Effect of Acupuncture on Cytokine Levels in Persons with Multiple Sclerosis: A Randomized Controlled Trial.

Background: Cytokines have been found to play a role in the disease activity of multiple sclerosis (MS). Previous studies indicate that acupuncture can affect cytokine levels in persons with other inflammatory diseases. Objectives: The aim of this study is to investigate the effect of acupuncture on cytokine levels and health-related quality of life (HRQoL) in persons with MS. Materials and Methods: A single-blind, randomized controlled trial was performed. Participants (n = 66) were randomized into three groups (real acupuncture, sham acupuncture, and reference). Participants in the real acupuncture and sham groups received six treatments during a period of 4 weeks. The serum levels of 11 pro- and anti-inflammatory cytokines (IFNγ, IL-1ß, IL-6, IL-8, IL-12p70, IL-13, TNFα, IL-10, IL-4, IL-2, and IL-17A) were assessed at baseline, after 2 and 4 weeks of treatment, and 4 weeks after the final treatment. Changes in HRQoL were assessed using the Functional Assessment of Multiple Sclerosis questionnaire. Results: No statistically significant differences in plasma levels between the three groups were seen for either of the cytokines, nor were there any differences between the groups for HRQoL. Conclusions: In this study, the authors could not demonstrate that a 4-week acupuncture treatment had a measurable effect on the plasma levels of seven selected cytokines or on HRQoL among people with MS. The trial was registered with the ISRCTN registry as ISRCTN34352011.

Dexamethasone/1alpha-25-dihydroxyvitamin D3-treated dendritic cells suppress colitis in the SCID T-cell transfer model.

Autoantigen-presenting immunomodulatory dendritic cells (DCs) that are used for adoptive transfer have been shown to be a promising therapy for a number of autoimmune diseases. We have previously demonstrated that enteroantigen-pulsed DCs treated with interleukin-10 (IL-10) can partly protect severe combined immunodeficient (SCID) mice adoptively transferred with CD4+ CD25(-) T cells from the development of wasting disease and colitis. We therefore established an in vitro test that could predict the in vivo function of DCs and improve strategies for the preparation of immunomodulatory DCs in this model. Based on these in vitro findings, we here evaluate three methods for DC generation including short-term and long-term IL-10 exposure or DC exposure to dexamethasone in combination with vitamin D3 (Dex/D3). All DCs resulted in lower CD4+ CD25(-) T-cell enteroantigen-specific responses in vitro, but Dex/D3 DCs had the most prominent effect on T-cell cytokine secretion. In vivo, Dex/D3 DCs most efficiently prevented weight loss and gut pathology upon CD4+ CD25(-) T-cell transfer in SCID mice, although the effect on gut pathology was antigen independent. Our data in the SCID T-cell transfer model illustrate some correlation between in vitro and in vivo DC function and document that prevention of experimental inflammatory bowel disease by transfer of immunosuppressive DCs is possible.

Genome-wide expression profiling during protection from colitis by regulatory T cells.

BACKGROUND: In the adoptive transfer model of colitis it has been shown that regulatory T cells (Treg) can hinder disease development and cure already existing mild colitis. The mechanisms underlying this regulatory effect of CD4(+)CD25(+) Tregs are not well understood. METHODS: To identify pathways of importance for immune regulation in protected mice we studied the genome-wide expression profile in the inflamed rectum of SCID mice with CD4(+) T cell transfer colitis and in the uninflamed rectum of mice protected from colitis by Treg cells. We used DNA microarray technology (Affymetrix GeneChip Mouse Genome 430 2.0 Array), which enabled an analysis of a complete set of RNA transcript levels in each sample. Array results were confirmed by real-time reverse-transcriptase polymerase chain reaction (RT-PCR). RESULTS: Data were analyzed using combined projections to latent structures and functional annotation analysis. The colitic samples were clearly distinguishable from samples from normal mice by a vast number of inflammation- and growth factor-related transcripts. In contrast, the Treg-protected animals could not be distinguished from either the normal BALB/c mice or the normal SCID mice. mRNA expression profiles of cytokine, chemokine, and growth factor genes were significantly altered in colitic as opposed to noncolitic mice. In particular, the transcription factors STAT3, GATA2, and NFkappaB, the cytokine IL1beta, and the chemokine receptors CXCR3 and CCR1 as well as their ligands all seemingly play central roles in the inflammatory processes. CONCLUSIONS: We suggest that these molecules alone or in combination could be future therapeutic targets.

Identifying multiple tumor-specific epitopes from large-scale screening for overexpressed mRNA.

The rationale of a T-cell epitope-based approach to cancer treatment is primarily rooted in the hypothesis that CD8(+) cytotoxic T cells (CTLs) can be manipulated to specifically identify and kill cancer cells. A solid understanding of CTL specificity and activation is a fundamental requirement for tumor immunotherapy. The means to identify tumor-specific CTL epitopes and to monitor corresponding CTL responses are important enabling technologies. Recent advances in these enabling technologies include their ability to exploit genomic, transcriptomic and proteomic information. These advances constitute new opportunities, which will enable approaches to tumor immunotherapy that encompass both human diversity and tumor heterogeneity, increase the efficacy of tumor immunotherapy and potentially provide the opportunity for individualized therapy.

Chemokines involved in protection from colitis by CD4+CD25+ regulatory T cells.

Chemokines are small proteins involved in the direction of migration of immune cells both during normal homeostasis and inflammation. Chemokines have been implicated in the pathology of many different inflammatory disorders and are therefore appealing therapeutic targets. Using a chemokine/chemokine receptor-specific gene expression profiling system of 67 genes, the authors have determined the expression profile of chemokine and chemokine receptor genes in the rectum of colitic mice and in mice that have been protected fromcolitis by CD4CD25 regulatory T cells. In mice protected from colitis, the authors found down regulation of the mRNA expression of the inflammatory chemokine receptors CCR1 and CXCR3 and their ligands CXCL9, CXCL10, CCL5, and CCL7. Also the transcripts for CCR9, CCL25, CCL17, and CXCL1 are found down regulated in protected compared with colitic animals. In addition, the authors' results suggest that CCL20 is used by CCR6 regulatory T cells in the complex process of controlling colitis because transcripts for this chemokine were expressed to a higher level in protected animals. The chemokine pathways identified in the present study may be of importance for the development of new targets for anti-inflammatory treatment strategies in human inflammatory bowel disease.

CXC chemokine receptor 3 expression increases the disease-inducing potential of CD4+ CD25- T cells in adoptive transfer colitis.

BACKGROUND: CD4CD25 T cells induce severe colitis when injected into immunodeficient recipients. The migration of disease-inducing cells to the bowel is controlled by adhesion molecules and chemotactic proteins. Chemokine receptors expressed on the T cells are therefore potential targets for anti-inflammatory therapy in inflammatory bowel disease. In this study, we have investigated the role of the chemokine receptor CXCR3 in the development of chronic colitis in a murine model. METHOD: Expression of CXCR3 on CD4 T cell from normal and colitic mice was assessed by flow cytometry. Development of colitis was followed after transfer of either normal or CXCR3CD4CD25T cell into immunodeficient host. In addition, the ability of regulatory T cell to function in vivo in the absence of CXCR3 was tested. RESULTS: We find CXCR3 to be expressed on 80% to 90% of CD4 T cells isolated from colitic mice compared with only 4% to 10% of CD4 T cells in normal naïve mice. Injecting CD4CXCR3CD25 T cells into immunodeficient hosts results in an ameliorated form of colitis with a lack of clinical symptoms, suggesting that CXCR3 expression is important for enteroantigen priming of CD4 T cells and/or subsequent migration into the gut wall. In contrast, CXCR3 expression does not affect the function of regulatory T cells because CXCR3 regulatory T cells are just as capable as their wild-type counterpart of controlling disease development. The diminished disease-inducing capability of CXCR3 T cells is not caused by the absence of enteroantigen specificity; we also tested the enteroantigen-specific proliferative ability of CD4CD25 T cells from CXCR3 mice in vitro and found that they respond even more strongly than wild-type cells. CONCLUSIONS: The present data indicate that CXCR3 plays an important role in controlling the migration of disease-inducing CD4CD25 T cells into the gut wall. In contrast, lack of CXCR3 expression by regulatory T cells does not compromise their function in this model of colitis.

Immunogenicity of HLA Class I and II Double Restricted Influenza A-Derived Peptides.

The aim of the present study was to identify influenza A-derived peptides which bind to both HLA class I and -II molecules and by immunization lead to both HLA class I and class II restricted immune responses. Eight influenza A-derived 9-11mer peptides with simultaneous binding to both HLA-A*02:01 and HLA-DRB1*01:01 molecules were identified by bioinformatics and biochemical technology. Immunization of transgenic HLA-A*02:01/HLA-DRB1*01:01 mice with four of these double binding peptides gave rise to both HLA class I and class II restricted responses by CD8 and CD4 T cells, respectively, whereas four of the double binding peptides did result in HLA-A*02:01 restricted responses only. According to their cytokine profile, the CD4 T cell responses were of the Th2 type. In influenza infected mice, we were unable to detect natural processing in vivo of the double restricted peptides and in line with this, peptide vaccination did not decrease virus titres in the lungs of intranasally influenza challenged mice. Our data show that HLA class I and class II double binding peptides can be identified by bioinformatics and biochemical technology. By immunization, double binding peptides can give rise to both HLA class I and class I restricted responses, a quality which might be of potential interest for peptide-based vaccine development.

Colitic scid mice fed Lactobacillus spp. show an ameliorated gut histopathology and an altered cytokine profile by local T cells.

BACKGROUND: Scid mice transplanted with CD4 T blast cells develop colitis. We investigated if the disease was influenced in colitic mice treated with antibiotic and fed Lactobacillus spp. METHODS: Colitic scid mice were treated for 1 week with antibiotics (vancomycin/meropenem) followed or not followed by a 3-week administration of Lactobacillus reuteri DSM-12246 and Lactobacillus rhamnosus 19070-2 at 2x10 live bacteria/mouse/24 hours. After 12 weeks, the rectums were removed for histology, and CD4 T cells from the mesenteric lymph nodes (MLN) were polyclonally activated for cytokine measurements. RESULTS: Irrespective of no treatment or treatments with antibiotics and probiotics, all mice transplanted with T cell blasts lost 10% of their body weight during the 12-week experimental period, whereas the nontransplanted mice had a 10% weight increase (P<0.001). All mice treated with antibiotics but not fed probiotics showed severe gut inflammation, whereas only 2 of the 7 mice fed probiotics showed signs of severe colitis (P<0.05). MLN-derived CD4 T cells from this latter group of mice showed lower levels of interleukin-4 secretion (P<0.05) and a tendency to higher interferon-gamma production than mice not fed probiotics. CONCLUSIONS: Our data suggest that probiotics added to the drinking water may ameliorate local histopathological changes and influence local cytokine levels in colitic mice but not alter the colitis-associated weight loss.

[The influence of melatonin on the immune system and cancer]. / Melatonins indvirkning på immunsystem og cancer

Melatonin has been shown to play a fundamental part in neuroimmunomodulation. Besides regulating the circadian rhythm it works as a natural antioxidant with immune stimulatory and anti-cancer properties. Melatonin is a regulator of haemopoiesis and modifies various cells and cytokines of the immune system. Also, melatonin elicits oncostatic properties in a variety of different tumour cell lines. A number of studies have documented that when given in combination with chemo-therapy to patients with disseminated disease, melatonin increases the overall one-year survival and reduces toxic side effects.

Induction of regulatory dendritic cells by dexamethasone and 1alpha,25-Dihydroxyvitamin D(3).

Dendritic cells (DC) modulated to induce T cell hyporesponsiveness have promising potential in immunotherapy of autoimmune disorders and for the prevention of allograft rejection. While studying the effect of immunosuppressive agents on the maturation of DC we found that 1alpha,25-Dihydroxyvitamin D(3) the active form of Vitamin D(3) (D(3)) in combination with dexamethasone (Dex) has a synergistic effect on LPS-induced maturation of DC. Monocyte-derived DCs cultured with D(3) and Dex during LPS-induced maturation have a low stimulatory effect on allogeneic T cells comparable with that of immature DCs. But in contrast to immature DCs, D3/Dex exposed DCs secrete IL-10 and show upregulated transcription of mRNA encoding the Ig-like inhibitory receptor ILT4. D3/Dex exposed DCs also inhibit alloreactivity and slightly enhance the degree of apoptosis in mature DCs. Thus, D(3)/Dex is an effective immunosuppressive drug combination for the induction of DCs capable of inducing T cell hyporesponsiveness.

Comparison of CTL reactivity in the spleen and draining lymph nodes after immunization with peptides pulsed on dendritic cells or mixed with Freund's incomplete adjuvant.

OBJECTIVE: To compare CTL reactivity in the spleen and the draining lymph nodes (LN) from C57BL/6 mice after immunization with self and non-self peptides pulsed on autologous dendritic cells (DC) or mixed with Freund's incomplete adjuvant (FIA). METHODS: Peptides showing high to low binding affinities for H-2 Kb/Db were emulsified in FIA or pulsed on bone marrow (BM)-derived DC and injected subcutaneously into C57BL/6 mice. Eight days later, the mice were sacrificed and cell suspensions were prepared from the spleen and draining LN. Splenocytes or LN cells were cultured for 5 days with irradiated syngeneic spleen cells (as APCs) pulsed with the appropriate peptide in vitro. 51Cr-release assay using peptide pulsed target cells was used to detect CTL reactivity. RESULTS: Both self and non-self peptides can induce specific CTL responses with the adjuvant FIA and DC. Peptide pulsed DC were found to be more effective than peptides mixed with FIA to induce specific CTL responses towards non-self peptides and can induce much stronger responses in the spleen than in the draining LN both for non-self and self peptides. Self peptides emulsified in FIA generated the strongest responses in the draining LN, whereas non-self peptides mixed with FIA generated the strongest response in the spleen. CONCLUSIONS: DC-based immunization with non-self and self peptides is more efficient than immunization based on peptides mixed with FIA. DC-based immunization focuses the CTL response towards the spleen. Immunization based on FIA focuses the response against self peptides towards the draining LN and non-self peptides towards the spleen.

Dendritic cells in peripheral tolerance and immunity.

Dendritic cells capable of influencing immunity exist as functionally distinct subsets, T cell-tolerizing and T cell-immunizing subsets. The present paper reviews how these subsets of DCs develop, differentiate and function in vivo and in vitro at the cellular and molecular level. In particular, the role of DCs in the generation of regulatory T cells is highlighted.

Enteroantigen (eAg)-binding B lymphocytes in the mouse - phenotype, distribution, function and eAg-specific antibody secretion.

Studies reporting beneficial effects of B lymphocytes in autoimmune diseases have been accumulating and a regulatory role for certain B cell subsets is hence getting more and more recognition. Recently, B cells were shown to exhibit a regulatory effect in a T cell transfer model of colitis. Here, B cells exposed to enteroantigen (eAg) ex vivo abrogated the colitogenic effect if co-transplanted with Treg-depleted (CD4+CD25-) T cells into severe combined immune deficiency (SCID) mice. These data may imply a role for B cells that bind eAg (eAg+ B cells) in the immunopathology of colitis. Here, we report the detection of a subset of eAg+ B cells, including both B2 and B1 lineages, and show that these cells are present in all peripheral lymphoid organs of the mouse including the peritoneal cavity. eAg+ B cells are far more efficient as eAg-presenting cells than unfractionated splenocytes or eAg- B cells in causing proliferation of eAg-specific T cells. In comparison with eAg- B cells, eAg+ B cells secrete a significant amount of IL-10 in vitro, suggesting an anti-inflammatory potential. Compared with wild-type B cells, B cell receptor (BCR) transgenic, hen egg lysozyme-specific B cells show inferior eAg binding and T cell stimulatory activity suggesting involvement of the BCR in eAg binding and processing. After activation of CD19(+) B cells by eAg and hybridization with hypoxanthine-aminopterin-thymidine (HAT) sensitive ×63 lymphoma cells followed by cloning at limiting dilution conditions, around 10% of the hybridoma cells secrete eAg-specific antibodies.

TH17 cell induction and effects of IL-17A and IL-17F blockade in experimental colitis.

BACKGROUND: T helper (TH) 17 cells are believed to play a pivotal role in development of inflammatory bowel disease, and their contribution to intestinal inflammation has been studied in various models of colitis. TH17 cells produce a range of cytokines, some of which are potential targets for immunotherapy. However, blockade of IL-17A alone with secukinumab was not effective in Crohn's disease. In this regard, the pathogenic impact of IL-17A versus IL-17F during intestinal inflammation is still unresolved. METHODS: Development of IFN-γ-producing, IL-17A-producing, and IL-17F-producing CD4 T cells was analyzed in the CD4CD25 T-cell transfer model of colitis at varying degrees of colitis. The pathogenic roles of IL-17A and IL-17F were investigated by treating colitic mice with neutralizing antibodies against these 2 cytokines. RESULTS: We found that colitis development was associated with an increase in IL-17A-producing TH17 cells in spleen, mesenteric lymph nodes, and lamina propria. In contrast, the relative abundance of IFN-γ-producing TH1 cell was stable in all 3 organs during progression of colitis, and the frequency of IFN-γIL-17A double-positive cells declined in spleen and mesenteric lymph node but not in lamina propria. IL-17F was coexpressed in TH17 cells and IFN-γIL-17A double positive but not in TH1 cells and its expression inversely correlated with colitis development. In vivo neutralization of both IL-17A and IL-17F ameliorated colitis in particular at early administration, whereas neutralization of IL-17A or IL-17F alone was inefficient. CONCLUSIONS: TH17 cell development correlates with colitis progression, and concurrent neutralization of their cytokine products IL-17A and IL-17F ameliorates intestinal inflammation. These findings suggest combined IL-17A and IL-17F blockade as a potential strategy in inflammatory bowel disease therapy.

B cells exposed to enterobacterial components suppress development of experimental colitis.

BACKGROUND: B cells positively contribute to immunity by antigen presentation to CD4(+) T cells, cytokine production, and differentiation into antibody secreting plasma cells. Accumulating evidence implies that B cells also possess immunoregulatory functions closely linked to their capability of IL-10 secretion. METHODS: Colitis development was followed in CD4(+) CD25(-) T cell transplanted SCID mice co-transferred with B cells exposed to an enterobacterial extract (ebx-B cells). B and T cell cytokine expression was measured by flow cytometry and enzyme-linked immunosorbent assay (ELISA). RESULTS: We demonstrate that splenic B cells exposed to ebx produce large amounts of IL-10 in vitro and express CD1d and CD5 previously known to be associated with regulatory B cells. In SCID mice transplanted with colitogenic CD4(+) CD25(-) T cells, co-transfer of ebx-B cells significantly suppressed development of colitis. Suppression was dependent on B cell-derived IL-10, as co-transfer of IL-10 knockout ebx-B cells failed to suppress colitis. Ebx-B cell-mediated suppression of colitis was associated with a decrease in interferon gamma (IFN-γ)-producing T(H) 1 cells and increased frequencies of Foxp3-expressing T cells. CONCLUSIONS: These data demonstrate that splenic B cells exposed to enterobacterial components acquire immunosuppressive functions by which they can suppress development of experimental T cell-mediated colitis in an IL-10-dependent way.

Consumption of probiotics increases the effect of regulatory T cells in transfer colitis.

BACKGROUND: Probiotics may alter immune regulation. Recently, we showed that the probiotic bacteria Lactobacillus acidophilus NCFM™ influenced the activity of regulatory T cells (Tregs) in vitro. The aim of the present work was to demonstrate if L. acidophilus NCFM™ also affects the function of Tregs in vivo. METHODS: Development of colitis after transfer of CD4+CD25- T cells and protection from colitis by Tregs was studied in immunodeficient SCID mice which were simultaneously tube-fed with L. acidophilus NCFM™ or L. salivarius Ls-33 for 5 weeks. RESULTS: Probiotic-fed SCID mice transplanted with low numbers of Tregs in addition to the disease-inducing T cells were completely protected from colitis. This was in contrast to the control group, which showed intermediate levels of inflammation. In addition, feeding with probiotics lowered serum levels of inflammatory cytokines in both colitic mice and in mice protected from colitis by Tregs. Gene expression patterns of rectum samples of protected mice that receive either one of the probiotics showed a closer resemblance to naïve SCID mice than did patterns of the control group. The mechanism of action of the probiotics appears to be an indirect effect by inducing a Treg-favorable environment rather than a direct effect on the Tregs. CONCLUSIONS: L. acidophilus NCFM™ and L. salivarius Ls-33 feeding of SCID mice increases the in vivo effect of Tregs, resulting in a gene expression pattern in the rectum resembling that of the naïve SCID mouse.

Immunological Links to Nonspecific Effects of DTwP and BCG Vaccines on Infant Mortality.

A number of mainly observational studies suggest that many African females below the age of one year die each year from the nonspecific effects of vaccination with diphtheria-tetanus toxoids and killed (whole-cell) Bordetella pertussis (DTwP). In contrast, similar studies suggest that many African females and males may have their lives saved each year by the nonspecific immunological benefits of Bacillus Calmette-Guerin (BCG) vaccination. From an immunological point of view, we hypothesise that the adverse effects of DTwP vaccine may occur because of the Th2-polarising effect of the aluminium phosphate adjuvant in the vaccine and because intramuscular administration of the vaccine may cause chronic inflammation at the site of injection. However, the Th1-polarising effect of BCG is likely to be beneficial. Sexual dimorphism affecting immune functions and vitamin A supplementation may influence both the deleterious and beneficial nonspecific effects of immunisation.

Dendritic cells modified by vitamin D: future immunotherapy for autoimmune diseases.

Dendritic cells (DCs), the most potent antigen-presenting cells of the immune system, express nuclear receptors for 1,25-dihydroxyvitamin D(3) (VD3) and they are one of its main targets. In the presence of VD3, DCs differentiate into a phenotype that resembles semimature DCs, with reduced T cell costimulatory molecules and hampered IL-12 production. These VD3-modulated DCs induce T cell tolerance in vitro using multiple mechanisms such as rendering T cells anergic, dampening of Th1 responses, and recruiting and differentiating regulatory T cells. Due to their ability to specifically target pathological T cells, VD3-modulated DCs are safe and potentially more effective alternatives to currently available immunoregulatory therapies. While a number of considerations remain, including the establishment of a reliable quality control measure to ensure the safety and efficacy of VD3-DCs in vivo and the optimal frequency, dose, and route of DC administration to achieve therapeutic effects in humans, adoptive VD3-DC transfer represents one of the most promising approaches to future treatment of autoimmune diseases.

Enteroantigen-presenting B cells efficiently stimulate CD4(+) T cells in vitro.

BACKGROUND: Presentation of enterobacterial antigens by antigen-presenting cells and activation of enteroantigen-specific CD4(+) T cells are considered crucial steps in inflammatory bowel disease (IBD) pathology. The detrimental effects of such CD4(+) T cells have been thoroughly demonstrated in models of colitis. Also, we have previously established an in vitro assay where murine enteroantigen-specific colitogenic CD4(+) CD25(-) T cells are activated by splenocytes pulsed with an enterobacterial extract. METHODS: CD4(+) CD25(-) T cells were stimulated in vitro with various kinds of enterobacterial extract-pulsed antigen-presenting cells. T-helper phenotypes were detected by flow cytometry. RESULTS: We found that enteroantigen-pulsed splenic B cells possess a significantly higher and more sustained T cell stimulatory capacity than similarly pulsed splenic dendritic cells (DCs) measured by the level of enteroantigen-specific CD4(+) CD25(-) T cell proliferation. In support of this, we observed upregulation of classic maturation markers in B cells following incubation with enterobacterial antigens. Peritoneal and mesenteric lymph node-derived B cells were equally effective as enteroantigen-presenting stimulator cells. B cells greatly expanded the number of stimulated CD4(+) T cells, which acquired a T(H) 2 phenotype. Interestingly, regulatory T cells were primarily activated by enteroantigen-pulsed B cells but not by similarly pulsed DCs. CONCLUSIONS: We conclude that B cells are superior stimulators of enteroantigen-specific CD4(+) T cells in vitro, favoring T(H) 2 polarization. Thus, enteroantigen-processing and -presentation by B cells instead of by DCs might have opposing consequences for IBD development.

Antigen-presenting cells exposed to Lactobacillus acidophilus NCFM, Bifidobacterium bifidum BI-98, and BI-504 reduce regulatory T cell activity.

BACKGROUND: The effect in vitro of six different probiotic strains including Lactobacillus acidophilus NCFM, Lactobacillus salivarius Ls-33, Lactobacillus paracasei subsp. paracasei YS8866441, Lactobacillus plantarum Lp-115, Bifidobacterium bifidum BI-504 and BI-98 was studied on splenic enteroantigen-presenting cells (APC) and CD4(+)CD25(+) T-regulatory cells (Tregs) in splenocyte-T cell proliferation assays. METHODS: Splenocytes exposed to enteroantigen +/- probiotics were used to stimulate cultured CD4(+)CD25(-) T cells to which titrated numbers of Tregs were added. Cytokine assays were performed by use of neutralizing antibodies and ELISA. RESULTS: Exposure of APCs to enteroantigens and the series of probiotic strains mentioned above did not influence the stimulatory capacity of APCs on proliferative enteroantigen-specific T cells. However, exposure to B. bifidum BI-98, BI-504 and L. acidophilus NCFM consistently reduced the suppressive activity of Tregs. The suppressive activity was analyzed using fractionated components of the probiotics, and showed that a component of the cell wall is responsible for the decreased Treg activity in the system. The probiotic-induced suppression of Treg function is not mediated by changes in APC-secretion of the inflammatory cytokines IL-6 or IL-1b. CONCLUSION: We conclude that certain probiotic strains can modify APCs to cause reduced Treg activity. This effect apparently depends on a direct APC-to-Treg cell contact. The APC-mediated suppressive effect on Treg function of certain probiotic strains may constrain the anti-inflammatory activity, which is often desired from probiotic therapy. This unexpected function of certain probiotic strains should be taken into consideration when designing adjuvant therapies with these bacteria, or when probiotic strains are selected for improvement of gut-associated inflammation like IBD.