To understand how GLA

To understand how GLA click here works, we studied DCs directly from vaccinated mice. Within 4 h, GLA caused DCs to upregulate CD86 and CD40 and produce cytokines including IL-12p70 in vivo. Importantly, DCs removed from mice 4 h after vaccination became immunogenic, capable of inducing T-cell immunity upon injection into naïve mice. These data indicate that a synthetic and clinically feasible TLR4 agonist rapidly stimulates full maturation of DCs in vivo, allowing for adaptive immunity to develop many weeks to months later. The engineering of subunit

proteins to produce protective vaccines against infectious diseases and cancer represents an exciting new area of research. Such vaccines can be injected repeatedly yet offer safety and ease of production 1. However when given alone, protein vaccines often lack the necessary immunogenicity to induce a

protective response 2–4. The addition of adjuvants provides a means to initiate, direct, and sustain the immune response 5. Despite the success of currently approved adjuvants for generating protective antibody responses to viral and bacterial infections, there is still no effective adjuvant to generate strong T-cell immunity. Many components that activate the innate immune system are being tested, particularly synthetic compounds that are meant to mimic the presence of a microbe, but the CH5424802 research has emphasized studies with in vitro systems or transgenic mouse models 6–12. DCs are the main antigen presenting cells for initiating immunity. The engagement of innate signaling receptors on DCs leads to cytokine and chemokine secretion, one consequence being the upregulation of costimulator molecules like CD86, to drive T-cell priming 13. Cytokines secreted by DCs further polarize the T cell to produce protective or “effector” products like IFN-γ 14. Also microbial products

trigger DC migration to the T-cell areas of lymphoid organs, an effective site to select rare clones of antigen-specific, naïve T cells from the recirculating repertoire 15, 16. This intricate differentiation process that allows DCs to initiate immunity is called maturation. Maturation has generally been defined by high expression of costimulatory Thalidomide molecules and production of inflammatory cytokines in vitro, but to understand adjuvant action, it is necessary to study their effects on DCs in intact animals and, in addition to monitoring changes in DC phenotype (“phenotypic maturation”), prove that the DCs have become immunogenic or “functionally mature” for primary immune responses in vivo. DCs express a variety of innate receptors, including toll-like receptors (TLRs) that signal the presence of microbial and viral products and trigger DC maturation 14. Lipopolysaccharide (LPS), found in the outer membrane of Gram-negative bacteria, is a natural agonist for TLR4 signaling of DCs 17. However, the toxicity of LPS precludes its use as a vaccine adjuvant in humans 18, 19.

The questions yet unanswered by all the studies are: best source

The questions yet unanswered by all the studies are: best source of MSC, the timing of infusion, dose of infusion, site of infusion and efficacy in terms of recovery Roxadustat solubility dmso and/or minimization of immunosuppression. Trivedi et al. have probably answered most of the queries haunting transplanters for the last 50 years. We have shown that

combined adipose tissue-derived MSC and HSC have been useful in reaching the Utopian dream of tolerance. In one of our studies of 606 living donor RT we have addressed several questions haunting transplanters. We have deleted rejecting T and B cells by non-myeloablative conditioning of total lymphoid irradiation (200 cGY × 4 or 5 days) and/or Bortezomib, 1.5 mg/kgBW in four divided doses, every third day, Cyclophosphamide, 20 mg/kg body weight and rabbit antithymocyte globulin, 1.5 mg/kg body weight. We infuse combined adipose tissue-derived MSC and HSC in portal and thymic circulation, since liver is the most tolerogenic organ due to its microanatomy and various functional aspects.[31, 32] Cells entering thymus undergo both positive and negative selection, resulting in T cells with a broad range of reactivity to foreign antigens but with a lack of reactivity to self-antigens. It is also a source of a subset

of regulatory T cells that inhibit auto-reactivity of T-cell JQ1 price clones that may escape negative selection. Hence, thymus is Resminostat believed to be essential for induction of tolerance. We have also observed that stem cells when infused before solid organ transplantation help in blocking direct and indirect pathways of rejection. Furthermore, although there is no definite evidence of their grafting we have seen maintenance

of T-regulatory cells recruited by MSC, which help in sustaining tolerance. In addition, with better HLA matching, the weaning off immunosuppression becomes safer. We have observed in our pilot study of two patients that post-transplant infusion of MSC can lead to acute rejection (unpublished data) hence the best timing of MSC infusion is before organ transplantation and preferably 10 days before transplantation as depicted in Figure 1. Infections remain a major challenge for all transplantations especially in developing countries where social, economic and environmental conditions are far from health-promoting. Therefore the major cause of death is infections with 15% developing tuberculosis, 30% cytomegalovirus, and nearly 50% bacterial infections in developing countries.[33] The prevalence of post-transplant tuberculosis in India is reported to be the highest (12 to 20%) in the world, and the mortality among those afflicted is high at 20 to 25%.

The ISDR interacts with PKR and regulates replication of HCV in v

The ISDR interacts with PKR and regulates replication of HCV in vitro (28).

Mutations in the ISDR affect the interaction with PKR and may inhibit viral replication. In the case of the IRRDR, the molecular mechanism underlying the possible involvement of this region in IFN responsiveness of the virus click here is still unknown. The significant difference among IRRDR sequence patterns may suggest genetic flexibility of this region. Thus, changes in the IRRDR might be capable of modulating intracellular antiviral activity, or maybe the genetic flexibility of this region is accompanied by compensatory changes elsewhere in the viral genome and these compensatory changes affect overall viral fitness and responses to IFN therapy (29–31) When we investigated the impact of various sequences patterns at positions 70 and 91 of the core protein, we observed that single point mutation at position 70 (Gln70 PI3K inhibitor vs non-Gln70) was the only factor that significantly

influenced treatment responses. This result is consistent with recent reports, including a recent multi-center study in Japan that identified Gln70 as a predictive factor for poor responses to PEG-IFN/RBV treatment (14, 13, 30). The core region of HCV interacts with several host factors and modulates expression of numerous genes, including down-regulating IFN-induced antiviral genes, thus inhibiting the antiviral action of IFN (32, 33). Therefore, it would also be interesting to investigate the impact of polymorphism, both at position 70 and of NS5A, on HCV pathogenesis and IFN sensitivity. Multivariate logistic regression analysis of all available data, including those of NS5A and core polymorphisms in this study and the data on NS3 polymorphism in the same patient cohort published elsewhere (16), identified IRRDR ≥ 4 and group A of NS3 as independent viral factors that are significantly associated with a SVR, and IRRDR ≤ 3,

and Gln70 of the core protein as independent factors significantly associated with a null response (Table 5). No combinations of these criteria produced a more significant correlation with virological responses to PEG-IFN/RBV therapy (data not shown). In conclusion, the present results demonstrate that sequence heterogeneity of NS5A, Casein kinase 1 especially in IRRDR and ISDR, and a single-point mutation at position 70 of the core protein of HCV-1b are significantly correlated with virological responses to PEG-IFN/RBV therapy. Also, the results emphasize the possible functional importance of NS5A and core protein in regulating viral responsiveness to PEG-IFN/RBV. This study was supported in part by Health and Labor Sciences Research Grants from the Ministry of Health, Labor and Welfare, Japan, and a Science and Technology Research Partnership for Sustainable Development grant from the Japan Science and Technology Agency and Japan International Cooperation Agency.

Because FACS- and PCR-based analyses examine T-cell clonality fro

Because FACS- and PCR-based analyses examine T-cell clonality from different aspects, the future development of tetramer-based FACS on Leishmania Ag-specific CD4+ T cells would be helpful for accurate assessment.

Nevertheless, results from these studies clearly indicate the magnitude of CD4+ T-cell activation induced by different Leishmania species correlates with infection outcome. Having demonstrated strong T-cell activation and IFN-γ production in Lb infection, we then examined whether pre-infection with Lb could provide cross-protection against secondary La infection via an enhanced T-cell activation. We showed that this cross-protection correlated nicely with the increased T-cell activation and IFN-γ production from CD4+ T cells (Figure 3), a finding consistent with previous studies on L. major PI3K phosphorylation pre-infection followed with a secondary infection with La or L. mexicana parasites (24,32). Again, the tested 4 Vβ subset contributed Decitabine order comparably to IFN-γ production. Because the quality or multifunctional

capacity of CD4+ T cells is a crucial determinant in vaccine-mediated protection against L. major (33) and malaria (34), we investigated the production of several cytokines from CD4+ CD44+ effector T cells in La- or Lb-infected mice. It was evident that CD4+ CD44+ T cells derived from Lb-infected mice tended to produce high levels of IFN-γ, but low levels of IL-10 and IL-17 (Figure 5a), and that this Th1-favoured response was maintained even when cells were stimulated in vitro with La antigen (Figure 5b). Therefore, the healing P-type ATPase from control of Leishmania infection requires sequential events that include efficient dendritic cell activation (5), adequate innate responses (12) and activated Th1-type responses to a relatively broad spectrum of parasite antigens. Notably, the adoptive

transfer of Lb-specific CD4+ T cells into naïve mice failed to protect mice against the subsequent La infection (data not shown), a finding consistent with a previous report showing the lack of protection against L. mexicana infection following the adoptive transfer of L. major-specific CD3+ T cells (24). The reasons for this lack of cross-protection by cell transfer alone may include the maintenance of effective Th1 responses and cell recruitment in the recipients, as well as the unique features of L. amazonensis and L. mexicana parasites (35). In summary, our comparative analyses of CD4+ T cells in different models of cutaneous leishmaniasis indicate that Leishmania infection does not change the diversity of the TCR Vβ repertoire in either self-healing or nonhealing model and that multiple TCR Vβ CD4+ T cells contribute collectively and comparably to IFN-γ production.

The concept that IL-1 possessed these seemingly unrelated propert

The concept that IL-1 possessed these seemingly unrelated properties was diagramed in 1984 (4 and Fig. 1), without the benefit of recombinant IL-1 to validate the concept. The scientific community, being skeptical of the concept that a single small protein could have such a spectrum of activities, demanded confirmation with recombinant IL-1. Following the isolation of the cDNA for IL-1α 5 and IL-1β 6 in 1984, studies using the recombinant forms confirmed the growing list of inflammatory properties of IL-1. Indeed, recombinant GPCR Compound Library IL-1α or IL-1β provided ample evidence for the broad role of IL-1 in health as well as disease (Fig. 2) The availability of recombinant

forms also allowed for the development specific assays such as radioimmunoassays and later ELISAs. These assays changed how many viewed cytokines since the immunoassays liberated the investigator

from the non-specific bioassays that had dominated and confused the field for 20 years. The specific assays now told another story and that was the ability to follow a disease process or a therapy in terms of changes in cytokine levels. However, the greatest contributions of the recombinant forms of IL-1 were the responses they triggered upon administration to humans. Cancer patients undergoing bone marrow transplantation were injected with either IL-1α or IL-1β to stimulate hematopoiesis Table 1 summarizes the human responses observed, and physiologic responses such as fever following injection of 10 ng/Kg IL-1α or IL-1β match those observed using Y-27632 ic50 purified human leukocytic pyrogen injected into rabbits in 1977 2. Next in the history of IL-1 was the identification of the naturally occurring and specific inhibitor of IL-1 activity 7–9, later found to be the IL-1 receptor antagonist (IL-1Ra). IL-1Ra was developed into a therapeutic (anakinra) and tested in humans. Anakinra is a pure receptor antagonist binding tightly to the type I IL-1 receptor (IL-1RI) and preventing Aspartate activation of this receptor by either IL-1β or IL-1α. Approved for treating patients

with rheumatoid arthritis, the use of anakinra validated the importance of IL-1 in a broad spectrum of inflammatory diseases. More recently, soluble receptors for IL-1 (rilonacept) and human mAbs to IL-1β (canakinumab and Xoma 052) have been used to neutralize IL-1β specifically. In most reports, summarized in Table 2, there is a dramatic, rapid and sustained improvement in patients following a reduction in IL-1β activity. Thus, from clinical studies using IL-1β neutralization, one concludes that this cytokine should be considered a gatekeeper of inflammation. The term was first used to describe a rare disease characterized by recurrent bouts of fever and systemic inflammation due to a mutation in the coding region of the p55 TNF-receptor 10. The disease was traditionally called Familial Hibernian Fever but is now called TNF-receptor-associated periodic syndrome or TRAPS.

[85-88] Other analogues of αGalCer that are able to skew conventi

[85-88] Other analogues of αGalCer that are able to skew conventional CD4+ T-cell responses more towards either a Th1- or a Th2-like profile will be introduced into clinical studies. In the near Selleck BAY 73-4506 future, it may be possible to differentially activate or inhibit type I and type II NKT cells for the development of novel immunotherapeutic protocols in the treatment

and prevention of autoimmune diseases. Mechanisms by which NKT cell subsets modulate immunity generally follow events and their interactions with other immune cells after activation by their respective lipid antigens, e.g. αGalCer and sulphatide for type I and type II NKT cell subsets, respectively. As DCs play a crucial role not only in the activation of NKT cells but also may be central to their role in the regulation of immune responses, we will first consider NKT–DC interactions and their control of NKT cell-mediated modulation of

autoimmune disease. The advent of intravital imaging now enables the cell dynamics and function of T-cell–DC interactions to be investigated in vivo. Considerable new information provided by the application of 2P microscopy has been reported about the cellular and molecular dynamics of conventional CD4+ and CD8+ T-cell–DC interactions in vivo.[51, 54] While NKT–DC interactions are also central to the regulation of many immune responses find more and diseases, less is currently known Calpain about the dynamics of movement, recirculation and interaction between NKT cells and DCs in vivo.[51, 54] Some recent observations made using in vivo imaging of NKT–DC interactions are presented in Table 6. A key finding is that bidirectional NKT

cell–DC interactions can elicit and amplify innate and adaptive immune responses. Hence, intravital imaging has identified a central role for NKT cells in the context of other immune cells during various immune responses.[51, 54] This further underscores the importance of learning more about different NKT cell subsets and developing more experimental approaches to track these NKT cell subsets by in vivo imaging. In such studies, it is essential to monitor before and after antigen stimulation: (i) the tracking patterns of type I and type II NKT cells from blood into peripheral tissues (e.g. lymph nodes, spleen, liver), (ii) the differences in the number, time and stability of encounters of these NKT subsets with DCs, (iii) the time and sites of migration of these subsets after DC interaction, and (iv) these various parameters in environments of health (e.g. normal disease-free mouse strains) or disease (e.g. mouse strains that develop different autoimmune diseases, as described below).

We, therefore, performed a time kinetics study for MAPK activatio

We, therefore, performed a time kinetics study for MAPK activation after bacterial challenge of monocytes in the presence or absence of n-butyrate. Phosphorylation of extracellular signal-regulated kinase 1/2 and p38 could be demonstrated after 30 min stimulation with LPS whereas Jun N-terminal kinase was not affected. Addition of n-butyrate to LPS did not

lead to a further up-regulation of any MAPK activation pathways (Fig. 6a, same results after 5 and 15 min). Addition of the specific MAPK/ERK kinase (MEK)1/2 inhibitor UO126 as well as p38 inhibitors SB203580 and SK86002 blocked phosphorylation of the respective MAPK after stimulation with LPS and after stimulation with LPS plus n-butyrate (data not shown). Similar results LDK378 in vivo were obtained, when MAPK activation was assessed by intracellular staining and Western blotting (data not shown). Since COX-2 expression also largely depends on NF-κB signalling[19-21] we elucidated the impact of n-butyrate on several components of this pathway GW572016 after LPS activation. We, therefore performed Western blot analyses for NF-κB activation after

bacterial challenge of monocytes in the presence or absence of n-butyrate. Results of these experiments clearly showed that phosphorylation and degradation of IκB, as well as phosphorylation of p50 and p65, after stimulation with different concentrations of LPS was unaffected by n-butyrate (Fig. 6b). We next assessed DNA binding activity of NF-κB p50 and NF-κB p65 after stimulation with LPS in the presence or absence of n-butyrate and

found that n-butyrate treatment had an inhibitory effect on DNA binding in monocytes (Fig. 6c). Interestingly, phosphorylation of p105, a marker for alternative NF-κB pathway activation, was also unaffected by n-butyrate (Fig. 6b). These findings indicate that Alanine-glyoxylate transaminase n-butyrate appears to differently interfere with early and late phases of NF-κB signalling and might even have the converse effect on different NF-κB signalling pathways. Many recent studies highlight the immunomodulatory potential of the SCFA n-butyrate in various immune cell populations like monocytes, dendritic cells, T cells and mast cells as well as epithelial cells.[5, 8-10, 12, 13, 22-25] As its presence is largely restricted to the gastrointestinal tract and immunological features of this region have striking similarities to the effects brought about by this physiologically occurring substance there is great interest in its molecular mode of action, which, so far has been poorly understood. In this study, we show that the bacterial metabolite n-butyrate substantially influences the monocytic gene regulation of several members of the eicosanoid pathway and potentiates the release of prominent prostaglandins and leukotrienes.

jejuni were isolated from patients with enteritis (food poisoning

jejuni were isolated from patients with enteritis (food poisoning); of those, 14 strains belonged to ST21 (CC21), ST22 (CC22), ST42 (CC42), ST400 (CC353), ST407, ST545 (CC22), ST922, ST4052

(CC353), ST4060 (CC460), ST4063 (CC283) and ST4108 (CC607) [12]. Seven strains of C. jejuni (serotype Penner HS:19) were from patients with GBS and belonged to ST22 (CC22), ST2140 (CC574), ST4049 (CC464), ST4051 (CC22), and ST4053 (CC353) [12]. C. jejuni also included strain ATCC33560. Five strains of C. coli were isolated from patients with enteritis and belonged to ST860 (CC828), ST1068 (CC828), ST1593 (CC828), and ST4059 (CC828) [12]. Four strains of C. fetus and two strains of C. lari, which were isolated from the feces of patients with food poisoning, were kindly provided by Dr Akemi Kai (Tokyo Akt activity Metropolitan Institute of Public Health, Tokyo, Japan). V. cholerae O1 strain EO8 [13], V. cholerae O139 strain T16 [14], and H. pylori strain C7M [15] were also assessed. All bacterial strains were stored at −80°C in 3% skim milk (Difco; Becton Dickinson, Franklin Lakes, NJ, USA) supplemented with 5% glucose (Difco). The other bacterial strains used were from our laboratory stock. For Campylobacter growth, blood-agar plates (trypticase soy agar supplemented with 5% sheep blood; Becton Dickinson, Tokyo, Japan) were inoculated and incubated for 1–2 days at 37°C in a microaerophilic atmosphere (6–12% O2

and 5–8% CO2; the remaining gases being mostly N2 from air). BHI broth check details (Difco) supplemented with 10% 17-DMAG (Alvespimycin) HCl FBS (Gibco, Carlsbad, CA, USA) was used as

a liquid medium (at 37°C in a microaerophilic atmosphere). Bacterial strains other than Campylobacter were also grown in BHI broth supplemented with 10% FBS (at 37°C). Prior to motion analysis, test bacteria were grown in BHI containing 10% FBS at 37°C for approximately 3 hrs (to a log phase). Bacterial motility was then examined under an inverted, phase-contrast microscope with a Micro Warm plate (Kitazato, Tokyo, Japan) that regulated the temperature of the specimens. The motility speed (μm/s) was measured using a motion analysis system with the program C-Imaging C-MEN (Complix); the limit of resolution of swimming speeds was 100 μm/s. Bacterial swimming in a liquid layer of BHI broth containing 10% FBS (106 to 107 colony forming units/mL) between a glass slide and a glass cover (pre-coated with FBS) was continuously recorded 15 times in 0.05 s analysis segments (a total of 0.75 s) and the swimming speed (μm/s) of each bacterial cell in a specimen obtained, essentially as described previously [15]. Pre-coating the glass surface with FBS is important because it prevents attachment of test bacteria to the glass surfaces. Measurements were performed in at least five different fields of each specimen, swimming speeds for approximately 300 bacterial cells being measured for each specimen (within a few mins), and the percentage of motile bacteria determined.

However, McCarron et al [26] did not comment as to whether those

However, McCarron et al. [26] did not comment as to whether those haemorrhagic cases with Selleck Kinase Inhibitor Library APOE ε2 allele also displayed capillary CAA, although this might be worth further investigation. In the present study, the severity of cortical SP was found to be independent of APOE ε4 allele frequency. Previous studies have reported conflicting results. Rebeck et al. [27] reported a greater frequency of SP in APOE ε4 allele homozygotes compared with non-ε4 carriers. However, Greenberg et al. [19] found no difference in SP density in APOE ε4 allele heterozygotes compared with homozygotes, but

did find fewer SP in non-ε4 allele bearers. Attems et al. [16] noted only a weak correlation between SP density and possession of APOE ε4 allele. However, others [11, 15, 21] noted that Aβ plaque count was not associated with possession of APOE ε4 allele. These apparent discrepancies may be explained by a consideration of the actual Aβ peptide species within SP. We have noted that plaque levels of Aβx-42 in AD did not vary according to APOE ε4 allele, but those of Aβx-40 increased in line with APOE ε4 allele copy number [28]. As all morphological forms of SP (that is, both cored

and diffuse) contain Aβx-42, whereas KPT-330 order Aβx-40 is present largely, or only, in cored plaques, antibodies, such as 4G8, which are not end-specific to Aβx-40 or Aβx-42, will therefore detect all morphological forms of SP and thus overall ‘counts’ will essentially reflect the numbers/density of Aβx-42-containing SP. The relationship

between Aβ plaque density and CAA appears less clear. Although the present study did not specifically address any possible correlation between the two pathological entities, it was noted that the severity of Aβ plaque deposition did not significantly differ across the four separate phenotypes. Despite this, both Tian et al. [29] and Chalmers et al. [15] reported a negative association between Aβ plaques and CAA severity, whereas others Farnesyltransferase have suggested that Braak stage (NFT density) is a better correlate with CAA than is SP density [16]. Because of potentially increased risks of associated cerebral haemorrhage or infarction, it is important to be able identify ways of diagnosing CAA during life, particularly the more extensively and severely affected cases. Knowing the APOE genotype may contribute to being able to more accurately predict the type of CAA present, and therefore associated risk. Nonetheless, as shown here, the heterogeneity in pathology with regards to CAA fails to be explained by APOE genotype alone. As findings from Genome Wide Association Studies (GWAS) increase [30, 31], it is possible that risky variants with certain AD susceptibility loci might be identified which selectively promote one type of pathological phenotype over another.

This contributes to disease pathology, in part via positive feedb

This contributes to disease pathology, in part via positive feedback loops between T and myeloid cells [49, 50]. The percentage of CD4+ cells expressing the

activation marker CD69 was elevated compared with that in WT in lyn–/–, but not lyn–/–IL-21–/– mice (Fig. 6C and Supporting Information Fig. 4). However, the frequency of IFN-γ, IL-4, and IL-17-producing cells among CD4+ T cells was similar in aged lyn–/– and lyn–/–IL-21–/– mice (Fig. 8D, Supporting Information Fig. 4). In the myeloid compartment, we observed an elevated frequency of CD11b+ cells in both lyn–/– and lyn–/–IL-21–/– spleens (Fig. 7). This increase was primarily in the CD11b+Gr1+CD11c− subset (Fig. 7). Because of variability in the total number of splenocytes in aged lyn–/– and lyn–/–IL-21–/– mice (Supporting Information Fig. 5), it was difficult to detect significant changes in the total number of T and myeloid cell subpopulations. Fostamatinib in vitro However, since the relative frequency of myeloid cells is increased significantly in both lyn–/– and lyn–/–IL-21–/– mice, other cell types will have greater exposure to them and the factors they produce than in WT mice. Finally, we asked whether IL-21 mediates kidney damage in lyn–/– mice. Despite the lack of anti-DNA IgG, aged lyn–/–IL-21–/– mice experienced severe GN (Fig. 8A and B). They also demonstrated an increased frequency of CD11b+ (both CD11c−/lo and CD11c+ subsets) and CD8+ cells in the

kidneys (Fig. 8C find more and Supporting Information Fig. 6). Each of these populations has been shown to be elevated in the nephritic kidneys of other lupus models [51, 52]. IgG deposits were observed in four of four lyn–/–IL-21–/– kidneys examined (Fig. 8B and Supporting Information Fig. 6), likely due to residual autoreactive IgG against non-DNA Ags (Fig. 5). Tubular interstitial nephritis was minimal, although mildly elevated (Supporting Information Fig. 6). These results are consistent with a predominant role for immune complex-mediated

kidney damage. IL-21 is associated with lupus in both humans and mice [18, 29-36]. While IL-21 mRNA is not significantly elevated in Lyn-deficient mice, several manipulations that reduce autoantibodies also dampen IL-21 expression. This suggested a role for IL-21 in the autoimmune phenotype of lyn–/– mice. Indeed, we show that IL-21 is required for IgG against Rebamipide DNA and some other, but not all, self-Ags in lyn–/– mice. However, IL-21 is dispensable for kidney damage in these animals. IL-21 could promote autoreactive B-cell class switching in two ways; by directly acting on B cells [18, 19, 21, 25-28], and/or by maintaining ICOS+CXCR5− and ICOS+CXCR5+ CD4+ T cells. These subsets are efficient B-cell helpers in extrafollicular and GC responses, respectively [29, 30]. Autoreactive B cells are likely activated in an extrafollicular response in lyn–/– mice. These animals fail to form GCs, either spontaneously or in response to immunization [4, 47, 48].