However, it seems most likely that a difference in the immunising regime offers

the most plausible explanation. In the 1980s, 2000 T. circumcincta L3 were given to the previously infected sheep 5 days a week whereas in the recent series of trials this dose was administered only three times per week, i.e. the recent sheep received only 60% of the dose given in the 1980s. Exposure to the heavier immunising infection appeared to confer a more solid immunity to subsequent challenge in yearlings and yet make the lambs more susceptible (Table 2). There was no evidence from the recent PD-0332991 manufacturer trials with the lighter trickle infection to support the idea that one or more components of the immune response

were defective in lambs. This includes examination of the abomasal histology where for example mast cell numbers were in the normal range (data being prepared for publication). We therefore hypothesise that only older, more resilient sheep were able to respond adequately following the heavier trickle, whereas the growing lambs, being less able to cope with the pathological effect of the ALK activation greater parasite load, were only able to mount a weak, relatively ineffective response post-challenge. In conclusion, we suspect that age and acquired immunity in ovine gastrointestinal nematodiasis is more likely to be due to the lack of resilience to infection on the part of lambs than to a specific immunological deficiency. The authors would like to thank Frank Jackson’s laboratory at Moredun for supplying parasites, Stephen Smith and Andy Greer for technical assistance, Mara Rocchi for assistance with the FACS analysis and Jill Sales of BIOSS for statistical Amrubicin analysis. We would also like to thank Roy Davie, David Kennedy and Manus Graham for help with surgery. This work was funded by a Veterinary Training Research Initiative from the Department of Environment, Food and Rural Affairs and by the Scottish Government Rural and Environment Research and Analysis Directorate. “
“Mycobacterium

tuberculosis (TB) often causes persistent infection and many immune cell subsets and regulatory mechanisms may operate throughout the various stages of infection. We have studied dendritic cell (DC) subsets, regulatory T cells (Treg) and the expression of activation and apoptosis markers on CD4+ and CD8+ T cells in blood from patients with active TB (n = 20), subjects with positive QuantiFERON-TB GOLD (QFT) test (LTBI, latent TB infection) (n = 20) before and after 3 months of preventive anti-tuberculous therapy and from QFT-negative controls (n = 28). The frequency of CD4+CD25+CD127− Treg was highest in the group with active TB (P = 0.001), but also increased in the LTBI group (P = 0.006) compared to controls.

45 Androgen affects structural and functional perfection, such as NOS and PDE5 expression and activity of the corpus cavernosum and urinary tract.46,47 Reduced production of testosterone with age contributes to the occurrence of BPH/LUTS.48 Androgen receptors were expressed in the epithelial cells of the urethra and in the bladder of rabbits and in the urothelium, bladder smooth muscle, striated muscle cells of the proximal urethra and in the neurons in the autonomic ganglia of the prostatic plexus of the male rat.49,50 Testosterone and its metabolites maintain the reflex activity in the Erlotinib mouse pelvic part of the ANS in

rats.51 NOS-NO-cGMP pathway is partially androgen-dependent in the rat urinary tract.52 It is suggested that LUTS may be related to low androgen level.21,53 PS-341 Sleep deprivation is a significant problem among adult men who have BPH/LUTS, especially nocturia. After several days of prolonged physical and psychological stress and sleep deprivation, testosterone falls by 70–90%.53 Circulating testosterone levels increase during sleep, which start to rise on sleep onset and peak during the first episode of rapid eye movement (REM) sleep. A rise in testosterone in normal young men during continuous nocturnal sleep began at sleep onset and reached a plateau around

the time of the first REM sleep episode 90 min later.54 Sleep deprivation is a physiological stressor. Therefore, it is not surprising that serum testosterone was altered following sleep deprivation. Sleep deprivation causes secretion of serotonin. Serotonin binds to 5 HT 2 receptor resulting in production of corticotrophin-releasing hormone in Leydig cells. Corticotropin-releasing hormone inhibits cyclic adenosine monophosphate (cAMP) production and subsequent testosterone production.55 Nocturia-induced stress may be a cause of low testosterone. PDE5 mRNA is expressed in the bladder, urethra and prostate. PDE5 I inhibited the contraction of isolated bladder, urethra and prostate strips in an in vitro study.56 These results serve as a motive to attempt PDE5 I in patients with

BPH-induced LUTS. Multiple studies showed that PDE5 I improved BPH/LUTS. However, there has been debate about improvement in Qmax compared with placebo.57–70 of The first choice of management of ED using pharmacotherapy is PDE5 I.71 There have been many clinical studies of sildenafil in BPH/LUTS.57-63 Eryildirim et al.59 found that sildenafil has a positive effect in both LUTS and ED in men with LUTS and ED. The efficacy of tadalafil to relieve LUTS secondary to BPH has been reported in many clinical trials.64–66,70 In a recent clinical study, tadalafil was effective in treating BPH/LUTS. After 12 weeks of medication once daily, tadalafil produced great improvements over baseline in the IPSS, such as 13% for placebo versus 31% for 5 mg tadalafil, and improvement of IPSS was dose-dependent. However, the increase in peak flow rate did not reach statistical significance.

05; Fig. 5). Collectively, there were fewer Th2-promoting cytokine cells (IL-4) than Th1-promoting cytokine cells (IFN-γ). In our previous

study, we developed surface-displayed ApxIIA#5 expressed on S. cerevisiae and full ApxIIA-expressing S. cerevisiae and demonstrated that oral immunization of mice induced antigen-specific immune responses and protection against A. pleuropneumoniae [3, 9]. However, to develop an efficient oral vaccine, further study of the mucosal immune responses induced by transgenic S. cerevisiae was needed. We selected surface-displayed ApxIIA#5 expressed on S. cerevisiae as an oral vaccine for porcine pleuropneumonia. In mice, it has greater specific antibody activities BMN 673 mw than other yeasts, including ApxIIA#5-secreting S. cerevisiae and full-ApxIIA expressing S. cerevisiae [20]. As APCs, DCs induce primary immune responses and have a key role in both innate and adaptive immunity [21]. In adaptive immune responses, the phenotype and function of DCs determine the initiation of tolerance, memory and polarized Th1 and Th2 differentiation [21]. Stimulation of bone marrow-derived DCs with surface-displayed ApxIIA#5

expressed on S. cerevisiae in vitro indicated that this could generally induce secretion Trametinib cell line of the proinflammatory cytokines TNF-α and IL-1β, the Th1-inducing cytokine IL-12p70 and the Th2-inducing cytokine IL-10. Moreover, maturation of the APCs was confirmed by showing upregulation of CD40 and CD86 costimulatory molecules and surface MHC class II, all of which are required

for efficient stimulation of T cells [22]. Mucosal protection requires generation of antigen-specific T cells and antibodies [23]. In addition, following ablation of immune responses after oral and nasal immunization of mice depleted of cDCs in vivo, cDCs are reportedly essential for activation of CD4+ T cells and generation of specific antibodies [23]. In the present study, we demonstrated that surface-displayed ApxIIA#5 expressed on S. cerevisiae helped to improve both systemic and mucosal immune responses in mice by generating antigen-specific antibodies and encouraging proliferation of CD4+ T cells, which were stimulated by DCs activated by oral vaccination. Presentation of ApxIIA on activated DCs to CD4+ T cells from mice in the AMP deaminase vaccinated group elicited specific T-cell proliferation. The induction of ApxIIA-specific T-cell proliferation demonstrated that ApxIIA was indeed presented on DCs and that the orally administered surface-displayed ApxIIA#5 expressed on S. cerevisiae induced cellular immune responses in mice. Both serum Ag-specific IgG and Ag-specific IgA antibody activities increased in the vaccinated group. Furthermore, both Apx-specific IgG and IgA antibody-producing cells in the PP, LP and SP were significantly more numerous in the vaccinated group than in the control group.

NF-κB is an essential transcription factor for multiple genes related to the immune response www.selleckchem.com/products/Trichostatin-A.html and development [70, 73]. Previous studies with

dexamethasone, a multifunctional steroid hormone that inhibits NF-κB function among many other effects, demonstrated inhibition of phagocyte NADPH oxidase genes (CYBB and NCF1) at the transcriptional level in THP-1 myelomonocytic cells [74]. Studies investigating the functional role of NF-κB in respiratory burst activity and in expression of CYBB, CYBA, NCF1 and NCF2 in U937 cells stably transfected with a repressor of NF-κB (IkBα-S32A/S36A) demonstrated significantly lower superoxide release and lower CYBB and NCF1 gene expression compared to control U937 cells [75]. Hereditary defects affecting components involved in NF-κB activation can result in heterogeneous diseases including a clinical syndrome of anhidrotic ectodermal dysplasia (EDA), with or without associated lymphoedema, osteopetrosis or immune deficiency

(EDA-ID). It may be inherited in either X-linked Mendelian recessive or autosomal dominant patterns. The former derives from mutations in the gene encoding NEMO, IKKG or IKBKG (OMIM # 300291). The latter, rarer disease is caused by a mutation in the IKBA gene (OMIM # 129490), in which substitution or deletion of the two critical serine residues in the N-terminus make the protein resistant to degradation and therefore a dominant negative that prevents NF-kB activation [76, 77]. In these syndromes, selleckchem mutations affecting the NF-κB pathway lead to a CGD-like functional defect in myeloid cells, in addition to the better-known defects in the acquired immune system, and may contribute to the severe immunodeficiency [75]. Future studies

examining primary phagocytes from EDA-ID patients for respiratory burst and bactericidal activity will help to correlate specific NF-κB pathway mutations with biochemical defects, as well as with agents causing infections. SSR128129E Another primary human immunodeficiency occurs in patients with mutations in the IRAK4 gene, a key early enzyme in the Toll-like receptor/IL-1R/IL-18R signalling pathway (OMIM # 610799). These patients suffer from recurrent, life-threatening pyogenic bacterial diseases, typically caused by Streptococcus pneumoniae [78–80]. IRAK4 deficiency, caused by homozygous or compound heterozygous mutations, is rare (approximately 28 cases reported worldwide) [81], but the severe presentation may result in significant underreporting because of early death. With early recognition and appropriate clinical management, the susceptibility to infection of IRAK4-deficient patients typically decreases with age, suggesting that adaptive immunity progressively compensates for this innate immune defect [81].

B6Idd3 mice exhibit an increased suppressor activity compared to NOD CD4+CD25+ T cells. To determine whether the protection mediated by NOD.B6Idd3 CD4+CD25+ T cells was due to quantitative or qualitative differences within the pool of CD62LhiFoxP3+Tregs, the suppressor

activity of these immunoregulatory effectors was tested in vitro. CD62Llo- and CD62Lhi-expressing CD4+CD25+ T cells were FACS sorted from the PaLN of 16-wk-old NOD.B6Idd3 and NOD female mice, and then cultured at various ratios with naïve CD4+ T cells from the spleen of NOD mice. As expected, CD62LloCD4+CD25+ T cells from either NOD.B6Idd3 or NOD female mice were inefficient at suppressing proliferation of the stimulated CD4+ T cells (Fig. 5D). On the other hand, CD62LhiCD4+CD25+ T cells effectively suppressed proliferation of the responder CD4+ APO866 concentration T cells. Furthermore, no significant difference in suppressor activity of NOD.B6Idd3 and NOD

CD62LhiFoxP3+Tregs was detected (Fig. 5D). Therefore, the enhanced suppressor activity detected in the PaLN of NOD.B6Idd3 mice is due to an increased number of CD62LhiFoxP3+Tregs, consistent with results obtained in the above co-adoptive transfer experiments (Fig. 5C). Since IL-2 selleck compound secretion by conventional T cells is limited in NOD mice compared with NOD.B6Idd3 animals (Supporting Information Fig. 1) 38, then increasing the level of “endogenous” IL-2 would be expected to enhance the frequency of CD62LhiFoxP3+Tregs in vivo. To test this hypothesis, 10-wk-old NOD female mice were injected intramuscularly with a doxycycline inducible adeno-associated virus (AAV) recombinant encoding IL-2 (AAV-Tet-IL-2). No difference was detected in the frequency of CD4+CD25+Foxp3+ T cells

in AAV-Tet-IL-2 treated but uninduced NOD mice or animals left untreated (Fig. 6A and B). In contrast, NOD mice treated with AAV-Tet-IL-2 and in MycoClean Mycoplasma Removal Kit which IL-2 transgene expression was induced exhibited an increased frequency of CD4+CD25+Foxp3+ in all tissues tested (Fig. 6A and B), and showed a significant increase in CD62Lhi-expressing CD4+CD25+Foxp3+ T cells in the PLNs (Fig. 6C). Furthermore, addition of IL-2 to FACS-sorted CD62Llo-expressing CD4+CD25+ T cells upregulated expression of CD62L in vitro (Fig. 6D). These results indicate that: (i) IL-2 availability in vivo regulates the frequency of CD62LhiFoxP3+Tregs, and (ii) IL-2 can “convert” CD62LloFoxP3+Tregs into CD62LhiFoxP3+Tregs in vitro. Analyses of NOD mice congenic for protective Idd3 intervals have shown that aberrant expression of IL-21 and IL-2 influences various aspects of β-cell autoimmunity in NOD mice 34–38. Increased expression of IL-21 and IL-21R by T cells is associated with enhanced development of pathogenic T effectors in NOD mice through, for instance, disruption of T-cell homeostasis 34, 36, 40–42. IL-21 has also been reported to render conventional T cells resistant to the suppressor effects of FoxP3+Tregs 43, 44.

detected circulating T cells specific to gTG in CD patients without a gluten challenge [14]. These cells were detectable in the peripheral blood of more than half of adult CD patients on a gluten-free diet, but not detectable in healthy controls. Importantly, all the studies outlined above have analysed T cell responses in adult CD patients, whereas gliadin-specific Enzalutamide T cell responses in children with CD are explored far less widely. One study analysing intestinal CD4+ T cell responses suggested that the responsiveness to gliadin epitopes in paediatric CD patients differs from that found in adults [15]. Currently, it is unknown whether gliadin-specific T cells

are also detectable in the peripheral blood of children with

newly diagnosed CD. However, it is conceivable that the immune response in children at diagnosis represents an earlier and more active form of the disease, as responsiveness has not waned due to antigen elimination associated with a gluten elimination diet. In the present study, we used the CFSE dilution method Sotrastaurin manufacturer to detect peripheral blood gliadin-specific T cells in children undergoing diagnostic small intestine biopsy for the diagnosis or exclusion of CD. In recent years, there has been increased debate on whether diagnostic biopsy is warranted in symptomatic children, and in some cases diagnostic criteria have been suggested based solely on antibody findings [16]. Therefore, our aim was to clarify the potential value of the detection gliadin-specific T cells in the periphery in supporting the diagnosis of CD. For this, we analysed proliferative

responses to both native gliadin and gTG as well as two synthetic peptides containing previously reported immunodominat epitopes of α-gliadin. We also characterized the memory phenotype and the expression of β7 integrin, a gut-homing molecule, on gliadin-specific T cells. Twenty Finnish children (10 girls and 10 boys) with newly diagnosed CD were included into this study. Blood samples were taken during the clinical visit where the CD diagnosis was confirmed with capsular Fluorometholone Acetate endoscopy, before the child was started on a gluten-free diet. In total, 19 of these 20 children were tested positive for tissue transglutaminase antibodies (TGA) (Celikey; Phadia, Freiburg, Germany); one of the children was not tested for TGA but was highly positive for endomysial antibody. The diagnosis of CD was set based on histological findings in the duodenal biopsy. Sixteen of the children (80%) were HLA-DQ2-positive, three were HLA-DQ8-positive (15%) and the HLA typing was not carried out on one of the children. The median age of children with CD was 8·3 years (range 3·6–14·8). The control group comprised 64 healthy children (27 girls and 37 boys) carrying the CD-associated HLA alleles.

Unlike MHC-restricted T cells, iNKT selleck chemical cells recognize lipids presented by CD1d. The iNKT cells can produce various types of cytokines, rapidly and at high levels, which is why they are part

of the innate immune system. They are often the first T cells to be activated and their rapid cytokine production means that they potently transactivate other immune cells. Therefore they are an important bridge between the innate and adaptive immune system, and can orchestrate or skew an immune response depending on the array of cytokines that they produce. Importantly, we have identified a striking role for iNKT cells in regulating adipose tissue inflammation, metabolism and weight control. This review will discuss the series of findings on adipose iNKT cells that have emerged in recent years, the controversies in the metabolic phenotype of iNKT-deficient mice, and the exciting potential they may hold for manipulating

the adipose immune system in obesity. Invariant NKT cells are a specialized subset of innate T cells that are highly conserved in mammals.[4] Adaptive T cells see more recognize peptides presented by MHC molecules, but iNKT cells recognize lipids presented by CD1d molecules.[5] CD1d is a non-polymorphic MHC class I-like molecule that is expressed on antigen-presenting cells such as dendritic cells, macrophages and B cells. CD1d is also expressed on non-haematopoietic cells including hepatocytes[6] and adipocytes.[7, 8] The iNKT cells recognize their lipid ligands on CD1d through their semi-invariant T-cell receptor (TCR).[9-11] In mice, iNKT cells express TCRs comprising a Vα14-Jα18 chain paired with a limited Vβ chain repertoire (Vβ2, Vβ7, Vβ8.1,

Vβ8.2 or Vβ8.3).[12, 13] In humans, iNKT cells express Vα24-Jα18 chain paired almost exclusively with a Vβ11 chain.[14] Like iNKT cells, CD1d is highly conserved in mammals.[15] There is a large degree of functional and structural similarity between the TCRs that are expressed by human and mouse iNKT cells, to the degree that some lipids presented by human CD1d can be recognized by murine iNKT cells and vice versa. The first lipid to be identified as an antigen for iNKT cells was α-galactosylceramide (αGalCer), which remains the most potent activator of Isoconazole iNKT cells. αGalCer was discovered during a screen of marine sponges for anti-cancer activity in 1997, and is derived from marine sponges, or possibly the microbes that inhabit them, and was synthetically modified to be a potent pharmacalogical activator of iNKT cells. The search for physiologically relevant lipids from pathogens or self-lipids recognized by iNKT cells is under intense investigation, and recently there have been many breakthroughs identifying endogenous and microbial lipid ligands. Endogenous lipids include isoglobotrihexosylceramide,[16] glucosylceramide,[17] lysophosphatidylcholine[18] and ether-bonded phospholipids derived from peroxisomes.

Moreover, infection of BMDCs

with a plasmid-cured apathogenic Yersinia enterocolitica strain lead to DC Rucaparib mw swelling in a MOI (multiplicity of infection) dependent manner (data not shown) indicating that bacterial LPS is responsible for DC swelling in response to contact with bacteria. Additionally, LPS-induced DC swelling was dependent on the LPS concentration used (data not shown). Moreover, we found that LPS-induced DC swelling (Fig. 1a) and CCL21-directed migration (Fig. 1b) were impaired in TLR4-deficient DCs when compared to WT DCs. These results indicate that the observed cell swelling is critically dependent on TLR4 signaling upon LPS binding. Our results are supported by another in vitro study demonstrating that stimulation of TLR4 by LPS, but neither stimulation of TLR2 by PamCys or heat-killed gram-positive bacteria nor activation of BMDCs by different cytokines (TNFα, IL-10) induce the loss of podosomes, and thereby enhance the migratory capacity of DCs [6]. However, it cannot completely be excluded that LPS-induced DC swelling occurs independently of DC migration. Moreover, cell swelling itself is not causative for DC migration since BMDCs treated with 20% H2O for 4 hr did not migrate along a chemokine gradient (data not shown). It has been described

that treatment with LPS for 24 hr increases the expression of CCR7, the receptor of the chemokines CCL19 and CCL21, on DCs [22]. Hence, possibly differences in the CCR7-expression on DC between WT and TLR4−/− DC might affect CCL21-directed learn more migratory activities of these two cell types. As a consequence, BMDCs of WT and TLR4−/− mice were treated or not with LPS for 4 hr, double-stained with fluorescent antibodies against CD11c and CCR7, respectively, and analyzed by flow cytometry (data not shown). No differences were detected in the CCR7 expression rates between WT and TLR4-deficient DC kept in medium without LPS (12.5 ± 3.4% why vs. 12.4 ± 4.3%). However, after incubation with LPS (500 ng/mL) for 4 hr, CCR7 expression on DC was higher in WT than in TLR4−/− DCs (25.2 ± 4.8% vs. 17.4 ± 4.0%) suggesting that the LPS-induced

increase in CCR7 expression in WT DC contributes to LPS-induced migration. Intracellular Ca2+ acts as a key regulator of actin assembly thereby affecting the migratory activity of DCs [19]. For example, within minutes after exposure of DCs to gram-negative bacteria or LPS the cytosolic Ca2+ levels increase involving both mechanisms, entry of extracellular Ca2+ and the release of Ca2+ from intracellular stores [7, 20]. Elevated Ca2+ in turn causes extensive actin-based cytoskeletal rearrangement including loss of podosomes thereby facilitating the conversion of DCs to a migratory phenotype [6]. After treatment of DCs with LPS, we observed an increase in [Ca2+]i within 30–120 min (Fig. 2b). Increased [Ca2+]i in migrating cells may result from activation of mechanosensitive Ca2+ channels by the growing lamellipodium at the front part and gradual cell swelling [19].

8 years at age 60) and increasing. Further analysis is required to better define the relationship between improving survival in the dialysis and general populations. 237 THE PREVALENCE AND IMPACT OF PRURITIS IN A DIALYSIS POPULATION J HOLT1,3, S HERATH1, A LEE1,2, K MURALI1,3, M LONERGAN1,2,3, K LAMBERT1 1Wollongong Hospital, NSW; 2Shoalhaven District Memorial Hospital, Nowra, NSW; 3Shellharbour Hospital, NSW, Australia Aim: To

determine the prevalence and impact of pruritis in our dialysis population. Palbociclib clinical trial Background: Itching is very common in patients who are on dialysis. Literature regarding the impact of pruritis on quality of life and intensity of itch is limited. Methods: The project was designed as a questionnaire.

Local Ethics approval was obtained. All patients on dialysis for ≥ 3 months area wide were eligible to participate. Participants were approached by an investigator and asked a series of questions. Routine blood results and lists of medications were also recorded. Participants were asked to rate their itch in 3 different ways: Visual Analogue Scale Lund Browder chart to estimate total body surface area involved Impact of itch on quality of life Results: 127 patients were recruited over a 3 month period.114 patients were on haemodialysis and 13 patients on peritoneal dialysis. The mean dialysis vintage was 66.9 months and the mean CB-839 duration of HD per week was 14.6 hours. 83 patients reported suffering with itch (63%) and, of these, only 35 (42%) had informed their renal physician. The mean Visual Analogue reading was 31.7 and this method of rating itch did not correlate with any of the usual biochemical parameters. The mean body surface area involved was 18% and did not correlate with the analogue reading. The presence of itch significantly impacted on the ability to fall asleep, oxyclozanide a person’s appetite and their mood, with 69% reporting feeling

unhappy either all or most of the time. Conclusions: Itch is common in patients undergoing dialysis and has a significant impact on quality of life. The majority of patients do not report their symptoms. 238 NEUTROPHIL-LYMPHOCYTE RATIO AS A MARKER OF INFLAMMATION AND PREDICTOR OF MORTALITY IN PATIENTS WITH END-STAGE KIDNEY DISEASE BL NEUEN1, N LEATHER2, A GREENWOOD2, R GUNNARSSON2, JP KILLEN1, RA BAER1, A NIGAM1, I ISMAIL1, L BERLUND1, ML MANTHA1 1Department of Renal Medicine, Cairns Hospital, Cairns, QLD; 2School of Medicine and Dentistry, James Cook University, Cairns, QLD, Australia Aim: To examine the value of neutrophil-lymphocyte ratio (NLR) as a marker of inflammation and predictor of all-cause mortality in patients with end-stage kidney disease (ESKD). Background: NLR is a marker of systemic inflammation that has been shown to predict mortality in patients with coronary and peripheral vascular disease. In contrast to albumin, NLR is unlikely to be affected by nutritional status. Its prognostic value in ESKD patients is unclear.

2). The early responding C12Id+ HA-specific B cells were also not significantly different with regard to expression of CD24, one of the markers identified by Linton et al. 41 to correspond with extrafollicular foci development, although we measured CD24 expression with an anti-CD24 mAb different from that used by that earlier study (data not shown). Thus, LN seem to lack a specific resident B-cell subpopulation comparable to the MZ B-cell population in the spleen that can facilitate rapid responses to early blood-borne infection. Instead,

follicular (C12Id+ HA-specific) B cells provide this rapid, Ibrutinib price strong (Fig. 1) and protective 2 extrafollicular B-cell response (Fig. 3). Various models have been proposed to explain the regulation of extra- versus intra-follicular B-cell responses 22, 26, 39–41, 46. The influenza virus model system described here and available tools to study the C12Id-specific responses provide an excellent opportunity to further analyze this important differentiation process in vivo in

the context of an infection. Our study identifies C12Id-expressing HA-specific B cells as predominant contributors to a strong extrafollicular B-cell response in regional MedLN, the site of much of the early Ab response to this virus. Predominant R428 in vitro participation of the C12Id-expressing HA-specific cells in extrafollicular responses is consistent with earlier findings that failed to find any mutated C12Id-sequences among HA-specific B cells 27, i.e. these cells showed no signs of affinity maturation. However, we show here that while C12Id+ cells vigorously participate in extrafollicular foci responses (Fig. 3), they can also initiate

germinal centers (Fig. 4). While we cannot completely rule out that C12Id+ B cells that mutated their BCR might have lost the idiotope that allowed us to stain these cells for FACS analysis, Cell press the earlier extensive sequence studies on B cells from mice at various times after immunization (26), make this trivial explanation somewhat unlikely. Given the recent studies by Paus et al. 22 that implicated BCR-affinity for antigen in the selection process, our studies might suggest that high-affinity interactions with antigen are a necessary, but likely not sufficient, signal for extrafollicular foci development as C12Id+ HA-specific cells are able to also initiate germinal centers (Figs. 3 and 4). Failure to expand this germinal center response during early infection, rather than an inability to initiate it, might result in the irregular kinetics and small frequencies of C12Id+ germinal center B cells observed here (Fig. 4). This interpretation is not only consistent with the presented data, but also with earlier studies using the (4-hydroxy-3-nitrophenyl) acetyl system, which demonstrated that extrafollicular foci and germinal center B cells can have a common precursor 25, 26, 39. The vigorous infection-induced extrafollicular foci response is likely supported and modulated by external signals.