Thus, the

primary cellular target of IL-23 in the context

Thus, the

primary cellular target of IL-23 in the context of autoimmunity is a subject of some debate. Innate lymphoid cells (ILCs) are a recently discovered family of lymphocytes being involved in early host defense, particularly at mucosal epithelial surfaces. Given the fact that RORγt-dependent ILCs (group 3 ILCs) constitutively express the IL-23-receptor, and that they have been implicated in intestinal autoimmunity, we hypothesized that ILCs could contribute to the early development of autoimmune neuroinflammation. Through systematic analysis, we detected a sizable population of Thy1+ Sca1+ ILCs in the inflamed CNS tissue. CNS-infiltrating ILCs were characterized by expression of the IL-7-receptor and production of proinflammatory IL-17 and IFN-γ. Furthermore, click here genetic fate-mapping revealed their dependence on the transcription factor RORγt. However, upon specific in vivo ablation of this cell population, we found that they do not influence the course of the disease. Over the past 5 years, the term innate lymphoid cells (ILCs) has been coined to describe a new family GDC-0068 ic50 of innate lymphocytes that lack

rearranged antigen receptors, but share phenotypic and functional characteristics with cells of the adaptive immune system. Beside the well-characterized populations of natural killer (NK) cells and lymphoid tissue inducer cells, several subtypes of ILCs see more have recently been described, both in mouse and human (reviewed in [1, 2]). RORγt+ ILCs, which depend on the retinoic

receptor related orphan receptor (RORγt) for their development, constitutively express the IL-23 receptor and are able to produce pro-inflammatory cytokines such as IL-17 and IL-22, similar to T cells of the TH17 lineage [3]. In contrast, the so-called group 2 ILCs (also known as nuocytes or natural helper cells) were discovered as innate producers of IL-5 and IL-13 [4, 5]. Very recently, a group of researchers has proposed a unifying nomenclature for ILCs, which would divide these cells into three subgroups based on their phenotypic and functional profile [6]. RORγt+ ILCs (group 3 ILCs) are best known for their nonredundant role during formation of secondary lymphoid tissues in embryonic development [7], but they also have been suggested to be critical in early host defense in different mouse models of infection, in particular in the intestine. For example, after infection with Citrobacter rodentium, CD4+ Thy1+ ILCs respond by production of IL-22 required for bacterial clearance [8]. Furthermore, Nkp46+ ILCs have been implicated in the maintenance of intestinal homeostasis [9, 10]. In 2010, another unexpected role was attributed to RORγt+ ILCs: Powrie and colleagues identified a Lineage− Thy1+ Sca1+ population of ILCs as the main mediator of innate IL-23-dependent gut inflammation in Rag−/− mice after infection with Helicobacter hepaticus [11].

albicans and 12 C parapsilosis strains to human buccal epithelia

albicans and 12 C. parapsilosis strains to human buccal epithelial cells and the expression of fungal cell surface carbohydrates using lectin histochemistry. Adherence assays were carried out by incubating epithelial cells in yeast suspensions (107 cells ml−1) and peroxidase conjugated lectins (Con A, WGA, UEA I and PNA at 25 μg ml−1) were used for lectin histochemistry. The results showed that adherence was overall greater for C. albicans than for C. parapsilosis (P < 0.01) and that the individual strain differences correlated with a high content of cell surface α-l-fucose residues as indicated by the UEA I staining

pattern. Based on the saccharide specificity of the lectins used, these results suggest that l-fucose residues on cell surface glycoconjugates may represent recognition Adriamycin concentration molecules for interactions between the yeast strain studied and the host (r = 0.6985, P = 0.0045). In addition, our results indicated the presence of α-d-glucose/α-d-mannose, N-acetyl-d-glucosamine/N-acetylneuraminic acid and d-galactose/N-acetyl-d-galactosamine in fungal cell wall. “
“Cutaneous Malassezia is an exacerbating factor in patients with atopic dermatitis. We analysed the Malassezia microbiota of adult patients with head and neck atopic dermatitis of different severities (mild, moderate and severe). Of the nine human-associated Malassezia species, the number detected was similar

(3.5–4.2 species per case) among the members of all severity groups. However, the ratio of the two major Malassezia species, M. globosa and Temsirolimus concentration M. restricta, was different in the severe group. “
“Volatile Dabrafenib mw metabolites of Aspergillus fumigatus and Candida species can be detected by gas chromatography/mass spectrometry (GC/MS). A multi-capillary column – ion mobility spectrometer (MCC-IMS) was used in this study to assess volatile organic compounds (VOCs) in the headspace above A. fumigatus and the four Candida species Candida albicans, Candida parapsilosis, Candida glabrata and Candida tropicalis in an innovative approach, validated for A. fumigatus and C. albicans by GC/MS analyses. For the detection of VOCs, a special stainless steel

measurement chamber for the microbial cultures was used. The gas outlet was either attached to MCC-IMS or to adsorption tubes (Tenax GR) for GC/MS measurements. Isoamyl alcohol, cyclohexanone, 3-octanone and phenethylalcohol can be described as discriminating substances by means of GC/MS. With MCC-IMS, the results for 3-octanone and phenethylalcohol are concordant and additionally to GC/MS, ethanol and two further compounds (p_0642_1/p_683_1 and p_705_3) can be described. Isoamyl alcohol and cyclohexanone were not properly detectable with MCC-IMS. The major advantage of the MCC-IMS system is the feasibility of rapid analysis of complex gas mixtures without pre-concentration or preparation of samples and regardless of water vapour content in an online setup.

Background: Listeria monocytogenes is a rare cause of peritonitis

Background: Listeria monocytogenes is a rare cause of peritonitis, usually occurring in the setting of cirrhosis or immunosuppression. Palbociclib There are 12 published cases of Listeria monocytogenes peritoneal

dialysis peritonitis in the literature. The 10 patients on continuous ambulatory peritoneal dialysis and 2 with unknown method of peritoneal dialysis were all treated with intravenous or intraperitoneal antibiotics. We report a case occurring in an automated peritoneal dialysis patient, successfully treated with oral antibiotics. Methods: An 87 year old, non-immunosuppressed end-stage renal failure patient on automated peritoneal dialysis, presented with abdominal pain, bloating and diarrhoea after consuming a meal of sushi. She was systemically well and commenced

on empiric outpatient antimicrobial therapy with intraperitoneal vancomycin 2 g and gentamicin 80 mg. Peritoneal dialysate gram stain demonstrated gram positive rods, subsequently culture positive for Listeria monocytogenes. Her antibiotic therapy was changed to amoxicillin 1 g every eight hours orally and she completed total of 22 days of therapy. Her abdominal discomfort resolved and her peritoneal dialysate Erlotinib price cleared. Results: Repeat dialysate culture one week following completion of antibiotic therapy confirmed resolution of peritonitis. Conclusions: Oral antimicrobial therapy may be effective in treatment of Listeria monocytogenes peritoneal dialysis peritonitis in the systemically well patient. 292 UNUSUAL BLEEDING

IN THIN GLOMERULAR BASEMENT MEMBRANE DISEASE A LEE, J SEVASTOS St Vincent’s Hospital, Sydney, NSW, Australia Aim: We present a case of thin glomerular basement membrane (GBM) disease with unusual manifestations of haematuria, haemoptysis and peritoneal bleeding. Background: Thin GBM disease is caused by a defect of collagen, occasionally Farnesyltransferase associated with loin pain haematuria syndrome. It is considered a disease affecting only the renal tract. There are only few case reports of haemoptysis associated with this condition but there is no literature suggesting bleeding elsewhere. Methods: A young patient presented age 16 with recurrent severe abdominal pain over many months. Laparoscopy for appendicectomy demonstrated no appendicitis but a small amount of blood was found in the pelvis. She subsequently developed intermittent macroscopic haematuria. Cystoscopy showed mild to moderate mucosal bladder erythema and trabeculation, possibly interstitial cystitis. Repeat laparoscopy again noted the presence of free blood in the pelvis. There was no endometriosis and sexually transmitted infection screen was negative. Endoscopy revealed moderate chronic fundal gastritis and colonoscopy to investigate rectal bleeding found a rectal hyperplastic polyp.

Here we developed the first mathematical model of peripheral Treg

Here we developed the first mathematical model of peripheral Treg-cell homeostasis, incorporating secondary lymphoid organs as separate entities and encompassing factors determining the size of the Treg-cell

population, namely thymic output, homeostatic proliferation, peripheral conversion, transorgan migration, apoptosis, and the Tnaive-cell population. Quantitative data were collected by monitoring Tnaive-cell homeostasis and Treg-cell rebound after selective in vivo depletion of Treg cells. Our model predicted the previously unanticipated possibility that Treg cells regulate migration of Tnaive cells between spleen and peripheral lymph nodes (LNs), whereas migration Talazoparib research buy of Treg cells between Tamoxifen manufacturer these organs can largely be neglected. Furthermore, our simulations suggested that peripheral conversion significantly contributed to the maintenance of the Treg-cell population, especially in LNs. Hence, we provide the first estimation of the peripheral Treg-cell conversion rate and propose additional facets of Treg-cell-mediated

immune regulation that may previously have escaped attention. “
“Stimulation of neutrophils may potentiate immunity to Leishmania major. CpG-containing oligodeoxynucleotide (ODN) has immune stimulatory effects and has been suggested as adjuvants and therapeutics to potentiate efficacy of vaccines and treatments against leishmaniasis. Here, we examined the stimulatory effect of synthetic ODN containing CpG motifs class A and

B on cytokine production by neutrophils. Neutrophils from healthy donors responded to CpG-ODN type A, but not to class B, with secretion of IL-8 and following GM-CSF pretreatment with TNF-α production. To test whether neutrophil responses were altered in cutaneous leishmaniasis (CL) and to better understand the role of neutrophils in susceptibility and resistance to disease, we evaluated cytokine responses in GM-CSF preconditioned Axenfeld syndrome neutrophils from asymptomatic (Leishmanin skin test positive, LST+) and nonhealing CL individuals to CpG-ODN class A and assessed the expression levels of toll-like receptors (TLR2), 4 and 9. LST+ and healthy donor, but not nonhealing CL neutrophils, responded with TNF-α secretion. Neutrophils from nonhealing CL displayed increased mRNA expression levels of TLR2, 4 and 9 compared to neutrophils from LST+ or healthy donors. Therefore, failure to cure CL is associated with reduced ability of neutrophils to secrete TNF-α and correlates with high TLR 2, 4 and 9 expressions. Cutaneous leishmaniasis (CL) is a widespread and highly endemic disease in young individuals in many parts of the Middle East and central Asia. There is no effective vaccination, and control of disease relies primarily on chemotherapy, which is expensive and can have major side effects (1) and in addition may not reduce the stigmatizing features of CL.

After 1 day of culture, IFN-γ production was consistently induced

After 1 day of culture, IFN-γ production was consistently induced by all strains, except for strains B1697 and B223, and the IFN-γ induction was significantly higher Apitolisib on day 4 compared with that on day 1 (on average 16-fold). A clear difference in IFN-γ induction was observed for the different strains tested, with strains B1697 and B223 eliciting consistently low IFN-γ induction whereas the other strains were strong inducers. The strong

IFN-γ-inducing strains also showed an increased IL-12 production, though IL-12 levels were, in all samples, below 25 pg mL−1 (data not shown). IL-13 could not be detected on day 1 and was <25 pg mL−1 on day 4. To determine the effects of lactobacilli interacting with stimulated hPBMC, αCD3/αCD28 was added to the culture and cells were cultured for 4 days. All strains inhibited IL-13 production by αCD3/αCD28-stimulated hPBMC (Fig. 4f). Strain B2261, the mixture

of strains B2261 and B633, and strain B633 alone were significantly stronger IL-13 inhibitors (on average a factor 7 inhibition) compared with the other strains tested (on average a factor 3 inhibition). There was a clear tendency of lactobacilli to inhibit IL-1β production, except for strains B1697 and B223 (Fig. 4a), while TNF-α (Fig. 4c) and IL-10 (Fig. 4b) production was increased compared with the control for most strains, except for strains B223 and CBI 118. Addition of the various Lactobacillus strains to the hPBMC had no effect on IFN-γ production, which was high in all cultures after stimulation selleck kinase inhibitor Florfenicol with αCD3/αCD28 (Fig. 4d). IL-12 (Fig. 4e) was induced by strains B1836, B2261, the mixture of B2261 and B633, B633 alone and CBI 118, which was the same group of strains that also induced

IL-12 and IFN-γ production in the unstimulated cultures. The polyclonal stimulus αCD3/αCD28 clearly induced IL-1β, IL-10, TNF-α, IFN-γ and IL-13 production compared with the unstimulated cultures. The induction of IL-10 by the strains was significantly lower in the αCD3/αCD28-stimulated cultures compared with the unstimulated cultures for the mixture of strains B2261 and B633, and strain B633. To determine the effect of the different lactobacilli on antigen-specific stimulated cultures, hPBMC of the five birch pollen-allergic patients were cultured in the presence of the major birch pollen allergen Bet v 1 and in the presence or absence of the different lactobacilli. After 8 days of culture, four stimulation conditions were compared. The restimulation condition with αCD3/αCD28 on day 7 was used to increase the amount of antigen-specific T cells in the cultures, which are still expected to be active in the culture and proliferate upon interaction with the specific antigen, Bet v 1. The addition of Bet v 1 did not result in significant differences in cytokine production profiles compared with the medium control.

To induce maturation, DCs were incubated with 10 µg/ml LPS (Sigma

To induce maturation, DCs were incubated with 10 µg/ml LPS (Sigma-Aldrich, Saint Louis, MO, USA) for 48 h. To analyse the effect of parasites on DC maturation, LPS- or IFN-γ- (10 ng/ml; BD Pharmingen) check details or IFN-γ/LPS-stimulated cells were incubated in the presence of Lm clones for 48 h. Cytospins were prepared using a cytocentrifuge

set at 100 g for 5 min. DCs were then May–Grünwald–Giemsa-stained and the percentage of infected cells and the number of intracellular parasites were determined by light microscopic analysis, after counting 100 cells per slide. Cytokines (IL-12p70, TNF-α and IL-10) were detected on cell-free 48 h culture supernatants using commercially available ELISA kits (BD optEIA; BD Biosciences). Recombinant cytokines were used to obtain standard curves to calculate cytokine concentration in the supernatants. Results are expressed as mean ± standard error of the mean (s.e.m.) of at least six independent experiments. Statistical significance

between treated and control cultures was analysed by Mann–Whitney U-test. P-values of P < 0·05 were considered find more statistically significant. To analyse the effect of virulence on the capacity of Leishmania parasites to enter and multiply within human DC we used two Lm clones differing by their virulence, which was established in BALB/c mice and two other Lm clones, HVΔlmpdi and LVΔlmpdi, generated from HV and LV, respectively, and invalidated for the lmpdi gene. We showed that HV promastigotes were internalized by DCs of all (n = 10) tested individuals with an infection rate (IR) and a parasite burden (PB) that increased significantly during the 3-day period (mean IR and mean PB ± s.e.m. were 42·3% ± 7·83 and 6·7 ± 0·99 at 24 h; 50·1% ± 7·64 and 12·4 ± 2·15 at 48 h; 66·3% ± 7·06 and 22·5 ± 7·29 at 72 h , respectively ) (Figs 1 and 2a,e). Interestingly, LV promastigotes failed to enter DCs from five

of 10 individuals (Fig. 1). In the other five donors, IR and PB were significantly lower than those observed in HV-infected DCs (5·9% ± 2·63 and 1·46 ± 0·6 at 24 h; 9·3% ± 4·43 and 2·9 ± 1·29 at 48 h; 11·7% ± 5·4 and 4·5 ± 2·27 at 72 h) Buspirone HCl (Fig. 2a,e). Differences observed in IR and PB between HV and LV were highly significant (P ≤ 0·0003 for IR and P ≤ 0·002 for PB during the 3-day culture). PB was significantly higher in HVΔlmpdi-infected DCs compared with LVΔlmpdi-infected DCs (P ≤ 0·01). For IR, a significant decrease was observed in LVΔlmpdi-infected DCs only at 72 h (P = 0·008) (Fig. 2b,f). Interestingly, IR and PB were lower in HVΔlmpdi-infected DCs when compared with HV-infected DCs. This result was significant for IR at 72 h (P = 0·03) and PB at 48 h and 72 h (P ≤ 0·01) (Fig. 2c,g).

In addition, association of Syk with FcRγ chain is also observed

In addition, association of Syk with FcRγ chain is also observed in the T cells of SLE patients and not in the normal population [10,41]. Syk-deficient eosinophils do not respond to FcγR activation, suggesting the requirement for FcR-mediated signalling for the Syk activation [42]. Syk is also essential for FcγR-mediated signalling in macrophages, neutrophils and monocytes [43,44]. Thus, T cell activation via Syk upon engagement of FcγRIIIA by ICs may be an important event for the development of autoimmune pathology. The results presented show that the formation of ICs and complement activation

may influence the T cell-mediated adaptive immune responses by the FcRγ–Syk-mediated signalling pathway. Syk also has the ability to act at several other levels in the TCR signalling cascade [31]. The presence of low-affinity FcRs that bind to ICs on CD4+ T cells is still considered CHIR-99021 order an open question [45]. We observed a subset of CD4+ T cells that demonstrated the presence of both FcγRIIIA and FcγRIIIB receptors. In these cells, IC treatment triggered the recruitment of FcRγ chain with membrane FcγRIIIA receptors and this resulted in phosphorylation of Syk, thus suggesting a role for FcRs in T cell signalling. The staining pattern of these receptors in human CD4+ T cells was similar to that of previously observed binding of aggregated mouse globulin to mouse T lymphocytes [46]. Both

the elevated levels of ICs and aberrant T cell activation are part of the autoimmune process. ICs are the only known see more ligands for low-affinity FcRs that contribute to lymphocyte signalling. Thus, defining a correlation among these two events is of significant importance for understanding the autoimmune pathology. Activation of Syk by ICs in T cells suggests a role for ICs in altered T cell phenotypes observed in autoimmunity. A contribution from

the FcRs in T cell activation has been suggested previously by a single report [47]. The CD3– Jurkat cells that have been transfected with the transmembrane region of the FcγRIII receptor show association with Lck (p56) and ZAP-70, the TCR signalling proteins. This suggests a link between FcRs and T cell signalling pathway proteins [48,49]. The phosphorylation of ζ-chain in the CD3 complex is the primary TCR signalling event, which triggers TCR activation upon peptide–major histocompatibility complex (MHC) engagement. Activation of TCR in the absence of CD3 suggests the presence of an alternate signalling pathway for T cell activation that may utilize low-affinity FcRs. We observed phosphorylation of both Lck and ZAP-70 in Jurkat cells treated with ICs and MAC in the absence of peptide–MHC engagement [26]. The CD8+FcγRIII+ T cells show proliferation in response to receptor cross-linking with ICs [36]. We also observed proliferation of naive CD4+ T cells in response to ICs in the presence of TCC [26].

“Please cite this paper as: Nunes, Krishnan, Gerard, Dale,

“Please cite this paper as: Nunes, Krishnan, Gerard, Dale, Maddie, Benton and Hoying (2010). Angiogenic Potential of Microvessel Fragments is Independent of the Tissue of Origin and

can be Influenced by the Cellular Composition of the Implants. Microcirculation17(7), 557–567. We have demonstrated that MFs isolated from adipose retain angiogenic potential in vitro and form a mature, perfused network when implanted. However, adipose-derived click here microvessels are rich in provascularizing cells that could uniquely drive neovascularization in adipose-derived MFs implants. Objective:  Investigate the ability of MFs from a different vascular bed to recapitulate adipose-derived microvessel angiogenesis and network formation and analyze adipose-derived vessel plasticity by assessing whether vessel function see more could be modulated by astrocyte-like cells. Methods:  MFs were isolated by limited collagenase digestion from rodent brain or adipose and assembled into 3D collagen gels in the presence or absence of GRPs. The resulting

neovasculatures that formed following implantation were assessed by measuring 3D vascularity and vessel permeability to small and large molecular tracers. Results:  Similar to adipose-derived MFs, brain-derived MFs can sprout and form a perfused neovascular network when implanted. Furthermore, when co-implanted in the constructs, GRPs caused adipose-derived vessels to express the brain endothelial marker glucose transporter-1 and to significantly reduce microvessel permeability. Conclusion:  Neovascularization involving isolated microvessel elements is independent of the tissue origin and degree of vessel specialization. In addition, adipose-derived vessels have the ability to respond to environmental signals and change vessel characteristics. “
“Please cite this paper as: Roustit and Cracowski (2012). Non-invasive Assessment of Skin Microvascular Function in Humans:

An Insight Into Methods. Microcirculation 19(1), 47–64. For more than two decades, Vitamin B12 methods for the non-invasive exploration of cutaneous microcirculation have been mainly based on optical microscopy and laser Doppler techniques. In this review, we discuss the advantages and drawbacks of these techniques. Although optical microscopy-derived techniques, such as nailfold videocapillaroscopy, have found clinical applications, they mainly provide morphological information about the microvessels. Laser Doppler techniques coupled with reactivity tests are widespread in the field of microvascular function research, but many technical issues need to be taken into account when performing these tests. Post-occlusive reactive hyperemia and local thermal hyperemia have been shown to be reliable tests, although their underlying mechanisms are not yet fully understood.

In contrast, in Mycobacterium leprae-infected humans, T cells usi

In contrast, in Mycobacterium leprae-infected humans, T cells using the Vβ6-, Vβ12-, Vβ14- and Vβ19-encoded TCRs are overrepresented in lesions when compared to blood (50). Similarly, Vβ3, Vβ6 and Vβ7 are dominant in the lesions of 50% of patients with Leishmania braziliensis infection

(50), and the Vβ14 and Vβ24 gene families are overrepresented in lesions caused by Wuchereria bancrofti (21). These differences may be because of the divergent access of blood supply Forskolin molecular weight to lesions and the liver. Indeed, in other diseases, parallels in the Vβ expression have been detected in sites of disease pathogenesis and peripheral blood. For example, there is selective expansion of TCR Vβ6 in tonsillar and peripheral blood T cells in patients with IgA nephropathy (51), and another study (52) demonstrated identical β cell-specific CD8+ T cell clonotypes in both peripheral blood and pancreatic islets of individual non-obese diabetic mice. The ability to detect CD8+

TEM cells in the blood of mice immunized with Pbγ-spz indicates that it will be highly relevant to assess in clinical trials the peripheral blood of human volunteers immunized with attenuated sporozoites. By analysing TCR Vβ expression in blood, we were able to follow the expansion of CD8+ TEM cells in Kinase Inhibitor Library chemical structure individual mice. The expansion pattern observed after immunization did not change with challenge and remained the same for 8 weeks thereafter. In a similar

fashion, Walker et al. (53) monitored the expression of Vα8 on Ag-selected CD8+Vβ10+ cells in response to an immune-dominant epitope expressed on P815-CW3-transfected cells. While there was substantial variation among responder mice in Vα8 usage, the repertoires of individual animals remained relatively stable over long periods of time (<1 year). Analysis of C57BL/6 mice infected with influenza virus demonstrated the persistence of CD8+Vβ7+ PA-specific T cells 200 days after infection (54). In recent years, there has been renewed interest in the use of a whole parasite vaccine strategy and there are now intense efforts under way to prepare and formulate attenuated either sporozoites that could be cryopreserved and then inoculated by syringe (55). This interest is fuelled mainly by the ability of the whole parasite to successfully induce long-term protection. Although the single recombinant protein vaccine, RTS,S, induces protective immunity in nonexposed adults and children residing in malaria endemic areas, the protection is short-lived, and CD8+ T cell responses are not detected (56). However, little is known about the nature, source and long-term maintenance of CD8+ T cell memory induced by attenuated parasite vaccination. It is likely that the induction and maintenance CD8+ T cell immune response generated to a whole parasite is different than that seen in response to a single protein, such as in a subunit vaccine.

In recent years T cell biology has been enriched and enlivened

In recent years T cell biology has been enriched and enlivened

by the description of two further subsets. Interleukin (IL)-17-producing T cells were identified as important drivers of autoimmune pathology, forcing the re-evaluation of the role of Th1 cells in models of autoimmunity [2–4]. Elucidation of the factors promoting development of these Th17 cells [transforming growth factor (TGF)-β, IL-6 and IL-21][5–8] and the regulators of their transcriptional profile (RORγt and RORα[9,10]) established Th17 cells as a third effector T cell subset (reviewed in [11]). The Selleck Vemurafenib three effector subsets appear to have evolved to cope with the threat posed by distinct classes of pathogen. Th1 cells are associated classically with intracellular bacteria and viral infections, Th2 responses are elicited by parasitic helminths, Palbociclib supplier while Th17 responses are protective against certain extracellular bacterial and fungal infections [11]. Dysregulated Th2 responses promote the development of allergy and asthma, while uncontrolled Th1 and Th17 responses can result in autoimmune inflammation; therefore, the actions of these effector CD4+ cells need to be controlled strictly. The

identification of a minor subpopulation of CD4+ cells capable of preventing the development of autoimmunity [12,13] revolutionized our concept of T cell regulation. Identification of forkhead box P3 (FoxP3) as the lineage-specific transcriptional PAK5 regulator determining this suppressive

phenotype [14,15] confirmed the status of FoxP3+ regulatory T cells (Tregs), as distinct from previously described effector subsets [16]. In the scurfy mouse, a frameshift mutation in FoxP3 results in production of non-functional product and a lethal lymphoproliferative disorder [17,18] caused by over-activation of CD4+ T cells [19]. Similarly, the human condition immune dysregulation, polyendocrinopathy, enteropathy, X-linked syndrome (IPEX) is caused by mutations of FoxP3 [20]. ‘Natural’ Treg (nTreg) provide the thymically derived FoxP3+ cells that prevent spontaneous inflammatory disease and provide the Treg population that are assessed in vitro when using naive mice [21]. In addition, T cell receptor (TCR) stimulation of naive T cells in the presence of TGF-β can drive de novo expression of FoxP3 in uncommitted naive T cells, providing a population of ‘induced’ Tregs (iTregs). Antigenic stimulation, therefore, can drive the polarization of naive T cells to become Th1, Th2, Th17 and/or iTreg cells, in addition to the activation of antigen-responsive nTregs. The balance of (and timing in the appearance of) these different populations is dependent upon the nature of the antigen presentation and the cytokine milieu.