While the levels of circulating CFH in subjects with altered glucose tolerance are usually increased [24], our study showed that the upregulation of CFH in T1D relatives was independent of their metabolic status. However, no evidence of association Raf kinase assay of CFH polymorphisms with T1D has been reported so far [25]. The other category of immune responses where differences observed on the level of a single gene upregulation

were also paralleled on the level of entire pathway represents cytokine and/or chemokine signalling. Namely, when DRLN was compared to the control group, we found the upregulation of genes encoding IL-21 receptor, IL-13 receptor (alpha1) and IL-28 receptor (alpha, IL-28RA). So far, the functional link to T1D and other T cell-mediated diseases was reported only for IL-21 [26, 27]. The analysis on a transcriptome level also revealed differences in the expression of proinflammatory IL-1 as well as of IL-7 and IL-15 cytokines. The recognition of Selleckchem HM781-36B IL-1 signalling as the highest-scored differentially activated pathway in DRLN versus DV comparison is an important outcome of this analysis. IL-1 signalling scored high even when the whole DRL group was compared to controls without consideration of the autoantibody status.

It is necessary to emphasize that none of the participants suffered from any apparent infection at the time of sampling. Several scientific reports described the relationship between IL-1 signalling and the type 1 as well as type 2 diabetes [28]. In this context, our finding suggests that enhanced proinflammatory activity in the group of relatives reflects an inherently increased basal level of signalling status rather than stimulus-mediated activation. The second highest-scored pathway in DRL (whole group) versus DV comparison was IL-7 signalling in B lymphocytes. Common genetic variants of IL-7 receptor alpha (IL-7RA) have been recently shown to affect susceptibility to multiple sclerosis and T1D. While the relationship between IL-7RA signalling and the regulation of T cell homeostasis is well established [29], the mechanistic link between IL-7 signalling in B lymphocytes and

development of T1D is still elusive. IL-15 signalling Non-specific serine/threonine protein kinase was recognized in DRL but not in DRLN versus controls comparison. This interleukin is crucial for NK-cell differentiation. Qin and co-workers observed reduced cell numbers and diminished responses of NK cells to IL-2 and IL-15 stimulation in children suffering from T1D [30–32]. It is of note that we have also identified differences in NKG2D signalling between DRL as well as DRLN and the control group. Changes in the activation of two chemokine cascades, CCR3 and CXCR4, were also revealed. CCR3 signalling in eosinophiles scored the highest in DRL versus patients with T1D. The protein encoded by CCR3 gene is highly expressed in eosinophils and basophils and is also detectable in Th1 and Th2 cells [33].

The significance of VSV-specific CD8+ T cells remaining sessile in clusters at (presumed) previous hot spots of infection is not obvious because VSV is not a chronic, persistent or latent viral infection. The author’s interpretation is that the T cells are not “smart” enough to know this, and are simply fulfilling a protective role against an infection that might recur at the same site. Gut-associated memory T cells are also out of equilibrium with the pool of recirculating memory cells 17. T cells that have been recently activated by antigen in gut draining lymphoid KPT-330 chemical structure organs such as mesenteric lymph nodes preferentially

acquire homing molecules that allow them to enter the lamina propria and intestinal epithelium 21. In addition, effector T cells activated in the spleen by viral or bacterial infection have the ability to traffic to any organ, including the gut 22. Thus, it seems that recently activated effector cells can enter these sites, but resting memory cells cannot. The lymphocytes in the gut-associated

lymphoid structures show an activated phenotype, including CD69 and granzyme expression and immediate effector function. The gut lumen contains a vast spectrum of microbial and food antigens which are usually ignored by the immune system. Nevertheless, the enormous surface area of the intestine and its exposure to ingested pathogens make it a key location for enhanced security. Despite the huge number of potential peptides in the gut derived from commensals and food, it is difficult to argue that all the resident

memory T cells in the gut epithelium and underlying structures Cobimetinib cell line meet antigen (or cross-reactive antigen) at this location. Rather it may be that their activated status provides an antigen nonspecific or innate function in maintaining the integrity of the intestine. Peripheral nonlymphoid organs and body surfaces, such as the skin and mucosa, contain the bulk of our lymphocytes. These are virtually all memory Tau-protein kinase cells and many score as effectors. Their role is to provide a rapid response to pathogen re-entry or reactivation; however, for these T cells on the front lines of our defenses, it still remains to be worked out what factors hold and maintain them at these locations. Conflict of interest: The author declares no financial or commercial conflict of interest. This article is editorially independent of Novartis. See accompanying reviews also written by winners of the 2010 Novartis Immunology Prizes, and the Forum article describing the Prizes http://dx.doi.org/10.1002/eji.201141436http://dx.doi.org/10.1002/eji.201141550http://dx.doi.org/10.1002/eji.201141682 “
“Regulatory T (Treg) cells are essential for maintaining self-tolerance and modulating inflammatory immune responses. Treg cells either develop within the thymus or are converted from CD4+ naive T (Tnaive) cells in the periphery.

Mouse splenocytes were stimulated with phorbol myristate acetate (PMA)/ionomycin

for 3–6 h and processed through the mouse IL-17 secretion assay detection kit. Cells were isolated by MiniMACS magnet and two consecutive MS columns and stained with CD154 antibodies (human only) and appropriate phenotyping Ibrutinib purchase markers. Cells cultured into lines (see Rauser et al. [9] for method) were also stained with HLA-restricted tetramers for various CMV pp65 peptides in addition to phenotyping antibodies. Flow cytometry was carried out using BD FACS Calibur and Miltenyi Biotec MACSQuant analysers. Human IL-17-producing cells were detected readily following 3 h Cytostim stimulation, typically forming 0·1% of viable T cells (Fig. 2a). The production of IL-17 was found only in CD154+ activated T cells, and confined almost exclusively to the CD4 subset (Fig. 2a). IL-17 was produced by 0·04–2% of human CD4 T cells (n = 21), thus there was a large amount of donor

variability. In accordance with previously reported in vitro-generated IL-17-producing selleck products T cells lines [10], IL-17-producing cells in PBMC were >90% positive for the C-type lectin-like receptor CD161 (Fig. 2b). Human IL-17-secreting cells could be isolated readily from Cytostim-stimulated PBMC and enriched to very high purities of more than 90% (Fig. 2a). Such isolated cells are excellent for determining the ‘natural’ delineation of immune responses, and cells co-processed with IL-17 and

IL-2 or IFN-γ secretion assays neatly illustrate the separation of Th1 and Th17 responses with mutually exclusive production of IFN-γ and IL-17 (Fig. 2c). Conversely, three populations of cells were seen when co-processed with IL-2 with a distinct IL-2+ IL-17+ population (Fig. 2c). In stark contrast to human cells, IL-17 was made by ifoxetine multiple different cell types in mouse spleen (BALB/c) – CD4+, CD8+, γ/δ TCR+ and natural killer (NK) T cells (Fig. 3a). IL-17 formed a major part of the cytokine responses of γ/δ and NK T cells at 18·8% and 6·4%, respectively. The peak levels of mouse IL-17 secretion were reached extremely quickly, with maximal numbers of IL-17 producing CD4+ T cells and maximum mean fluorescence intensity (MFI) of cytokine produced by 3–4 h (Fig. 3b). The kinetics of IL-17 production and amount of cytokine produced vary markedly from mouse strain to strain and this should be checked before embarking on a study. The housing conditions of the mice are also important; for example, specific pathogen-free (SPF) mice make no detectable IL-17 (data not shown). One of the few well-defined antigen-specific Th17 responses in humans is against C. albicans[11]. Although Candida-specific T cells are relatively rare – typically, <0·04% of CD4+ cells make IL-17 when stimulated with Candida lysate (Fig. 4) – it was possible to enrich these cells easily to >84% purity (Fig. 4).

, Viropharma and Cubist. “
“Extrathymically induced Foxp3+ regulatory T (Treg) cells contribute to the pool of Treg cells and are implicated in the maintenance of immune tolerance at Maraviroc price environmental interfaces. The impact of T-cell senescence on their generation and function is, however, poorly characterized. We report here that

steady-state induction of Foxp3 is impaired in aged T cells in vivo. In vitro assays further revealed that this defective generation of Treg cells was independent from the strength of TCR stimulation and arose before T-cell proliferation. Importantly, they also revealed that this impairment of Foxp3 induction is unrelated to known age-related T-cell defects, such as IL-2 secretion impairment, accumulation of activated T-cell populations, or narrowing of the T-cell repertoire. Finally, a loss of extrathymic induction of Foxp3 Staurosporine clinical trial and tolerance

to minor-mismatched skin graft were observed in aged mice treated by nondepleting anti-CD4 antibody. The T-cell intrinsic impairment of Treg-cell generation revealed here highlights age as a key factor to be considered in immune tolerance induction. Foxp3+ regulatory T (Treg) cells are required for the control of autoimmune responses and maintenance of immune homeostasis [1, 2]. Depending on their site of generation, two populations have been distinguished: tTreg cells generated in the thymus and pTreg induced in the periphery from mature conventional T (Tconv) cells. A key role of pTreg cells has been established in models of oral tolerance [3], colitis [4], transplantation

[5, 6], and in pregnancy [7, 8] in which pTreg cells allow the development of a suppressive T-cell repertoire adapted to evolving antigens encountered in the periphery. Aging is associated with altered immune responses to vaccination, infection, cancer, and dysregulation of inflammatory responses [9, 10]. In addition to a decrease in naïve T-cell numbers due to thymus involution [11, 12], functional impairment of T cells is a major component of the defective immune response in the elderly [13]. In particular, an early and transient IL-2 secretion defect in aged T cells leads to impaired proliferation and differentiation in fully functional Th1 and Th2 cells [14, 15]. We characteri-zed here the effect of T-cell senescence on pTreg-cell generation and report that T-cell intrinsic defects oppose the induction of Foxp3 in aged Tconv before cells both at the steady state and during induction of transplantation tolerance. To explore whether T-cell senescence affects pTreg production, we first compared in vivo Foxp3 induction at the steady state in Tconv populations isolated from either young (5–20 weeks) or old (60–65 weeks) Foxp3-eGFP mice. Highly purified CD4+eGFP− T cells (>99.99%) from young Foxp3-eGFP mice (Fig. 1A) were transferred into C57Bl/6 CD45.1+ congenic hosts, and 4 weeks after transfer, 0.4% of eGFP+ cells was detected in the donor T-cell population (Fig. 1B). In contrast, a 1.

Our experiments do not allow us to discern whether the reduced

anti-FVIII immune response is the result of the neutralization16 and/or elimination of the administered FVIII antigen by anti-FVIII IgG (as could be deduced from Fig. S1), or of the formation of immunomodulatory immune complexes between exogenous FVIII and the transferred maternal anti-FVIII IgG. However, our results are reminiscent of a previous report wherein immunization INK 128 molecular weight of low-density lipoprotein-receptor-deficient (LDLR−/−) female mice with OxLDL was shown to reduce the development of atherosclerotic lesions in susceptible LDLR−/− offspring;17 the protective effect in progeny was attributed to IgG–LDL immune complexes. In the present study, protection from the development of FVIII inhibitors was conferred by the maternal transfer of anti-FVIII IgG1 antibodies and by the reconstitution of naive mice with pooled anti-FVIII IgG, containing > 80% IgG1.18

Interestingly, the presence of anti-FVIII IgG1 antibodies has been associated with success of tolerization against FVIII in patients with congenital and acquired haemophilia A.19 The presence of immune complexes between FVIII and FVIII inhibitors (of the IgG4 subclass) has been documented in an inhibitor-positive patient with acquired haemophilia.20 Whether immune complexes between the transferred anti-FVIII IgG1 and the administered find more FVIII are present in the FVIII-deficient mice remains to be determined. Of note, IgG1, both of human and mouse origins, has a higher affinity for the inhibitory receptor FcγRIIB than other IgG

subclasses.21,22 It is possible that cross-linking of FVIII-specific B-cell receptors and FcγRIIB on B lymphocytes by immune complexes containing FVIII and anti-FVIII IgG1, leads to anergy or deletion of naive B cells at the time of priming, so transiently protecting the animals from the development of FVIII inhibitors in our model. Such a mechanism could also account for the deletion of FVIII-specific B cells reported in a haemophilic mouse model of immune learn more tolerance induction.23 Alternatively, immune complexes have also been shown to interfere with the activation of dendritic cells upon interaction with FcγRIIB, preventing proper T-cell priming.15 Such a mechanism could account for the decreased FVIII-specific T-cell response, which is demonstrated in our work. We wish to thank Professor David W Scott (University of Maryland, Baltimore, MD) for his critical reading of our manuscript. This work was supported by INSERM, CNRS, Agence Nationale de la Recherche (ANR-07- JCJC-0100-01, ANR-07-RIB-002-02, ANR-07-MRAR-028-01). Human recombinant FVIII was provided by CSL-Behring (Marburg, Germany). Y.M. and M.T. are recipients of fellowships from Fondation pour la Recherche Médicale and from Ministère de la Recherche (Paris, France), respectively. The authors reported no potential conflicts of interest. Figure S1.

The increase in larvae from day 3 to 7 days post-challenge was probably due to the gradual migration of L3 from the stomach to the different sections of the small intestine (24,25). Individuals never completely cleared the infection, and nematodes were still present, although with very low numbers, in the first section at 120 days post-challenge. Graphidium strigosum: Abundance was consistently higher in the fundus compared to the antrum, and no temporal changes were PD0332991 supplier observed between sampling points (or the interaction between sampling point and

organ section), when differences among individuals and the nonindependent sampling of the two parts of the stomach from the same individual were considered (Figure 1b, Table 2). All infected individuals maintained a constant number of nematodes up to 120 days post-infection. The drop in parasite number Selleck Mitomycin C in the antrum at day 40 and 60 post-challenge was caused by a sampling procedure and should not be considered biologically relevant. These

results were consistent with our long-term observations on the intensity of infection of these nematodes in free-living rabbits of different age, specifically, rabbits can reduce or clear T. retortaeformis but not G. strigosum. Trichostrongylus retortaeformis: A strong IFN-γ expression in the first section of the small intestine of infected rabbits was observed during the first 30 days post-challenge; thereafter, no dominant pattern was observed (Figure 2a). Analysis based on the normalized Ct values (that differs from the 2−ΔΔCt transformation in Figure 2) found that changes in IFN-γ and IL-4 significantly Teicoplanin differed between treatments (infected and controls) and time post-infection (DPI): IFN-γ decreased while IL-4 increased in transcription with the infection course, IL-10 exhibited constant expression over time although was significantly higher in infected compared to controls (Table 3). Graphidium strigosum: A robust IL-4 expression was observed in the top section of

the stomach of infected rabbits; however, the between-individual variability was high as highlighted by the large standard error bars (Figure 2b). Based on the Ct values, the expression of the three cytokines was higher in the infected compared to the controls but no significant changes were recorded during the course of the infection (Table 3). The two infections clearly showed different cytokine profiles, which imply differences in the effectors and timing of their activation as well as their dynamical consequences. The somatic antibody response of infected rabbits to L3 and adult stage was similar both for IgA and IgG against the two nematodes supporting the hypothesis that the two parasite stages cross-react at the antibody level. As such, we only present the results for the adult stage (Figures 3 and 4) and summarize in the supplement the findings for the L3 stage (Figures S1 and S2).

(Mouse AV14 and human AV24 correspond to TRAV11 in the WHO/IMGT nomenclature.) This rearrangement is further characterized by a VJ gene segment transition of uniform length, which contains a germ line-encoded amino acid at position 93 (glycine in mice and serine in humans) in most instances [3, 4]. The CDR3s of the β-chain are highly variable but the BV (Vβ) gene segments used are mainly BV8S2,

BV7, and BV2 in mouse and BV11 in human (homologue to mouse BV8S2) [1]. Most but not all iNKT cells express NKR-P1C (also known as NK1.1) in mice and NKR-P1A (CD161) in humans. Nonetheless in humans, only a minor fraction of all NKR-P1A+ αβ T cells are iNKT cells [1, 5]. Mouse iNKT cells are CD4+ or CD4 and CD8 double negative (DN) whereas human iNKT cells are DN, CD4+, and CD8α+ [5, 6]. iNKT cells home to particular tissues this website GDC-0973 supplier such as the liver, constituting up to 30% of all intrahepatic lymphocytes (IHLs) in certain mouse-inbred strains such as C57BL/6 [1]. In humans however, the frequencies are much more reduced (about 0.5% of all CD3+ cells in the liver) and vary considerably between individuals [1, 7]. In contrast to most αβ T cells, which recognize peptides presented by MHC molecules, the semi-invariant TCR of iNKT cells is specific for lipid antigens presented by CD1d, a nonpolymorphic MHC class

I-like molecule [1]. The first and still one of the strongest antigens Amino acid identified is KRN7000 (commonly referred to as α-Galactosylceramide (α-GalCer)), which is a synthetic derivate of a compound isolated from the marine sponge Agelas mauritanus [1]. Importantly, iNKT cells can be unequivocally identified using α-GalCer-loaded CD1d oligomers, distinguishing them for example from non-iNKT T cells, which express NKR-P1 [5]. iNKT cells rapidly secrete large amounts of many different cytokines after activation and a significant fraction of them even simultaneously produces the Th1 and Th2 signature cytokines IFN-γ

and IL-4 [1]. Largely due to the effects of their secreted cytokines on other cells, iNKT cells greatly influence the immune system. Studies in mice and clinical observations in humans have shown iNKT cells to suppress or promote autoimmunity as well as responses against infections and tumors, making iNKT cells a promising target for immunotherapy. Nevertheless, there is still much to be learned about how iNKT-cell stimulation results in such different outcomes. Genetic as well as functional studies have indicated the existence of iNKT cells in the rat but the direct identification of these cells has thus far been lacking. Rats have one CD1d, two BV8S2 (BV8S2 and BV8S4), various AV14, and one AJ18 homologues and the typical AV14AJ18 rearrangements [8-10]. The presence of an AV14 gene family with up to ten highly similar members is a particularity of rats not found in humans or mice [9, 11, 12].

Detection of cleaved caspase 3 through Western blot analysis confirmed chronic shear stress-mediated protection from TNF-α. In the presence of the nitric oxide synthase inhibitor, LNMA (Nω-monomethyl-l-arginine), chronic protection remained. Treatment with a de novo protein synthesis inhibitor, cycloheximide, eliminated this protective effect. Isotopic-labeling experiments, coupled with LC–MS/MS (liquid chromatography–tandem mass spectrometry) of isolated components of the TNF-α pathway revealed that CARD9, a known activator of the NF-κB pathway, was increased (60%) in sheared cells versus nonsheared cells. This

result was confirmed through Western blot analysis. Our data suggest that de novo formation of proteins is required Ixazomib datasheet for protection from TNF-α in ECs chronically exposed to shear stress, GSI-IX ic50 and that CARD9 is a candidate protein in this response. “
“Please cite this paper as: Maejima, Kawai, Ajima and Ohhashi (2011). Platelet-Derived Growth Factor (PDGF)-BB Produces

NO-Mediated Relaxation and PDGF Receptor β-Dependent Tonic Contraction in Murine Iliac Lymph Vessels. Microcirculation 18(6), 474–486. We studied the effects of PDGF-BB on changes in the diameters of murine lymph vessels with or without intact endothelium. PDGF-BB induced dilation of the lymph vessels with endothelium. Pretreatment with l-NAME or removal of the endothelium caused a significant attenuation in the PDGF-BB-induced dilation. PDGF-BB also produced dose-related reduction of the eltoprazine diameters of the lymph vessels without endothelium. To evaluate intracellular signal transduction and Ca2+-dependence of the PDGF-BB-induced tonic contraction, we investigated the effects of imatinib, GW5074 (an

inhibitor of Raf-1 kinase), U-73122 (an inhibitor of phospholipase C), and xestospongin C on the PDGF-BB-induced reduction responses. All of these inhibitors caused a significant attenuation in the PDGF-BB-induced reduction response that was significantly decreased by treatment with Ca2+-free Krebs-bicarbonate solution or nifedipine. Higher concentrations of PDGF-BB produced a marked reduction of lymph vessel diameter within both high K+ Krebs-bicarbonate solution and Ca2+-free high K+ Krebs solution containing 1 mM EGTA. These findings suggest that PDGF-BB induced endothelium-dependent NO-mediated relaxation of lymphatic smooth muscles in murine lymph vessels. PDGF receptor β-mediated tonic contraction of the muscles through increased Ca2+ influx through the membrane and the release of membrane-bound and intracellular Ca2+. “
“Extracellular Ub is an immune modulator that plays a role in suppression of inflammation, organ injury, myocyte apoptosis, and fibrosis. The purpose of this study was to investigate the effects of extracellular Ub on the process of cardiac angiogenesis.

23 Similarly, pregnancy impairs resistance to Salmonella leading to rapid, fatal infection.24 As stated by Loke and Moffet in their review in Nature Immunology,25‘ruminations about the immune system during pregnancy are mostly centred on the acquisition of maternal tolerance to the allogeneic foetus’. This

view is probably too simplistic. Failure to distinguish between the local and systemic immune response has led to a great deal of confusion. Another problem is dealing with pregnancy as if it had first to cope with the adaptive immune system. But placentation appeared in the Devonian,26 in an era where T cells did not exist, and evolution had barely produced IgM. But NK cells did already exist. Such an immune system still exists nowadays in some sharks. The Selleck Dabrafenib adaptive immune system later adapted to pregnancy, which then used it for immunotrophism27 and local vessel remodelling, selecting a specialised unique population, uterine NK cells. After Medawar’s reflections, his collaborator Billingham started experiments28 with Alan Beer and Judith Head. What they found was that the mother is not Apoptosis inhibitor systemically, or even locally, tolerant to paternal alloantigens. Let us recall that an animal A, made tolerant to B, accepts any B tissue. Tolerance

is incomplete or absent if some tissues are accepted but others more immunogenic are rejected. Thus, the classical

challenge is skin allografts, not weakly immunogenic tumours as painstakingly defined by Brent, Billingham, and Medawar28 at ‘the birth of transplantation Nintedanib (BIBF 1120) biology’.29,30 The results of Beer and Billingham’s skin graft studies in a first pregnancy are so easily reproducible, even with strongly immunogenic tumours,31–33 that it is surprising they are so often ignored: (1) in first pregnancy, synpregnant or allopregnant mice do reject HY (male) syngeneic skin grafts exactly as virgins. MHC identical, minor loci different grafts are also rejected as in virgin hosts; (2) MHC alloskingrafts have a similar fate, albeit with rejection kinetics of, at best, 2 days, which is attributed to gestational corticoids; (3) not least, intrauterine grafts at a minimal distance from the implantation site will enjoy only slightly prolonged survival, unless placed in the decidua basalis itself, or in pseudo pregnant decidua, where these sites behave then as immunologically privileged; (4) finally, Woodruff34 showed that foetal tissues grafted in the leg will be rejected during pregnancy. In a tolerant animal, a new, e.g. post-induction of tolerance, challenge by immunisation will not induce rejection of any matched tissue. Indeed, Mitchison, and later on Lanman, showed a ‘lack of harm to foetus from sensitisation of the mother’.

5a). In addition, the percentage and total number of switched GC B cells were also enhanced after late stage Treg-cell disruption. These data indicate that Treg cells participate in the control of GCs throughout the entire response, and not just at the induction phase. Given the observation that Treg cells participate in the control of GC reactions, it was of interest to explore the frequency and phenotype of the splenic Treg-cell population after immunization with SRBC. To monitor Treg cells, Foxp3-GFP reporter mice were used.47 As shown in Fig. 6(a), CD4+ Foxp3+ T cells are readily detected in the spleens of these mice, allowing for enumeration and phenotypic

characterization. Of interest, the proportion of Foxp3+ Treg cells within the splenic CD4+ compartment was unaltered throughout the GC response Ibrutinib manufacturer (Fig. 6b), although total cellularity of the spleen increased modestly at days 8 and 12 (data not shown). As iTreg cells are probably activated to control the humoral find more response to novel antigens,

a range of surface markers were examined in an attempt to identify an activated iTreg-cell sub-set. When comparing naive with SRBC-challenged mice, no differences were found in the proportion of Treg cells expressing CD103, CD45RB, CD62L, CD178, GITR or PD-1 at any time-point (data not shown). Several reports have demonstrated the presence of Treg cells within the GCs of human and mouse secondary lymphoid tissue,44,45,60,61 indicating their ability to migrate into activated follicles.62 Accordingly, CXCR5 and CCR7 expression was examined on CD4+ Foxp3+ T cells from naive and immunized mice. As shown in Fig. 6(a), the splenic Treg-cell population consists of four sub-sets defined as CXCR5− CCR7+, CXCR5lo CCR7lo, CXCR5 CCR7− and CXCR5+ CCR7−. CXCR5− CCR7+ Treg cells would be expected to reside in T-cell zones with CXCR5lo CCR7lo Treg cells positioned at the borders of T-cell : B-cell

areas. CXCR5− CCR7− Treg cells would probably be found in red pulp tissue. Importantly, CXCR5+ CCR7− Treg cells should have the ability to migrate into B-cell follicles with the potential to control B-cell activity locally. In naive mice (day 0), the CXCR5− CCR7+, CXCR5lo CCR7lo, CXCR5− CCR7− and CXCR5+ CCR7− sub-sets composed 29%, 14%, 30% BCKDHB and 27% of the Treg-cell compartment, respectively. It is of interest that all four sub-sets exist in unimmunized mice, suggesting that Treg cells patrol all areas of the spleen under steady-state conditions. The four Treg-cell sub-sets were similarly enumerated in SRBC-immunized mice at days 8, 12 and 18 post-challenge. Figure 6(c) shows no change in the frequency of CXCR5− CCR7+ and CXCR5+ CCR7− Treg cells during the course of the response, indicating no major shift of Treg cells from the T-cell zone into activated follicles. Percentages of CXCR5lo CCR7lo and CXCR5− CCR7− Treg cells were also unchanged (data not shown).