Deltamethrin has been previously

reported for its immunotoxic effects and therefore its exposure DAPT may affect the host resistance to infection and tumour challenge. Effect of exposure of deltamethrin on host resistance to Candida albicans infection was examined in Swiss albino mice. The objective of this study was to investigate the modulatory action of deltamethrin in C. albicans infected mice. The dose of deltamethrin was initially tested and selected from our previous study (18 mg/kg). Percentage of infection in deltamethrin treated animals increased faster when compared to that of the controls. Deltamethrin exposure along with C. albicans infection caused alteration of humoral immune response. The number of colony forming unit in liver and spleen were also found to be significantly increased in the treated EPZ-6438 nmr group. The results from our present study suggest that deltamethrin exhibits an immunosuppressive effect and has

a negative impact on host resistance to C. albicans infection. Important negative effects of potentially harmful xenobiotics present in the environment and in food have been shown to be directed against the immune system, which in the long term could affect host susceptibility to infections and tumour challenge [1, 2]. A chemical substance could disturb the normal homeostasis of the immune system, resulting in enhanced pathogen invasion, growth and tissue damage, or in the event of immune-mediated toxicity, on the immune system itself, or on other organ systems. The immune system appears to be particularly sensitive to modulation by certain classes of environmental chemicals, including polycyclic aromatic hydrocarbons, halogenated aromatic hydrocarbons (such as TCDD), and non-essential trace elements (such as Pb, Cd, Hg and Ni) all of which are classified as common pollutants in the food and the environment [3]. However, it is important

to distinguish between small and biologically unimportant changes in immune parameters presumed PD184352 (CI-1040) to be without health consequences and those changes that may jeopardize host defense. In many studies an alteration in immune function has been observed in the absence of a demonstrable change in host resistance [4]. Moreover, infection-induced mortality resulting from western encephalitis virus was reduced when arsenic was administered before virus inoculation, whereas arsenic administered during ongoing infection increased mortality [5]. Thus, different experimental conditions in terms of animal strain and species, type and strain of micro-organism, as well as dose and route of administration and test substance regimen may greatly affect outcome of an infection.

Presence of tumor-associated macrophages (TAMs) in malignant click here tissue correlates frequently with worse disease

prognosis and higher propensity of metastasis [1-3]. Schematically, macrophages can be divided into two categories, representing two extreme phenotypes: inflammatory M1 and anti-inflammatory M2 macrophages. Other than the classical M1 macrophages endowed with antimicrobial and immune-stimulatory properties, the M2-skewed TAMs [1] dampen tumor-directed T-cell responses [4], stimulate angiogenesis [5-7], support tumor growth by cytokine supply [5, 8], and promote dissemination of malignant cells [1]. Despite our increasing knowledge of functional aspects of the tumor–TAM interplay, the ontogeny of tumor-resident macrophages is less well-understood. Macrophages in nonmalignant tissues can be of a dual, monocyte-dependent and/or monocyte-independent origin [9]. In the former case, blood monocytes extravasate to steady-state or inflamed tissues, where they terminally differentiate and replace aged or exploited macrophages.

This model proves its merit in case of acute inflammatory processes, in which a high demand for tissue macrophages exists due to their extensive turnover, but it fails to explain many phenomena observed under homeostasis or during chronic inflammation [10]. For instance, a plethora of highly Gefitinib research buy specialized tissue-resident macrophages proliferate in situ under steady-state [11-15] and inflammatory conditions [16-19] and are able to self-maintain without significant input of marrow-derived precursors. TAMs settle inflammatory and dynamically expanding tumor environments with an elevated demand for macrophages supporting growth of the neoplasm. Circulating conventional monocytes (Gr-1+/ Ly6C+), either of BM or splenic origin, were shown to contribute markedly to the TAM pool [7,

20, 21]. On the other hand, recent reports on proliferating TAMs in human breast malignancies [3] indicate that TAMs may possess the capability to self-maintain independently of blood-borne precursors. An important aspect of TAM biology is how the malignant milieu influences differentiation of macrophages for tumor’s own sake. Urease In this respect, the potent hematopoietic cytokine CSF1 was proposed to be one of the main players [6, 8, 22]. The ubiquitously expressed CSF1 was proven to foster the development of various populations of tissue-resident macrophages and the complete maturation of blood monocytes [12]. In mammary cancer, CSF1 produced by tumor cells was shown to drive accumulation of TAMs that supply the neoplasm with the crucial growth factor EGF [8]. Studies on human breast carcinoma patients revealed a link between elevated expression of STAT1 and markers of macrophage infiltration with an impact on disease outcome [23].

The opinions expressed herein are those of the authors and should not be construed as the official policy of the NIH. Overlapping

WNV peptide arrays were obtained through the NIH Biodefense and Emerging Infections Research Resources Repository, NIAID, NIH. We thank Dr. Thomas Monath (Acambis, learn more Inc.), Dr. Alan Barrett (UTMB, Galveston) and Dr. Kristen Bernard (Wadsworth Center, Albany, NY, USA) for kindly providing JEV SA14-14-2, JEV Beijing and WNV 3356, respectively. We thank Dr. Michael Brehm for technical advice and Dr. George Reed and James Potts for assistance with statistical analysis. We also thank Dr. Alan Rothman, Dr. Anuja Mathew and Dr. Mary Co for helpful advice and comments with regard to experimental design and manuscript review. Conflict of interest: The authors have no financial or commercial conflict of interest. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-edited or typeset. They are made available

as submitted by the authors. “
“A diagnosis of idiopathic anaphylaxis following a detailed clinical assessment remains very challenging for patients and clinicians. Risk reduction strategies such as allergen avoidance are not possible. This study investigated Sirolimus whether the (ISAC) allergen array with 103 allergens would add diagnostic value in patients with idiopathic anaphylaxis. We extended the specific immunoglobulin (Ig)E testing in 110 patients with a diagnosis of idiopathic anaphylaxis from five UK specialist centres using ISAC arrays. These were divided into three groups: score I identified no new allergen sensitization beyond those known by previous assessment, score II identified new sensitizations which were not thought likely to explain the anaphylaxis and score III identified new sensitizations felt to have a high likelihood of being responsible for the anaphylaxis. A proportion (50%) of score III patients underwent clinical reassessment to substantiate the link to anaphylaxis in this group. The results show that 20% of the arrays were classified as score III with a high likelihood DOK2 of

identifying the cause of the anaphylaxis. A wide range of major allergens were identified, the most frequent being omega-5-gliadin and shrimp, together accounting for 45% of the previously unrecognized sensitizations. The ISAC array contributed to the diagnosis in 20% of patients with idiopathic anaphylaxis. It may offer additional information where a careful allergy history and follow-on testing have not revealed the cause of the anaphylaxis. “
“Pulmonary oedema is a hallmark of acute lung injury (ALI), consisting of various degrees of water and proteins. Physiologically, sodium enters through apical sodium channels (ENaC) and is extruded basolaterally by a sodium–potassium–adenosine–triphosphatase pump (Na+/K+-ATPase). Water follows to maintain iso-osmolar conditions and to keep alveoli dry.

Flow cytometry.  Neutrophil cell surface adhesion molecule expression was determined by flow cytometry. Isolated neutrophils (10 × 106/ml) were incubated in RPMI with anti-CD11b-AlexaFluor488 and anti-CD62L-PE or anti-CD11a-PE, for 30 min, 4 °C, protected from light. Subsequently, cells were washed with PBS and fixed with 1% paraformaldehyde until analysis. Cells were analysed at 488 nm on a FACScalibur (BD Biosciences, Heidelberg, Germany) and CellQuest Software was used for acquisition. Data were expressed as mean fluorescence intensities (MFI) and % of positive cells (% gated) compared to a negative isotype control. Real-time PCR.  Extraction of mRNA

check details and synthesis of cDNA: For extraction of neutrophil RNA, neutrophils (5 × 106 cells minimum) were pelleted at 4800 g for 20 min and RNA extracted using TRIzol, according to the manufacturer’s instructions (Invitrogen Corp., Carlsbad, CA, USA).

Complementary DNA (cDNA) was synthesized and verified as previously described [19]. Amplification and quantification of gene expression: Synthetic oligonucleotide primers were designed to amplify cDNA for conserved regions of the CD62L, alpha subunit of CD11a and alpha subunit of CD11b (PrimerExpress™; Applied Biosystems, Foster City, CA, USA). For primer selleck screening library sequences, see Table 1. Primers were synthesized by Invitrogen (São Paulo, Brazil) and ACTB and GAPDH were used as control genes. All samples were assayed in a 12 μl volume containing 5 ng cDNA, 6 μl SYBR Green Master Mix PCR (Applied Biosystems) and adhesion molecule gene primers as well as GAPDH and ACTB primers in 96-well reaction plate (StepOne Plus – Applied Biosystems). To confirm accuracy and reproducibility of real-time PCR, the intra-assay precision was calculated according Ribonucleotide reductase to the equation: E(−1/slope) [20]. The dissociation protocol was performed at the end of each run to check for non-specific amplification. Two replicas were run on the plate for each sample. Results were expressed as the arbitrary units (A.U.) of gene expression when compared with the

control genes. Measurement of serum sL-selectin, IL-8 and ENA-78.  Peripheral blood was collected in glass tubes without anti-coagulant and serum separated by centrifugation and stored frozen (−80 °C) until ELISA. Serum sL-selectin, ENA-78 and IL-8 were determined by high sensitivity ELISA (R&D Systems, Minneapolis, MN, USA and BD Biosciences, San Jose, CA, USA, respectively), according to the manufacturers’ instructions. Statistical analysis.  All data are expressed as means ± SEM. Differences between groups were evaluated by ANOVA followed by Bonferroni’s test or by the Kruskal–Wallis test followed by Dunns test, as appropriate, unless otherwise specified. A P-value of ≤0.05 was considered statistically significant.

Unstimulated cells incubated with the DMSO control had a basal level of calcium, which increased upon 10 μg/mL anti-IgM incubation

(Fig. 6K). However, B cells in the presence of 10 mM dimedone did not increase intracellular calcium levels following BCR crosslinking. To determine the specific steps during store-operated calcium influx that require reversible cysteine sulfenic formation, we measured ER calcium release by incubating B cells in PBS supplemented with 1 mM EGTA. ER calcium release was initiated when B cells were incubated with 10 mM dimedone, but not the DMSO control, in the absence of stimulation (Fig. 6L). However, when extracellular calcium was added to the cells, CCE was slightly decreased in the dimedone samples compared with the control thapsigargin treatment. To directly assess whether CCE requires reversible cysteine sulfenic acid formation, B Sirolimus research buy cells were stimulated with thapsigargin in calcium-free buffer and then supplemented with CaCl2 containing DMSO control or dimedone.

Thapsigargin treatment initiated similar levels of ER calcium release in both samples. However, compared with the DMSO control, cells in the presence of CaCl2 and dimedone did not exhibit an increase MK-8669 in CCE (Fig. 6M). Interestingly, NAC treatment had similar effects on ER calcium release and CCE in B cells (Supporting Information Fig. 3A and B). Taken together, these results indicate that ROIs and the reversible cysteine sulfenic Montelukast Sodium acid formation regulate sustained tyrosine phosphorylation, ER calcium release, and CCE mobilization in B cells. In this study, we examined the role of reversible cysteine sulfenic acid formation during B-cell activation and proliferation. Here we report six novel observations. First, compared with antibody-mediated BCR ligation, we demonstrate cognate antigen stimulation elicits similar kinetics of ROI production. Second, the ROIs generated during BCR ligation are associated with increased sulfenic acid levels in the total proteome. Third, the global increase in cysteine sulfenic acid following B-cell activation is localized to both the

cytosol and nucleus. Fourth, SHP-1, SHP-2, and PTEN are modified to cysteine sulfenic acid following BCR ligation. Fifth, B-cell proliferation requires reversible cysteine sulfenic acid formation. Sixth, both ER calcium release and CCE require reversible cysteine sulfenic acid formation. Taken together, these results demonstrate that ROIs generated during BCR ligation function as secondary messengers by oxidizing cysteine residues in signaling proteins that promote activation and proliferation. The observations made here and elsewhere strongly support ROIs and reversible cysteine sulfenic acid as positive regulators of BCR signaling. First, a prior study by Capasso et al. [8] has shown that ROIs are necessary for maintaining oxidized SHP-1 to facilitate proper BCR signaling.

Bound anti-IL-15 was visualized

by anti-rabbit antibody (Invitrogen). Antibodies were labeled with Alexa Fluor 488, Alexa Fluor 647, FITC, or allophycocyanin. BM was analyzed on a Quorum Spinning Disk Confocal Microscope, equipped with an ASI motorized XY stage. Data were analyzed using Volocity software (http://www.perkinelmer.ca/en-ca/pages/020/cellularimaging/products/volocitydemo.xhtml), FK228 in vitro which allowed individual pictures to be linked together to reconstruct the entire femur. Then, after identifying red fluorescent T cells at low magnification, the direct contacts of each transferred memory T cells were enumerated for each set of stains. Where indicated, for comparison of two groups, p-values were obtained using the Student’s t-test (unpaired, two-tailed, 95% confidence interval). One-way ANOVA was used to compare multiple groups, and statistical significant differences with p < 0.05, p < 0.01, and p < 0.001 were indicated as *, **, and ***, respectively. We thank Byoung Kwon, National Cancer Center, Korea, for 4–1BB−/– mice; Robert Mittler, Emory University, for provision of the 3H3 anti-4–1BB and 19H3 anti-4–1BBL hybridomas, Hideo Yagita of Juntendo University for provision of the TKS-1 hybridoma; Peter Doherty and Paul Thomas, St. Jude

Children’s Research Hospital, for providing influenza A/HKx31-OVA; the National Institute of Allergy and Infectious Disease tetramer facility for MHC I tetramers, and Birinder Ghumman and Thanuja Proteasome inhibitor Ambagala for technical assistance. This research was funded by grant number MOP 84419 from the Canadian Institutes

of Health Research (CIHR) to T.H.W. T.H.W. holds the Sanofi Pasteur chair in Human Immunology at the University of Toronto; G.H.Y.L. was funded by a CIHR doctoral award. F.E. was funded by Amylase a research fellowship of the German Research Foundation (DFG). A.E.H. was supported by research grant HA5354/4–1 from the German Research Foundation (DFG). The authors declare no financial or commercial conflict of interest. Disclaimer: Supplementary materials have been peer-reviewed but not copyedited. Figure S1. Defective CD8 T cell recall response to influenza virus in the absence of 4–1BB in mice. Figure S2. Gating used for analysis of CD8 T cell response after influenza infection. Figure S3. 4–1BBL+ cells are enriched in the BM CD11c+ MHC-IIneg fraction. Figure S4. Analysis of chimerism following the generation of radiation bone marrow chimeras. Figure S5. Gr1+ and B220+ do not overlay and therefore are not pDC. Figure S6. 4–1BBL is expressed on Gr1lo cells and not B cells in the bone marrow of unimmunized mice. “
“Estradiol regulates chemokine secretion from uterine epithelial cells, but little is known about estradiol regulation in vivo or the role of estrogen receptors (ERs).

Prion biomarkers are altered in the cerebrospinal fluid (CSF) of CJD patients, but the pathogenic mechanisms selleck chemical underlying these alterations are still unknown. The present study

examined prion biomarker levels in the brain and CSF of sporadic CJD (sCJD) cases and their correlation with neuropathological lesion profiles. The expression levels of 14-3-3, Tau, phospho-Tau and α-synuclein were measured in the CSF and brain of sCJD cases in a subtype- and region-specific manner. In addition, the activity of prion biomarker kinases, the expression levels of CJD hallmarks and the most frequent neuropathological sCJD findings were analysed. Prion biomarkers levels were increased in the CSF of sCJD patients; however, correlations between mRNA, total protein and their phosphorylated forms in brain were different. The observed downregulation of the main Tau kinase, GSK3, in sCJD brain samples may

help to explain the differential phospho-Tau/Tau ratios between sCJD and other dementias in the CSF. Importantly, CSF biomarkers GSK458 levels do not necessarily correlate with sCJD neuropathological findings. Present findings indicate that prion biomarkers levels in sCJD tissues and their release into the CSF are differentially regulated following specific modulated responses, and suggest a functional role for these proteins in sCJD pathogenesis. Astemizole “
“This chapter contains sections titled: Introduction Specimen Preparation: Special Considerations Collection and Preservation Trimming and Processing Special Stains and Techniques Neuroanatomy References “
“This chapter contains sections titled: Introduction Necropsy Trimming and Embedding Staining Evaluation “
“Edited by Brad Bolon and Mark Butt Fundamental Neuropathology for Pathologists and Toxicologists: Principles and Techniques . John Wiley & Sons, Inc. , Hoboken, NJ, USA , 2011 . 590 Pages. Price £100.00 (hardback). ISBN 978-0-470-22733-6 Each

book has its own particular flavour that reflects the input from editors and authors and the subject of the book. Some are dry and impersonal whereas others are tasteful and even exotic. This book, edited by Brad Bolon and Mark Butt, has the flavour of home cooking and an intimate feel of a family whose members know each other very well and recognize the needs of all members of the family. The stated goal of the book is to provide a complete reference on the design and interpretation of studies involving toxicological neuropathology. It is aimed at pathologists, toxicologists and other scientists involved in the investigation of neurotoxicology. Right at the start of the book it is recognized that the nervous system is so complex that it requires more than a lifetime to understand; this complexity and the involvement of successive generations are central themes of the book.

This activity of IRF4-binding

protein stems from its ability to directly interact with IRF4 and prevent ROCK2-mediated IRF4 phosphorylation, thereby restraining IRF4 from binding the regulatory regions of Il17 and Il21 [49, 50]. IRF4 fulfills its central function in Th17-cell differentiation by interacting with BATF–JUN heterodimers to bind to AICEs. Notably, AICE motifs are located in regulatory elements of several genes that are important for Th17-cell differentiation, such as Il17, Il21, Il23r, and the lineage-specific transcription factor Rorc [14-17]. IRF4-mediated Th17 differentiation includes cooperation with the transcription factor STAT3 [28] and is specified by the lineage-specific transcription factor ROR-γt [17], which has been shown to physically interact with IRF4 [20]

(Fig. 1A). In agreement with this central cooperation MK-1775 solubility dmso of IRF4 and BATF during Th17-cell development, defective Th17-cell differentiation has also been reported in Batf–/– mice [51]. In addition to its T-cell intrinsic functions during Th17-cell differentiation, IRF4 might also control this process through its T-cell extrinsic roles, including its central role in the development of IL-6-producing CD11b DCs [8, 9]. Tfh cells are characterized by the expression of the CXC chemokine receptor 5 (CXCR5), of inducible costimulator (ICOS), and of programmed death-1 (PD-1) [33]. IRF4 deficiency has been shown to find more cause diminished differentiation of CXCR5+ICOS+CD4+

Tfh cells after immunization of mice with keyhole limpet hemocyanin (KLH) [52]. Similarly, infection of Irf4–/– mice with Leishmania major led to a failure to generate CXCR5+ICOShiCD4+ Tfh cells and to form GCs [53]. Moreover, Irf4–/–CD4+ T cells isolated from draining LNs of infected mice were shown to express lower levels of BCL-6 than WT CD4+ T cells, suggesting that IRF4 regulates Tfh-cell generation in a BCL-6-dependent manner (Fig. 1A). As IRF4 directly targets and activates BCL-6 expression in B cells [54], it is probable that this is also the case pentoxifylline in Tfh cells. The lack of Tfh-cell differentiation in Irf4–/– mice was attributed to both T-cell intrinsic and extrinsic B-cell defects [53, 54]. IL-21 is a key cytokine for Tfh-cell development [33], and IRF4 has been shown to regulate the production and responsiveness to IL-21 [49, 52, 55]. Therefore, alteration of IL-21 expression and signaling probably contribute to the control of Tfh-cell differentiation and GC formation by IRF4. During IL-21 signaling, IRF4 functionally cooperates with the IL-21-induced transcription factors STAT3, to control most IL-21-regulated genes [52].

However, it is not clear whether or to what extent the γδ TCR is involved in this process. In this study, we investigated the functionality of γδ and αβ TCR expressed on freshly isolated systemic T lymphocytes and

iIEL by measuring the increase of intracellular free calcium concentration ([Ca2+]i) levels after TCR stimulation on a single cell basis. Of note, we found that γδ and αβ iIEL had high levels of basal [Ca2+]i. Furthermore, we detected elevated basal [Ca2+]i levels in CD8αα+ when compared with [Ca2+]i in CD8αα− γδ (DN) iIEL. These elevated basal [Ca2+]i levels correlated with lower responsiveness to TCR-specific stimulation. Furthermore, we were able to tune down basal [Ca2+]i levels of γδ CD8αα+ iIEL in vivo through the systemic administration of specific anti-γδ TCR mAb. Irrespective of the mechanism, this effect implied that diminished TCR signaling selleckchem capacity resulted in lower basal [Ca2+]i levels

and thus provided evidence that the γδ TCR was indeed functional and likely to be constantly triggered in vivo. Additional, albeit indirect support for a functional TCR in iIEL was offered by ex vivo stimulation assays demonstrating that TCR ligation of some γδ and αβ iIEL populations led to more effective chemokine and cytokine production compared with unspecific stimulation with PMA/ionomycin. Taken together, we describe here the short-term (seconds) and medium-term (hours) outcome of TCR-stimulation of various iIEL populations. We conclude that their TCR, at least in γδ iIEL, must be functional in vivo. Monitoring of [Ca2+]i increase in the cytoplasm of T cells after TCR ligation is an established experimental system Selleckchem Opaganib to quantify TCR responsiveness on a single-cell basis 31, 32. For γδ T cells, this was so far difficult, because the DCLK1 identification of bona fide γδ T cells depended on staining with mAb directed against the γδ TCR. In order to directly measure

intracellular Ca2+ levels of γδ T cells in response to stimulation of their TCR, we thus made use of TcrdH2BeGFP (Tcrd, T-cell receptor δ locus; H2B, histone 2B) reporter mice 33. More precisely, we used F1 C57BL/6-Tcra−/−×TcrdH2BeGFP double heterozygous mice (γδ reporter mice) in which expression of the reporter H2BeGFP unambiguously identifies γδ T cells without touching their TCR. This system was chosen to avoid any false-positive GFP+ cells that could be found in the homozygous TcrdH2BeGFP reporter mice due to mono-allelic rearrangements of the Tcra/Tcrd locus. By co-staining with anti-CD8α, five populations of either systemic T cells or iIEL were defined (Fig. 1A). In the systemic T-cell compartment, CD8α expression identified αβCD8+ T cells (CD8+ p-αβ) while GFP expression identified γδDN T cells (CD8− p-γδ). In iIEL preparations, GFP+ γδ T cells were divided into CD8α− (CD8− i-γδ, approximately 20% of all γδ T cells, corresponding to γδDN iIEL) or CD8α+ (CD8+ i-γδ, approximately 80% of all γδ T cells, corresponding to γδCD8αα+ iIEL).

5c, top panel; see Supplementary material, Table S3). Although five Vκ segments were represented among 15 clones sequenced from B220lo CD19+ B cells, the 19–32 Vκ segment was highly over-represented among these clones, selleck being identified in 9/15 clones (60%) sequenced (Fig. 5c, top panel). Notably, 13/15 (87%) of these clones show a germ-line configuration, suggesting that the B220lo CD19+

B cells have not undergone somatic hypermutation in the germinal centre (Fig. 5c, lower right panel; see Supplementary material, Table S3). By contrast, the frequency of unmutated clones derived from B220hi CD19+ B cells is much lower, both in normal mice (5/13 clones; 38%) and dnRAG1 mice (19/38 clones; 50%). Accumulating B220lo CD19+ B cells resemble B1a B cells that are thought to be responsible for the production Dasatinib research buy of natural antibodies, so we wondered whether dnRAG1 mice might exhibit elevated levels of serum immunoglobulin. Surprisingly, however, measurements of serum IgM and IgG levels from unimmunized normal and dnRAG1 mice revealed that dnRAG1 mice have significantly lower levels (approximately threefold) of serum IgM and IgG than their WT counterparts (Fig. 6a).

To determine whether this outcome might be the result of defects in B-cell responsiveness toward antigenic stimulation, we measured the activation of WT or dnRAG1 splenocytes or sorted B220lo CD19+ B cells and B220hi CD19+ B cells using an MTT assay after mitogen treatment with lipopolysaccharide or BCR cross-linking using anti-IgM F(ab’)2 antibody. Metalloexopeptidase We found that both treatments stimulate splenocytes isolated from WT and dnRAG1 mice more than media alone, but dnRAG1 splenocytes showed a significantly diminished responsiveness toward stimulation by lipopolysaccharide or anti-IgM cross-linking than those isolated from WT mice (Fig. 6b, upper panel). Indeed, the level

of stimulation of dnRAG1 splenocytes by anti-IgM was not significantly different than a control F(ab’)2 antibody. Similar experiments conducted with sorted B220lo and B220hi B cells from WT and dnRAG1 mice revealed that while the B220hi and B220lo subsets are both stimulated by lipopolysaccharide, the level of stimulation is not significantly different between the subsets (Fig. 6b, lower panel). In contrast, B220hi B cells from WT mice responded significantly better to anti-IgM treatment than both B220hi and B220lo cells from dnRAG1 mice, with the difference being slightly greater for B220lo B cells (which showed no significant difference relative to treatment with a control F(ab’)2 antibody). The difference between WT and dnRAG1 B220hi B-cell responses is somewhat surprising, but it is likely that there is some heterogeneity in B220 expression levels among cells that are poorly responsive toward antigenic stimulation.