summary: Thymic derived naturally occurring CD25⁺CD4⁺ T regulatory cells (Tregs) suppress immune responses, including transplantation. Here we discuss the capacity of dendritic cells (DCs) to expand antigen‐specific Tregs, particularly polyclonal Tregs directed to alloantigens. Initial studies have shown that mature DCs are specialized antigen‐presenting cells (APCs) for expanding antigen‐specific CD25⁺ CD4⁺ Tregs from TCR transgenic mice. When triggered by specific antigen, these Tregs act back on immature DCs to block the upregulation of CD80 and CD86 costimulatory molecules. More recently, DCs have been used to expand alloantigen‐specific CD25⁺CD4⁺ Tregs from the polyclonal repertoire in the presence of interleukin‐2 (IL‐2). Allogeneic DCs are much more effective than allogeneic spleen cells for expanding CD25⁺CD4⁺ Tregs. The DC‐expanded Tregs continue to express high levels of Foxp3, even without supplemental IL‐2, whereas spleen cells poorly sustain Foxp3 expression. When suppressive activity is tested, relatively small numbers of DC‐expanded CD25⁺CD4⁺ Tregs exert antigen‐specific suppression in the mixed leukocyte reaction (MLR), blocking immune responses to the original stimulating strain 10 times more effectively than to third party stimulating cells. DC‐expanded Tregs also retard graft versus host disease (GVHD) across full major histocompatibility complex (MHC) barriers. In vitro and in vivo, the alloantigen‐specific CD25⁺CD4⁺ Tregs are much more effective suppressors of transplantation reactions than polyclonal populations. We suggest that the expansion of Tregs from a polyclonal repertoire via antigen‐presenting DCs will provide a means for antigen‐specific control of unwanted immune reactions.     

Type I interferon supports primary CD8+ T-cell responses to peptide-pulsed dendritic cells in the absence of CD4+ T-cell help

CD8(+) T-cell responses to non-pathogen, cell-associated antigens such as minor alloantigens or peptide-pulsed dendritic cells (DC) are usually strongly dependent on help from CD4(+) T cells. However, some studies have described help-independent primary CD8(+) T-cell responses to cell-associated antigens, using immunization strategies likely to trigger natural killer (NK) cell activation and inflammatory cytokine production. We asked whether NK cell activation by MHC I-deficient cells, or administration of inflammatory cytokines, could support CD4(+) T-cell help-independent primary responses to peptide-pulsed DC. Injection of MHC I-deficient cells cross-primed CD8(+) T-cell responses to the protein antigen ovalbumin (OVA) and the male antigen HY, but did not stimulate CD8(+) T-cell responses in CD4-depleted mice; hence NK cell stimulation by MHC I-deficient cells did not replace CD4(+) T-cell help in our experiments. Dendritic cells cultured with tumour necrosis factor-α (TNF-α) or type I interferon-α (IFN-α) also failed to prime CD8(+) T-cell responses in the absence of help. Injection of TNF-α increased lymph node cellularity, but did not generate help-independent CD8(+) T-cell responses. In contrast, CD4-depleted mice injected with IFN-α made substantial primary CD8(+) T-cell responses to peptide-pulsed DC. Mice deficient for the type I IFN receptor (IFNR1) made CD8(+) T-cell responses to IFNR1-deficient, peptide-pulsed DC; hence IFN-α does not appear to be a downstream mediator of CD4(+) T-cell help. We suggest that primary CD8(+) T-cell responses will become help-independent whenever endogenous IFN-α secretion is stimulated by tissue damage, infection, or autoimmune disease.     

STAT6 deficiency in a mouse model of allergen-induced airways inflammation abolishes eosinophilia but induces infiltration of CD8+ T cells

BACKGROUND: The TH2-type cytokines have been reported to contribute to the asthmatic response. STAT6 has an essential role in IL-4 signalling and in production of TH2 cytokines from T cells and is involved in IgE and IgG1 responses after nematode infections, indicating that STAT6 has an important role in allergic diseases. OBJECTIVE: In this study we investigated the effects of STAT6 deficiency on allergen-induced airways inflammation in mice. METHODS: Both ovalbumin (OVA)-sensitized STAT6 deficient (STAT6-/-) mice and wild-type C57BL/6 mice were challenged with aerosolized OVA. Changes in inflammatory cell infiltration and cytokine levels in lung tissue as well as serum immunoglobulin levels were analysed in OVA-challenged STAT6-/- and wild-type mice. RESULTS: The eosinophilia and lung damage normally resulting from aeroallergen challenge were not seen in STAT6-/- mice. Expression of TH2 cytokines (IL-4 and IL-5) in the lung tissue as well as IgE and IgG1 responses after OVA challenge were profoundly reduced in STAT6-/- mice, whereas expression of IFNgamma was the same in STAT6-/- mice and wild-type mice after OVA challenge. Immunocytochemical analysis of T cells showed the infiltration of CD4+ T cells but not CD8+ T cells increased into the lung of wild-type mice after OVA challenge. However, the OVA-exposed STAT6-/- mice demonstrated the infiltration of both CD4+ T cells and CD8+ T cells with a significant increase in percentage and total number of CD8+ T cells compared with OVA-exposed wild-type mice. CONCLUSION: These results indicate that factors which signal through STAT6 are important regulators of eosinophilia of allergic airway inflammation, regulating TH2-type cytokine production both in CD4+ T cells and CD8+ T cells.     

Multiple roles for CD4+ T cells in anti-tumor immune responses

Summary: Our understanding of the importance of CD4⁺ T cells in orchestrating immune responses has grown dramatically over the past decade. This lymphocyte family consists of diverse subsets ranging from interferon-γ (IFN-γ)-producing T-helper 1 (Th1) cells to transforming growth factor-β (TGF-β)-secreting T-regulatory cells, which have opposite roles in modulating immune responses to pathogens, tumor cells, and self-antigens. This review briefly addresses the various T-cell subsets within the CD4⁺ T-cell family and discusses recent research efforts aimed at elucidating the nature of the 'T-cell help' that has been shown to be essential for optimal immune function. Particular attention is paid to the role of Th cells in tumor immunotherapy. We review some of our own work in the field describing how CD4⁺ Th cells can enhance anti-tumor cytotoxic T-lymphocyte (CTL) responses by enhancing clonal expansion at the tumor site, preventing activation-induced cell death and functioning as antigen-presenting cells for CTLs to preferentially generate immune memory cells. These unconventional roles for Th lymphocytes, which require direct cell-to-cell communication with CTLs, are clear examples of how versatile these immunoregulatory cells are.     

Defective suppression of Th2 cytokines by CD4+CD25+ regulatory T cells in birch allergics during birch pollen season

BACKGROUND: CD4(+)CD25+ regulatory T cells suppress proliferation and cytokine production by human T cells both to self-antigens and exogenous antigens. Absence of these cells in human newborns leads to multiple autoimmune and inflammatory disorders together with elevated IgE levels. However, their role in human allergic disease is still unclear. OBJECTIVE: This study aimed to evaluate the capacity of CD4(+)CD25+ regulatory T cells to suppress proliferation and cytokine production outside and during birch-pollen season in birch-allergic patients relative to non-allergic controls. METHODS: CD4+ cells were obtained from blood of 13 birch-allergic patients and six non-allergic controls outside pollen season and from 10 birch-allergic patients and 10 non-allergic controls during birch-pollen season. CD25+ and CD25- fractions were purified with magnetic beads and cell fractions, alone or together in various ratios, were cultured with antigen-presenting cells and birch-pollen extract or anti-CD3 antibody. Proliferation and levels of IFN-gamma, IL-13, IL-5 and IL-10 were measured by thymidin incorporation and ELISA, respectively. Numbers of CD25+ cells were analysed by flow cytometry. RESULTS: CD4(+)CD25+ regulatory T cells from both allergics and non-allergics potently suppressed T cell proliferation to birch allergen both outside and during birch-pollen season. However, during season CD4(+)CD25+ regulatory T cells from allergic patients but not from non-allergic controls were defective in down-regulating birch pollen induced IL-13 and IL-5 production, while their capacity to suppress IFN-gamma production was retained. In contrast, outside pollen season the regulatory cells of both allergics and non-allergic controls were able to inhibit T-helper 2 cytokine production. CONCLUSION: This is the first study to show differential suppression of Th1 and Th2 cytokines, with CD4(+)CD25+ regulatory T cells from birch-pollen-allergic patients being unable to down-regulate Th2, but not Th1 responses during birch-pollen season.     

CD4+CD25+ T cells regulate the intensity of hypersensitivity responses to peanut, but are not decisive in the induction of oral sensitization

BACKGROUND: Naturally occurring CD4+CD25+ regulatory T cells (Tregs) play a critical role in the maintenance of self-tolerance and it has been suggested that these Tregs may also be involved in preventing allergic disease. OBJECTIVE: The precise role of CD4+CD25+ T cells in the regulation of allergic responses to mucosal antigens remains to be elucidated. In the present study, it was investigated whether CD4+CD25+ T cells are involved in the induction of oral tolerance and whether they play a role in controlling hypersensitivity responses to food proteins. METHODS: CD4+CD25+ T cells were depleted with PC61 mAb before the induction of low dose oral tolerance to peanut extract (PE). In addition, CD4+CD25+ T cell depletion was performed during sensitization or before oral challenge, using a C3H/HeOuJ mouse model of allergic sensitization to peanut. RESULTS: Oral tolerance to PE could not be induced in CD4+CD25+ T cell-depleted mice. However, CD4+CD25+ T cell depletion during long-term exposure to PE alone did not result in allergic sensitization. In sensitized mice, anti-CD25 treatment during oral exposure resulted in higher levels of PE-specific IgE and increased mast cell degranulation upon an oral challenge. In contrast, anti-CD25 treatment of PE-sensitized mice before oral challenges did not affect the level of mast cell degranulation. CONCLUSION: These results indicate that CD4+CD25+ Tregs are involved in maintaining tolerance to oral antigens and regulate the intensity of an IgE-mediated food hypersensitivity response, but are not crucial in preventing sensitization. Accordingly, CD4+CD25+ Tregs may represent a potential tool for the treatment of food allergic disorders.     

Murine Stress-triggered Abortion is Mediated by Increase of CD8+ TNF-α+ Decidual Cells via Substance P

PROBLEM: Stress is known to induce abortions in mice and humans. Increased levels of abortogenic type 1 helper T-cell cytokines and decreased levels of pregnancy protective cytokines could be linked to stress-triggered embryonic loss. Stress promotes neurotransmitter substance P (SP) release in tissues. SP increases the production of decidual tumor necrosis factor (TNF)-alpha, whereby the phenotype of these TNF-alpha-producing cells is hypothetical. The objective of the present study was to identify decidual TNF-alpha-producing cell populations that are involved in stress-induced murine abortion. METHOD: DBA/2J-mated CBA/J female mice were exposed to ultrasonic sound stress on day 5.5 of pregnancy. The mice were randomized and half were treated with the SP NK1-receptor antagonist (SP-RA) RP 67580 (200 microg/mouse). Frequency and cytokine profile of CD8+ cells were evaluated by immunohistochemistry and flow cytometry. Degranulation of uterine mast cells was examined histologically. RESULTS: On day 13.5 of pregnancy, the uteri were removed and the resorption rate was calculated. A mean resorption rate of 38.4% was detected in stressed mice (n = 10) compared to 13.1% in non-stressed control mice (n = 11, P < 0.01). Injection of SP-RA decreased the abortion rate to 18.4% in stressed mice (n = 19, P < 0.01). Flow cytometry revealed a stress-related increase of TNF-alpha+/CD8+ decidual T cells, which could be abrogated by SP-RA (P < 0.05). No significant differences could be observed in numbers of mast cells and total CD8+ cells in situ. CONCLUSION: Our data suggest that stress-triggered abortion is mediated by SP, and SP receptor blockade abrogates stress-triggered abortion via reduced production of TNF-alpha by CD8+ T cells.