Splenocytes were cultured in anti-CD3 coated flat-bottom 96-well plates (0.5 × 106 cells/well) in the presence of increasing concentrations (0–1000 ng/mL) of the immunosuppressive drug MP [15]. For MOG35-55 stimulation, splenocytes were harvested from EAE mice, cultured at 0.5 × 106 cells/well in a U-shape 96-well plates and stimulated with 10 μg/mL MOG35-55. Culture plates were incubated at 37°C in a 5% CO2 atmosphere. After 48 h incubation, supernatants were harvested and stored at −80°C until cytokine analysis. Levels

of IL-2, IFN-γ, IL-4, IL-6, IL-10, IL-1, TNF-α, MCP1, and IL-17A were measured either with a multiplex ELISA kit (Quansys Biosciences, Logan, Utah) or with individual cytokine sandwich ELISA kits (Biolegend, San Diego, CA) as indicated in figure legends and according to manufacturer’s instructions. The immunosuppressive effect of MP is presented as percent of cytokine production without NVP-AUY922 nmr MP. Mice were immunized by subcutaneous injection

into flanks of 100 μg MOG35-55 emulsified in CFA (Difco, Detroit, MI). Pertussis toxin (List Biological Laboratories, Campbell, CA) was injected intraperitoneally (500 ng/mouse) selleck immediately following MOG35-55 injection and again 48 hours later. From day 9 postimmunization, mice were examined daily for clinical signs of the disease and the manifestation of the disease was graded on a 0–5 scale according to the following parameters: 0 = no clinical signs; 0.5 = loss of tail tonus; 1 = tail paralysis; 2 = partial hind-limb paralysis; 3 = hind-limb paralysis; 4 = complete paralysis; 5 = death. All statistical analyses were performed with

GraphPad Prism version 5.02 for Windows (GraphPad Software, San Diego, CA). All variables are expressed as mean ± SEM. p-values were calculated with Student’s t-test or ANOVA test as indicated in figure legends. We thank Dr. Tali Brunner and Prof. Marta Weinstock-Rosin for their valuable comments. We thank Dr. Irit Solodkin for graphical editing the manuscript figures. The Israel Science Foundation and Israel Ministry of Health supported this study. The authors declare no financial or commercial conflict of interest. As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re-organized TCL for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. Fig. 1. CVS induces anxiety-like behaviors. Anxiety levels were quantified following 24 days of CVS or nonstress conditions. The elevated plus maze (A–B) and open field tests (C) were performed as described in Materials and methods. Bar graphs represent means ± SEM of 20–21 mice in each group, pooled from three independent experiments. p-values were calculated by Student’s t-test. **p < 0.01; ***p < 0.001.

We conclude that modification of antigen with either 3-sulfo-LewisA or tri-GlcNAc enhances cross-presentation and permits Th1 skewing, through specific targeting of the MR, which may be beneficial for DC-based vaccination strategies to treat cancer. Activation of antigen-specific cytotoxic T cells is crucial for the induction of adequate

anti-tumor immunity. Since most tumor cells are poorly immunogenic, optimal presentation BVD-523 order of tumor-derived antigens in MHC class I molecules on the surface of antigen presenting cells is required. An important mechanism that allows DCs to present exogenous antigens, such as tumor-derived antigens, in MHC class I molecules is cross-presentation 1. At tumor lesions, multiple factors and cells are present that prevent the proper activation of DCs that enter the lesion to sample for antigens 2, 3. Consequently, these DCs will not be able to properly activate antigen-specific CD8+ T cells in the tumor-draining LN. To obtain therapeutic anti-tumor immunity powerful vaccination protocols are required. Current strategies focus

either on ex vivo loading of autologous DCs as well as specifically targeting of antigens to DCs in vivo. These new therapies may be combined with a Treg depletion regimen, as these cells have been shown to block anti-tumor immune responses 3–6. As a classical C-type lectin Pritelivir receptor (CLR), the mannose receptor (MR) binds carbohydrate structures such as mannose, fucose and N-acetylglucosamine (GlcNAc) in a calcium-dependent manner 7, 8. Besides these carbohydrate structures, the MR has recently also been reported to bind sulfated sugars, such as sulfated oligosaccharides of the blood group antigens LewisA (LeA) and LewisX (LeX) 8–10. Binding of these types of ligands occurs via the cysteine-rich (CR) region of the MR and in a calcium-independent manner 8. The MR has been proposed to mediate antigen uptake and presentation by DCs based on the finding that mannosylated proteins are presented (-)-p-Bromotetramisole Oxalate more efficiently than non-mannosylated proteins 11, 12. Fusion of an MR-specific monoclonal antibody to tumor antigens enhanced MHC class I-restricted T-cell

responses 13. Additionally, the glycoprotein ovalbumin (OVA), which contains mannose residues, was reported to be endocytosed through the MR, upon which the antigen was transferred to early endosomes, resulting in strong cross-presentation 14, 15. By contrast MR-mediated uptake of OVA did not induce CD4+T-cell responses. Processing of native glycosylated OVA in the early endosomes occurs in a TAP-dependent manner. Transport of TAP from ER to the endosomes is mostly, but not entirely, dependent on toll-like receptor-4 (TLR4)/MyD88 signaling 15. Although these studies report that the MR is an endocytic receptor for mannosylated OVA, in the human setting mannose may simultaneously target other CLR such as DC-SIGN, which shares specificity for mannose 16.

Although a variety of cytokines were produced by 7/16-5 CD4+ T cells after in vitro culture with both HBcAg and p120–140 peptide presented by either B cells or dendritic cell (DC)/macrophage (MΦ) APCs, no significant production of cytokines was detected in the culture of HBeAg-specific DN T cells. Because HBeAg-specific DN T cells predominate in ABT-263 datasheet a 4-day culture and are only observed in HBeAg-expressing dbl-Tg mice, we examined the possibility that the DN T cells possessed regulatory activity. In previous unpublished experiments, total spleen

cells from 7/16-5 × HBeAg dbl-Tg mice inhibited the HBeAg-specific production of cytokines by 7/16-5 effector cells, whereas, fractionated CD4+, CD8+ or both did not inhibit the activation of effector cells. Therefore, we fractionated the DN T cells from 4-day HBeAg-specific cultures and co-cultured the DN, Vβ11+ T cells with 7/16-5 effector T cells in the presence of p120–140 and measured antigen-specific expansion and cytokine (i.e. IL-2 and IFN-γ) production by the 7/16-5 T cells. As shown in Fig. 5(a), the cytokine production of the 7/16-5 effector T cells was dramatically

suppressed Selleck Autophagy inhibitor by the DN T cells, and the proliferation of the CD4+, Vβ11+ effector T cells was also inhibited even at an effector cell : Treg cell ratio as low as 32 : 1. This is a very low ratio of Treg cells to effector cells and indicates potent regulatory activity by the DN T cells. Further studies will be needed to clarify the precise mechanism of suppression. These data indicate that the DN T cells are HBeAg-specific, highly proliferative and effective suppressors, which defines a unique population of HBeAg-induced Treg cells in 7/16-5 × HBeAg dbl-Tg mice. To investigate whether this suppression by DN T cells is only specific for the 7/16-5 Tg-TCR, we investigated the inhibitory effect of DN T cells on a polyclonal HBeAg-specific T-cell population. We immunized B10 mice with 20 μg HBeAg to prime polyclonal

HBeAg-specific T cells, and harvested spleen cells after 10 days and restimulated the spleen RG7420 order cells in the presence of HBeAg and the indicated numbers of DN T cells. As shown in Fig. 5(b), even at a 10 : 1 effector : DN T-cell ratio, IL-2 production was effectively suppressed indicating that the Treg cell activity is functional for a polyclonal HBeAg-specific CD4+ T-cell response, and is not restricted to 7/16-5 Tg-TCR-bearing effector cells. Furthermore, to confirm whether this inhibitory effect is HBeAg specific or not, we investigated the inhibitory effect of DN T cells on cytokine production in an unrelated MHC class II-restricted TCR-Tg lineage, OT-II (Fig. 5c). The DN T cells activated in vitro inhibited the production of IL-2 from OT-II effector cells at a ratio of 8 : 1 (effector cell : regulatory cell) at day 2. Similar inhibitory effects were observed in IFN-γ production at day 4.

The tissue expression profile of TSGA10 mRNA throughout various organs was studied by quantitative PCR performed on cDNA from human tissue. Primers were designed with Beacon Designer® version 5.11 software (Premier Biosoft, Palo Alto, CA, USA) with one primer flanking an intron–exon junction to avoid amplification of genomic DNA. Quantitative PCR was carried out on human normalized multiple-tissue cDNA panels (BD Bio Sciences, Palo Alto, CA, USA) as well as pituitary, aorta (Stratagene

Cloning Systems) and adrenal cortex cDNA prepared from normal adrenal tissue removed during adrenal adenoma surgery. Reactions were performed on a MyiQ iCycler (Bio-Rad, Hercules, CA, USA) in a volume of 25 μl, with 200 nm of each primer using iQ™ SYBR®Green Selleckchem MG132 supermix (Bio-Rad) as per the manufacturer’s instructions. All samples were run in triplicate. Thermal cycles consisted of an initial denaturation step of 95 °C for 3 min, followed by 40 cycles of 95 °C for 15 s, 60 °C for 30 s and 72 °C for 30 s. Standard curves were then established from the serial dilution of TSGA10 and control glyceraldehyde-3-phosphate

dehydrogenase (GAPDH) PCR templates. TSGA10 mRNA levels were deduced from the standard curve and normalized to the endogenous GAPDH tissue content. A total of 27 cDNA clones were isolated and identified from immunoscreening of a human pituitary cDNA expression library with the sera from two APS1 patients, one with clinical GH deficiency and one with no reported pituitary manifestations. These clones represented 11 different proteins of AZD1208 ic50 which one was TPH isoform 1, a well-known APS1 autoantigen [19]. Recombinant proteins Chlormezanone from the remaining 10 cDNA clones were produced by ITT and immunoprecipitation was performed against a test panel of sera from six APS1 patients and five healthy blood donors to determine the possible antigenicity. Most of these recombinant products were recognized solely by the screening serum, by both APS1 sera and control sera or by none of the sera. A single clone TDRD6, isolated from the patient with pituitary manifestation was further analysed

and found in 49% of APS1 patients as reported previously [15]. An additional cDNA clone isolated from the patient without any pituitary deficits encoded testis specific, 10 (TSGA10), a gene located on chromosome 2q11.2. ITT of two of the TSGA10 clones resulted in good quantities of recombinant proteins that were used for immunoprecipitation with the test panel of sera. Both TSGA10 recombinant proteins were efficiently immunoprecipitated by the screening serum but not by any of the healthy controls; one of the corresponding TSGA10 clones was therefore selected for further studies. The TSGA10 gene consists of 19 exons spanning over 80 kb of genomic DNA. Two transcript variants have been reported, differing in the 5′ UTR. Both variants are transcribed from exon 6 to exon 21 and encode a 698 amino acid protein.

R. K. is a recipient of CCFF doctoral award. The authors thank Dr. Michel C. Nussenzweig (Rockefeller University) for reading the article. Conflict of interest: The authors declare no financial or commercial conflict of interest. “
“Vitamin D3 (VD3) is a steroid hormone that regulates bone health and numerous aspects of immune function and may play a role in respiratory health. We hypothesized that T helper type 2 (Th2) disorders, chronic rhinosinusitis with nasal polyps (CRSwNP) and allergic fungal rhinosinusitis (AFRS) would have VD3 deficiencies, resulting in increased mature dendritic

Roxadustat datasheet cells (DCs) and bone erosion. We conducted a retrospective study examining VD3 levels in patients with AFRS (n = 14), CRSwNP (n = 9), chronic rhinosinusitis without nasal polyps (CRSsNP) (n = 20) and cerebrospinal fluid leak repair (non-diseased controls) (n = 14) at time of surgery. Circulating immune cell levels were determined by immunostaining and flow cytometric analysis. Plasma VD3 and immune regulatory factors (granulocyte–macrophage colony-stimulating factor and prostaglandin E2) were measured by enzyme-linked immunosorbent assay. It was observed that CRSwNP and AFRS demonstrated increased

circulating DCs, while chronic rhinosinusitis without nasal polyps displayed increased circulating macrophages. CRSwNP and AFRS were to found this website to have insufficient levels of VD3 which correlated Immune system inversely with circulating numbers of mature DCs, DC regulatory factors and bone erosion. CRSsNP

displayed no change in circulating DC numbers or VD3 status compared to control, but did display increased numbers of circulating macrophages that was independent of VD3 status. Lastly, VD3 deficiency was associated with more severe bone erosion. Taken together, these results suggest support a role for VD3 as a key player in the immunopathology of CRSwNP and AFRS. While the exact cause of the persistent symptomatic inflammation associated with chronic rhinosinusitis (CRS) is unknown, it is thought to be the result of numerous interactions between environmental factors and the host immune system. CRS can be subdivided into two categories: CRS without nasal polyps (CRSsNP), which displays elevated levels of T helper type 1 (Th1) and Th2 cytokines, and CRS with nasal polyps (CRSwNP) which is heavily Th2 skewed [1]. Elevated levels of Th2 cytokines contribute to the symptoms of CRS by stimulating mucus production and recruitment of eosinophils [2]. Dispersed throughout the nasal and sinus mucosa are antigen-presenting cells (APC), among which are dendritic cells (DCs) and macrophages, that play a critical role in regulating Th1/Th2 skewing.

Monocytes expressing an anti-inflammatory phenotype have been observed

in vivo [11, 20]. Whether GA induces anti-inflammatory DAPT in vitro monocyte phenotypes directly or via modulation of other cell types has been unclear. Previous reports show that stimulation of anti-inflammatory/regulatory T cells by GA-modulated APC depends on MHC class II–restricted antigen presentation. However, MHC class II is not required to facilitate GA-dependent anti-inflammatory monocyte functions, suggesting that induction of anti-inflammatory monocyte function by GA does not require T cells [11]. Our data show that GA is able to further reduce proliferation of self-reactive T cells by directly enhancing T cell suppression by monocytes. Monocyte-like cells with the ability to suppress immune responses have been described in a variety of experimental models including tumours [31], allograft rejection [32], experimental autoimmune myocarditis [33] and EAE [34]. Furthermore, freshly isolated naïve blood monocytes [15] as well as monocytes generated in culture

from naïve bone marrow [33] exhibit the ability to suppress in vitro T cell proliferation. Here, we show that GA directly modulates monocytes in vivo in an MHC class II–independent manner, resulting in enhanced T cell suppressive function. Importantly, this suppressive ability does not depend on the presence of antigen in the culture, thus expanding on the findings of Weber et al. [11] concerning the role of monocytes in counteracting autoimmunity during GA treatment. Autoimmunity is associated with a Histamine H2 receptor break in tolerance resulting in the inappropriate expansion of self-reactive HDAC inhibitor T cells. It has recently been shown that loss of constitutive monocyte-dependent suppression of autoreactive T cell activation may be a contributing factor in the development of EAE in mice [20]. Interestingly, a reduction in T cell proliferation has been suggested to be part of the mechanism by which GA ameliorates MS. In the light of

current and earlier findings [11], it appears that GA treatment plays a key role in re-establishing type II suppressor function as well as the ability to directly suppress T cell proliferation by monocytes and thereby recover the tolerance to self-antigens. Previous in vitro studies have provided evidence of direct binding of GA to MHC class II [35], although the functional relevance of this binding is controversial. Our data show that MHC class II is not required for either GA binding or enhanced suppressor function of blood monocytes in vivo following intravenous GA administration. The fast rate of binding of GA to the blood monocytes indicates that GA uptake is likely to be cell surface receptor mediated rather than via less specific mechanisms such as macropinocytosis. Although GA binding to αMβ2 integrin on human monocytes has been reported in vitro [36], in this study, we only observed binding of GA to blood monocytes in vivo.

In all likelihood, the ~14-kDa region may have other protein fragment(s) that went unnoticed with Coomassie Blue staining of the gel. This assumption is supported by results of Western blot of fractionated ES–H.c-C3BP with the antiserum raised against the ~14-kDa band where an additional band of ~20 kDa was also stained by the antibody. In some blots, a faint band in the 37-kDa region was also seen, but it faded after membrane drying. The monomeric form of GAPDH can associate to form multimers [22]. Thus, the cross-reacting high molecular bands observed in the Western blot of adult parasite extract with anti-H.c-C3BP antiserum may be multimers of GAPDH,

which degraded on storage to lower-size polypeptides. The susceptibility

of GAPDH to hydrolysis is further supported by selleck its degradation during storage with the generation of multiple fragments including the ~14-kDa band. The hydrolysis of GAPDH in the ES products may be facilitated by the parasite proteases that are secreted [23]. Proteome analysis of H. contortus ES products suggested presence of five glycolytic enzymes [21]; GAPDH may be one of these. The fact that the antibodies against GAPDH were present in the sera of the infected animals suggests that the enzyme was secreted by the parasite and recognized BEZ235 order by the host immune effector cells. The strong evidences suggesting 14-kDa H.c-C3BP as GAPDH representative were further supported by other facts. The recombinant H. contortus GAPDH also bound to C3 protein and inhibited complement-mediated lysis of sensitized erythrocytes. Also, the presence of parasite GAPDH inhibited MAC formation. Pathogens have devised different ways to evade the host immune system. Innate

immune system is the first line of defence against the pathogens including parasites. This system exerts significant evolutionary pressure on pathogens, which have developed protective mechanisms [24-26]. Complement system, which includes a series of proteins, is an arm of the innate defence system. In recent Anidulafungin (LY303366) years, multiple complement evasion strategies have been identified in pathogens. Staphylococcus aureus, a Gram-negative bacteria, that infects human and animals has multiple complement-inhibitory proteins. This bacterium secretes a complement-inhibitory protein (SCIN) that affects C3 convertase function [27]. Two other complement-modulatory proteins of S. aureus are as follows: extracellular fibrinogen-binding protein (Efb) that binds to C3 and inhibits complement activation and EhpA, a homologue of Efb, with a size of ~10 kDa is also secreted by S. aureus and inhibits alternate complement pathway by altering the complement C3 conformation [28]. Streptococci have a surface protein that is also secreted; this protein binds to complement C5a. C5a is known to activate neutrophils which release H2O2 that is lethal.

On day −1, mice were injected i.p with 0.5×106 BM-derived DC, were pulsed with either 10 μg/mL of TCR peptide B5 (group one) or the control B1 peptide (group two). A third group

of mice were injected with PBS only. On day 0, mice were challenged with MPBAc1-9/CFA/PTx and EAE was monitored. Injection of DC pulsed with peptide B5 was associated with significant protection from EAE compared with mice injected with B1-pulsed DC or PBS only (Fig. 5). The disease scores of mice treated with B5-pulsed selleck products DC were significantly lower (p<0.0001) than mice treated with B1-pulsed DC. Collectively, these data demonstrate that DC loaded with TCR peptide B5 activate CD4+ Treg, resulting in protection against MBP-induced EAE disease. It has been widely demonstrated that CD4+ T cells with regulatory function can be harnessed to protect against inflammatory diseases. However, pathways leading to the priming or activation of antigen-specific CD4+ Treg have yet to be fully defined. Here the mechanism for the natural priming of antigen-specific CD4+FOXP3− Treg to a defined self-antigen derived from the conserved framework 3 region of the TCR is presented. This mechanism of CD4+ Treg priming is dependent on APC engulfing apoptotic Vβ8.2+CD4+ T cells, and processing and presenting a conserved TCR-derived antigenic determinant to the CD4+ Treg population. Notably, DC activation is required for

optimal priming of the Treg and CD8α+ DC seem to be most efficient in this priming. It was indicated by earlier studies that Fulvestrant order the CD4+ and CD8+ Treg that suppressed the anti-MBP response in humans and mice were recognizing antigenic determinants associated with the disease-mediating CD4+ T-cell population 30–34. However, due to the lack of knowledge concerning the exact antigenic determinants recognized on the disease mediating cells, the unknown role of APC, and the paucity of defined CD4+ and CD8+

Treg clones, the mechanism of natural Treg priming had not been delineated. Studies presented here show that the naturally occurring TCR-peptide-reactive CD4+ Treg were stimulated upon co-culture with large numbers Thymidine kinase of irradiated spleen cells form naïve H-2u mice (Fig. 1). Stimulation of Vβ8.2 TCR peptide-reactive CD4+ Treg, but not irrelevant CD4+ T cells, indicated that APC (especially DC) within the splenocyte population present an MHC class II-associated TCR peptide. We have recently delineated the mechanism by which DC acquire TCR antigenic determinants from Vβ8.2+ T cells and present another TCR-derived antigenic determinant in the context of the non-classical MHC class I molecule Qa-1 to novel subset of CD8αα+TCRαβ+ Treg 24. As Vβ8.2TCR peptide-reactive CD4+ and CD8αα+TCRαβ Treg work in unison to down-regulate the Vβ8.2+ T-cell response 3, 15, 30, it is not surprising that DC are able to process and present different TCR-derived peptides in the context of class II and class Ib MHC molecules.

When comparing these studies, it also becomes obvious

that the expression of particular genes can be induced or repressed, depending on the antibiotic used (Table 2). PA2367 is downregulated by azithromycin and it is upregulated by imipenem. Similarly, PA3049 is downregulated by azithromycin and upregulated by tobramycin, while PA5216 is downregulated by tobramycin and upregulated by azithromycin (Table 2). The studies by Schembri et al. (2003), GS-1101 concentration Beloin et al. (2004), Ren et al. (2004), Domka et al. (2007) and Hancock & Klemm (2007) revealed that stress-related genes are often overexpressed in sessile E. coli populations compared with planktonic cultures, even in the absence of antibiotics (Wood, 2009). When comparing Ensartinib 40-h-old E. coli biofilms grown in a flow cell with exponentially growing planktonic cultures, Schembri et

al. (2003) noted that 46% (30/65) of rpoS-controlled genes were differentially expressed during biofilm growth (most were upregulated) and an rpoS mutant turned out to be incapable of forming a biofilm in the flow system. In addition, yeaGH were also overexpressed; these genes are rpoS-regulated in Salmonella enterica and may also be associated with a stress response. Ito et al. (2008, 2009b) confirmed that rpoS-mediated stress responses contribute to biofilm-specific phenotypes (including ampicillin resistance). Also, in 8-day-old E. coli TG1 biofilms grown in a microfermentor, stress-related genes were upregulated, including SOS response genes, chaperones, general stress response genes, heat shock proteins and genes involved in DNA repair and envelope stress response (Beloin et al., 2004). This last group of genes includes cpxAR (sensor-regulator components of the cpx Amobarbital two-component system) and the phage shock protein operon (pspABCDE), although no biofilm-related phenotype was obvious in a psp operon mutant. In addition, a TG1 recA mutant was no longer capable of forming mature biofilms, confirming the importance of stress responses in biofilm formation. In E. coli biofilms grown on glass wool, stress genes are also induced, including hslS, hslT, hha, soxS and b1112 (Ren et al., 2004).

hslST are involved in response to heat shock and superoxide stress, while soxS is involved in the response to superoxide. Gene b1112 (also known as ycfR or bhsA), encoding a putative outer membrane protein, plays an important role in stress response and biofilm formation as it mediates the stress response by a mechanism that involves increased synthesis of the signal molecule indole (Zhang et al., 2007; Wood, 2009). Cells in urine-grown biofilms formed by isolates recovered from asymptomatic bacteriuria cases also exhibit an overexpression of stress genes (Hancock & Klemm, 2007). Among the most upregulated genes are cold and heat shock proteins including cpsAGH and hslS, and soxS, yfiD and pphA. The temporal data from Domka et al.

A further limitation to the LCM is that genes expressed in both, FDC and B cells, such as Cd21 cannot be identified by this approach and are therefore missing from Selleckchem C59 wnt the set of genes defined as FDC expressed. The gene expression profile showed that FDC express various extracellular matrix proteins (Fig. 3), known to control the availability of cytokines, chemokines and growth factors 29–31. Indeed, by expressing collagens and fibronectin essential for assembling conduits, FDC may help to regulate the transport of low-molecular-weight proteins 32. The pericellular

localization of biglycan (Fig 4A) is in line with the notion that biglycan functions as an extracellular regulator of cytokines and growth factors 29, 30. Beyond this, FDC may contribute to the mobility of B cells in the GC. Thus, two-photon microscopy has RAD001 molecular weight shown that fibroblastic reticular cells guide the migration of T cell through the T-cell zone 33 and FDC may regulate B-cell motility in a similar way 34, 35. As shown for adhesion molecules such as Vcam-1

and Madcam-1, upregulation of the extracellular proteins Periostin and Coch may also ensure a tight association of B cells with FDC during the GC reaction (Fig. 2B) 2, 36, 37. A more global function of regulating lymphocyte migration within the immune compartments involves sphingosine-1-phosphate (S1P) 38. However, expression of S1P-generating sphingosin-lipases was not detected in FDC networks (no “present” calls) nor in any other compartment of the spleen 39. Instead, our analyses showed that stromal cells in the B-cell follicle express Enpp2 an ectoenzyme that hydrolyzes both lysophosphatidylcholine and sphingosinphosphorylcholine (Fig. 2A) 40. It is most likely that FDC control S1P-mediated egress of lymphocytes from the spleen. Altogether, these findings emphasize that antigen presentation by FDC is only one of the many functions in B-cell

development. Defining a new set of genes specifically expressed in FDC allows us to determine different developmental stages of stromal cell differentiation. In the absence ASK1 of LTα, only weak expression of CXCL13 defines the area where B cells localize (Fig. 4H and Table 1). In CXCR5-deficient mice, LTα is expressed but in the absence of the LTα/CXCL13 feedback-loop the level of LTα is not sufficient for normal development of follicular structures and differentiation of reticular cells into mature FDC 26, 27. Nonetheless, the CXCL13+ stromal cells upregulate the FDC genes BP3, Enpp2 and Bgn (Fig. 4C and G, Table 1). In the SCID mouse, although lymphocytes are missing, the stromal cell compartment does segregate into a BP3hi Bgnhi and a BP3lo Bgnlo area (Fig. 4B). Indeed, with the exception of Serpina1, all of the analyzed FDC genes are expressed also in BP3hi stromal cells, although in most cases at a lower expression level (Fig. 3 and Table 1).