Histological assessment of the kidneys of these mice shows severe tubulointerstitial inflammation, with marked infiltration by T and B lymphocytes and macrophages (Fig. 3).23 CD4+ and CD8+ cell numbers increase in cortex and medulla of Adriamycin-affected kidneys, but not in spleen, suggesting

a direct role of these MK0683 manufacturer cells in modulating renal injury. However, studies in severe combined immunodeficient (SCID) mice (inbred BALB/c mice that lack lymphocytes) have demonstrated that structural and functional injury induced by Adriamycin does not require lymphocytes but can be modulated by the presence or absence of specific subpopulations. Renal injury develops in mice with doses of Adriamycin approximately half (5.3 mg/kg) that of wild-type BALB/c mice (9.8–10.4 mg/kg), suggesting that while lymphocytes are not essential, it is likely that a subpopulation of these cells protects against the development of renal injury. Further evidence for this comes from adoptive transfer studies of FoxP3 expressing CD4+CD25+ T cells, which protect against renal injury in AN,24 consistent with the exacerbation of renal injury by depletion of CD4+ T cells.25 selleck chemical The pattern of renal injury in SCID mice is similar to that in wild-type BALB/c mice. Macrophage infiltration is prominent in the tubulointerstitium but not in glomeruli (Fig. 4). Depletion

and reconstitution studies suggest a pivotal role of pro- and anti-inflammatory macrophages in the pathogenesis of Adriamycin-induced kidney injury.26–28 Adriamycin induces renal injury in the fetus as well as the mother. When Adriamycin is administered intraperitoneally 4 weeks prior to pregnancy, kidneys from the fetus show increased amounts of PAS-positive mesangial matrix, glomerulosclerosis, tubular injury and dilatation.29 Pregnant rats given Adriamycin 2 weeks prior

to pregnancy develop more severe proteinuria and higher blood pressure compared with non-pregnant rats, in association with an elevated ratio of thromboxane B2 (vasoconstrictor) to prostaglandin F1α (vasodilator) Casein kinase 1 synthesis, changes which normalize post-pregnancy in a manner analogous to human pre-eclampsia.30,31 In contrast, repeated pregnancies after the induction of AN are associated with persistent glomerular damage post-partum.32 Adriamycin administration early in gestation (days 7 to 9 of rat pregnancy), induces anomalies in urinary tract development, the most common being bilateral megaureters with hypoplastic bladder.33 We and others have examined the effect of various immunologic interventions in AN, which have enabled a greater understanding of the immune mechanisms underlying chronic proteinuric renal disease associated with tubulointerstitial fibrosis. Macrophages and lymphocytes are heterogeneous populations containing cells that act to promote or reduce inflammation and fibrosis (see review by Lee et al.34).

We show that resident γδ

T cells are an early, innate-like source of IL-17 and that γδ T cells amplify Th17 responses and exacerbate colitis development. Moreover, we also demonstrate that Foxp3+ TREG cells also suppress the expansion and cytokine-producing potential of resident γδ T cells at an early stage of colitis development. These findings will increase our understanding of TREG cell-mediated control of bacterially driven mucosal inflammation and may enable us to design novel approaches to potentiate TREG-cell function and consequential tolerance induction in various chronic inflammatory disorders. WT, TCR-β−/− and RAG2−/− B6 selleckchem mice were obtained from Taconic Laboratories, while GFP transgenic B6 (pUbi-GFPtg) mice were provided by Dr. Schaefer 56. All mice were generally used at 6–10 wk of age. Mice were housed and bred under specific pathogen-free conditions according to institutional guidelines at McGill University (animal use protocol ♯4715). For in vivo adoptive transfer, CD4+CD25+

(TREG), CD4+CD25− (TEFF), CD4+ (total) and γδ TCR+ T-cell subsets from appropriate mice were purified from a pool of splenocytes and LN cells using the autoMACS cell sorter (Miltenyi Biotec) according to the manufacturer’s protocol. Briefly, CD4+CD25+ T-cell fraction (∼90% purity) was obtained by positive selection for CD25. The remaining cells were used to obtain CD4+CD25− TEFF fraction (>93% purity) by positive selection for CD4. CD4+ and γδ TCR+ T-cell subsets (>93 and > 90% purity, respectively) Roxadustat price were obtained by positive selection for CD4 or γδ TCR. For in vitro suppression assays, T-cell subsets were isolated using a FACSAria™ Cell

Sorter with a purity > 98%. CD4+CD25− TEFF or CD4+CD25+ TREG cells were sorted from WT B6. CD3+γδ TCR+ T cells were sorted form TCR-β−/− mice. MACS purified CD4+CD25− TEFF (1.3×106), a mixture of CD4+CD25+ TREG (0.2×106) and CD4+CD25− TEFF Mirabegron (1.3×106) T cells, and (0.7×106) γδ T cells from GFP-Tg or WT donor mice were intravenously transferred into TCR-β−/− or RAG2−/− recipient mice. Individual body weight, as an indicator of disease incidence, was monitored and compared with body weight at the start point. Colonic tissues were collected from recipient mice and either directly mounted in optimum cutting temperature compound or fixed in 10% paraformaldehyde followed by paraffin embedding. Sections of 10 μm for frozen and 6 μm for paraffin embedded tissues were made, subjected to hematoxylin/eosin staining and analyzed by a pathologist giving the score from 0–4 based on previously described criteria 57, 58. In order to isolate lymphocytes from LP, a modified protocol from 59 was used. Briefly, colonic tissues from recipient mice were isolated, washed with PBS and cut into pieces.

The hypercalcemia is mediated

by extra-renal 1-alpha hydroxylation and is seen in other fungal infections in immunosuppressed patients. We suggest that PJP should be considered as a differential cause in unexplained PTH-independent hypercalcemia in renal transplant recipients even in the absence of respiratory symptoms. 288 INFECTIVE BURSITIS DUE TO MYCOPLASMA HOMINIS IN A SIMULTANEOUS PANCREAS KIDNEY TRANSPLANT RECIPIENT RS ELKHATIM1, CA MILTON1,3, DL GORDON2,3, JA BARBARA1,3, JY LI1,3 Department of 1Renal Medicine; 2Infectious Disease, Flinders Medical PF-6463922 Centre and 3School of Medicine, Flinders University, Adelaide, South Australia, Australia Background: Mycoplasma hominis is a common inhabitant of the genitourinary tract and recognized as an opportunistic pathogen. We report a case MAPK Inhibitor Library solubility dmso of infective bursitis due to M. hominis in a simultaneous pancreas kidney (SPK) transplant recipient. Case Report: A 39-year-old man with end stage renal failure secondary to diabetic nephropathy received SPK transplantation in November 2013. His post-transplant course was complicated by pancreatic graft loss due to arterial thrombosis.

Renal function has been stable (creatinine 76 μmol/L). Immunosuppressive therapy included tacrolimus, mycophenolate and prednisolone. Three weeks post-transplant, he developed a low grade fever, severe left hip pain and was unable to weight bear. The MRI showed an effusion in the trochanteric bursa with high T2 signal and oedema in the left gluteus and adductor muscles. The bursal fluid was aspirated and the culture grew M.

hominis. Muscle biopsy revealed no abnormality. He was treated with doxycycline which is planned for 6 months. He mobilized independently 4 weeks after treatment commenced. Conclusion: To the best of our knowledge, this is the first reported case of M. hominis causing bursitis in a transplant recipient. The combination of surgical manipulation of the urinary tract and immunosuppression places the renal transplant patient at high risk for Methamphetamine M. hominis infection. M. hominis lacks a cell wall, is not visualized on Gram stain and slow to grow in culture. Therefore, there is often a significant delay in diagnosis. It is important for clinicians to have high index of suspicion for atypical organisms whilst working up the cause of infection in immunosuppressed patients. The first choice antibiotic for M hominis is a tetracycline but the duration of therapy is not well established. 289 UNEXPLAINED NEPHROTIC-RANGE PROTEINURIA IN A CONSANGUINEOUS 2-YEAR-OLD BOY K BLAZE, T FORBES, C QUINLAN, A WALKER Royal Children’s Hospital, Melbourne, Victoria, Australia Background: We report a case of a consanguineous 26-month-old boy with a chromosome 2q35 deletion.

This is mainly due to the fact that the binding of GST containing fusion proteins on glutathione-Sepharose column is dependent on the proper folding of the GST tag. However, binding of proteins with the 6× His tag to Ni-NTA

agarose is not affected by the conformation of the expressed proteins and, consequently, proteins containing this tag can be purified even under denaturing conditions [36]. The use of pGES-TH-1 vector provides the advantage of high-level expression by having GST as fusion protein and the use of two tags (GST at the amino terminus and His tag at the carboxy terminus of the desired protein) for efficient purification [24]. In this study, high-level expression of Rv3874, Rv3875 and Rv3619c fusion proteins was achieved using this expression vector. Furthermore, Rv3619c could be purified by using only one affinity matrix (glutathione-Sepharose), AZD9291 molecular weight Ku-0059436 as reported for some other

mycobacterial proteins [15, 20], but the purification of GST-free pure Rv3874 and Rv3875 required two affinity matrices, glutathione-Sepharose and Ni-NTA agarose. These results further strengthen the suggestion that pGES-TH-1 is useful for high-level expression and efficient purification of recombinant mycobacterial proteins [24]. The reason for Rv3619c requiring only one column (glutathione-Sepharose) for purification could be the presence of the fusion protein GST-Rv3619c in the pellet of induced E. coli cultures, which Avelestat (AZD9668) lacked the contaminating E. coli protein of 70 kDa;

whereas GST-Rv3874 and GST-Rv3875 proteins were present in the soluble fraction that also contained E. coli protein of 70 kDa, which was capable of binding to glutathione-Sepharose column nonspecifically, and was eluted from the column along with Rv3874 and Rv3875. However, the subsequent use of Ni-NTA matrix efficiently removed the contaminating E. coli protein and made the recombinant Rv3874 and Rv3875 proteins homogeneously pure. The immunogenicity of all the three pure recombinant proteins was evaluated in antibody assays by immunizing rabbits, and the anti-sera were tested with the full-length proteins, pools of synthetic peptides covering the sequence of each protein and their individual peptides. The specificity of the antibodies was confirmed by Western immunoblot analysis, which demonstrated that pre-immunized rabbits’ sera did not have antibodies to any of these proteins, and the sera from immunized rabbits had antibodies reactive with the immunizing proteins only. These results suggest that the rabbits used were not exposed to M. tuberculosis and the epitopes of a given protein recognized by antibodies were not cross-reactive with other proteins.

If the excessive anticoagulation occurs, an infusion of fresh-frozen plasma and packed red blood cells may be required to reverse the effects of the interaction. Although CYP2C9 is a minor pathway for voriconazole biotransformation, it significantly inhibits S-warfarin. The interaction between voriconazole and warfarin increases the INR by 41%, and the effects Y-27632 order can persist for approximately 1 week after voriconazole discontinuation.134 This interaction

occurs independently of the homozygous PM phenotype.134 There are no published data describing an interaction between posaconazole and warfarin. Interactions involving azoles and phenytoin.  Certain azoles can interact with phenytoin in a bidirectional manner, whereby the azole first inhibits the CYP-mediated

metabolism, and then phenytoin subsequently induces the CYP-mediated RO4929097 nmr metabolism of the azole. Data from healthy volunteers demonstrate that fluconazole significantly increased the AUC0–24 and Cmin of phenytoin.135 Although the study demonstrated that phenytoin did not affect fluconazole pharmacokinetics, in practice, induction will likely occur. That study used healthy volunteers and thus the dose and duration of phenytoin were minimised for ethical and safety reasons.135 The bidirectional nature of the azole–phenytoin interaction is best illustrated with voriconazole. Phenytoin 300 mg once daily co-administration with oral voriconazole 400 mg twice daily for 10 days produced increased steady-state phenytoin Cmax and AUCτ values by approximately 70% and 80% respectively.136 However, when multiple doses of phenytoin (300 mg once daily) were administered with voriconazole 200 mg twice daily for 2 weeks, steady-state voriconazole plasma Cmax and systemic AUCτ were significantly reduced to approximately 50% and 30%, respectively, for up to 12 h postdose.136 Although doubling the voriconazole dose from 200 to 400 mg twice daily compensates for the effect of phenytoin,

it subsequently leads to the inhibition of CYP-mediated metabolism of Aldol condensation phenytoin,136 One parallel-designed interaction study demonstrated that posaconazole co-administration produced modest increases in steady state phenytoin Cmax (24%) and systemic AUC (25%), which were not considered clinically significantly.137 However, this study used healthy volunteers, included a small sample size, the volunteers did not serve as their own controls, and substandard doses of posaconazole (200 mg day−1) and phenytoin (200 mg day−1) were employed. Whether these limitations impacted the magnitude of the observed interaction remains unclear. Transport proteins are important contributors to drug disposition. Itraconazole, posaconazole and caspofungin are substrates and/or inhibitors of several transport proteins including P-gp and the OATPs.

Further, Teffs from T1D patients were suppressed to a greater extent by Tregs from the healthy control than by their own Tregs. Taken together, these findings suggest that the reduced regulation observed in autologous co-cultures of cells isolated from T1D patients was due to reduced Treg-mediated suppression intrinsic to the Treg population. Our results are in contrast with previous findings, showing that

responder T cells from T1D were more resistant to suppression [25, 26]. This could be explained by differences in the definition of cellular phenotypes and expansion conditions. While Schneider et al. used adaptive Tregs generated in vitro from CD4+CD25– cells [25], the Tregs used by us in this study were expanded from the

CD4+CD25hiCD127lo DAPT population. In the study by Lawson et al., sorted CD4+CD25hi cells without in-vitro expansion from patients with long-standing T1D were used, and Selleck MAPK inhibitor CD127 was not included to discriminate Tregs [26]. Although we have identified a deficient Treg-mediated suppression of polyclonal T cell stimulation in T1D patients who participated in the GAD-alum Phase II trial, treatment with GAD-alum did not affect the suppressive activity of Tregs. It should be kept in mind that samples included in the current study were drawn 4 years after treatment, and that an effect on suppression shortly after treatment cannot be excluded. Furthermore, due to the random selection of patients based on the availability of samples, none of the GAD-alum-treated patients classified as responders to treatment were included in suppression assays [10], and we were thus unable to relate suppression to clinical outcome. Because our assay measures suppression of polyclonal activation, an effect on the specific suppression in response to GAD65 stimulation cannot be excluded. In fact, changes in the frequency of T cells with a Treg phenotype during the trial have been observed only upon GAD65 stimulation [9], while the frequency of Tregs after

culture in medium alone has been similar in GAD-alum and placebo-treated patients throughout the study. Proliferative responses of PBMC from GAD-alum-treated patients in response to GAD65 stimulation were significantly stronger compared Flavopiridol (Alvocidib) to placebo in a thymidine incorporation assay, as we have reported previously [12], suggesting that the GAD65-specific responses initiated by in-vitro antigen recall are not anergic. In conclusion, we demonstrate GAD65 recall-induced populations of CD4+CD25hiCD127lo Tregs as well as FSChiSSChiCD4+CD25+CD127+ activated T cells, detectable 4 years after treatment. A deficiency in Treg-mediated suppression detected in T1D patients was intrinsic to the Treg population, but was not affected by GAD-alum treatment.

1). This protein SB203580 synthesis-dependent STAT3 activation, which was reminiscent of findings previously made in the THP-1 monocytic cell line 27, coincided with suppression of the IL-10-induced transcriptional inhibition in monocytes and LPS-conditioned neutrophils, despite unchanged levels of surface IL-10R 26. These findings demonstrate that, at least

in human monocytes and LPS-conditioned neutrophils, de novo protein synthesis is necessary to allow prolonged activation of STAT3 by IL-10, which, in turn, is obligatory for triggering the AIR. It is therefore conceivable that in LPS-conditioned human neutrophils’ protein synthesis is necessary to achieve both the expression of newly made functional IL-10R and the manufacture of unidentified factor(s) that are needed to maintain prolonged STAT3 activation. Candidates for the unidentified factor(s) might include a labile inhibitor of (an) inducible factor(s) that, similarly to suppressor of cytokine signaling-3 (SOCS-3) in the IL-6/IL-6R system,

might negatively regulate STAT3 activation. Accordingly, IL-6 is unable to generate the AIR, despite its capacity to trigger potent, but transient, STAT3 activation 28, 29; however, if SOCS-3 is deleted by gene targeting, then IL-6-mediated STAT3 activation becomes more sustained and able to trigger an AIR indistinguishable Torin 1 mw from that induced by IL-10 30, 31. Clearly, the identification of the regulatory factors involved in the IL-10-signaling cascade, responsible for producing AIR, remains an urgent issue to be solved. In this context, it is interesting to note that a study aimed at identifying the functional relevance of different cytoplasmic domains of human and murine IL-10R1 characterized a stretch of 30 Mannose-binding protein-associated serine protease amino acids within the C-terminal region that seem to be necessary for the anti-inflammatory activities of IL-10 2. It is thus possible that a yet unidentified pathway, involving putative signaling component(s), departs from that specific IL-10R1 region and ultimately modulates cytokine expression in LPS-treated neutrophils incubated with IL-10. Whatever the situation turns out to be, several intracellular and

inducible candidates have already been suggested to mediate IL-10-dependent AIR, including B-cell lymphoma (Bcl)-3 32, heme oxygenase (HO)-1 33, A20-binding inhibitor of NF-κB activation (ABIN)-3 34, one member (IκBNS) of the IκB family of proteins 35, 36, ETV3 (a member of the ETS family of repressors of gene expression) and a transcriptional corepressor Strawberry notch homologue (SBNO)-2 37. In addition, SOCS-3 protein is inducible by IL-10 in human and murine phagocytes 38, 39 and overexpression studies have shown it to mimic IL-10-induced AIR 40. However, the generation of macrophage-specific SOCS3-null mice has excluded the involvement of SOCS3 in mediating the anti-inflammatory or immunoregulatory effects of IL-10 31, 41.

2b). The colons, in addition, had significantly higher levels of the cytokines Csf2, Csf3, Il9 and Tnfa. The observed chemokine and inflammatory gene expression pattern was clearly reflected in the composition of the inflammatory infiltrates in the caeca and colons of the C. difficile-infected mice. Both organs contained significantly higher numbers of neutrophils after the infection (Fig. 3a), a finding consistent with the significant up-regulation of Cxcl1, Cxcl2 and Il17f. In addition, there was a substantial increase in CD11b expression on the recruited neutrophils

(Fig. 3b). Flow cytometric analysis showed a significant increase in the number of dendritic cells and cells of the monocyte/macrophage lineage in the caeca of the C. difficile-infected mice (Fig. 4a,b; compare with Supplementary material, Figure S3A and B); which was consistent with the increased expression levels of Ccl2. The infected colons showed a similar GSI-IX molecular weight trend. A substantial fraction of the monocyte/macrophage lineage cells in the caeca and colons of the infected mice

expressed low levels of MHC II (Fig. 4c), which was consistent with their recent recruitment. The significant increase in the number BAY 80-6946 mouse of lymphocytes (B cells, CD4 T cells and CD8 T cells) in the caeca and colons of the C. difficile-infected mice (Fig. 5a; compare with Supplementary material, Figure S4A) also correlated with the heightened expression of chemokines and pro-inflammatory genes. Nonetheless, the recruited CD4 T cells expressed levels of CD69 that were comparable with that found in their untreated counterparts (Fig. 5b; compare with Figure S4B) and had low levels of CD25 expression (assessed on CD4 T cells with gating to exclude the FoxP3+ subset) (Fig. 5c; compare with Figure S4C). These observations were in full biological concordance with the lack of any significant change in Tbx21, Gata3 or Rorc expression levels or in that of cytokines secreted by polarized T cells (data not PRKACG shown). There was a significant up-regulation of Il22 expression and

a number of anti-microbial peptides in the caeca and colons of the infected mice. These included Defa1, Defa28, Defb1 and Slpi in the colon and Reg3g in the caecum (Fig. 2c). There was also an increase in Reg3g levels in the colons of infected mice; however, in these experiments, the increase did not reach statistical significance. To assess the activation of the UPR in C. difficile infection in mice, caecal and colonic samples from untreated and C. difficile-infected mice were examined for their expression of numerous UPR markers. Immunoblotting showed a significant increase in the level of eIF2α phosphorylation, the most rapid aspect of the UPR, in the caeca and colons of the infected mice (Fig. 6a). This coincided with the significant up-regulation of Gadd34 and Wars mRNA expression levels, both downstream of eIF2α phosphorylation, in the infected samples (Fig. 6b).

Although D/P Cr levels at 6 months after the therapy were significantly lower than those at the initiation of the therapy (0.68 ± 0.10 to 0.62 ± 0.10), D/P Cr levels at 18 months after the therapy were aggravated. Conclusion: It appears that the combination therapy with PD and HD improves Hb levels XL765 and cardiac function because of adjusting

body fluid status. It was indicated that the peritoneal function at 6 months after the therapy may be improved, but that at over 18 months after the therapy may be aggravated. Therefore, the combination therapy is useful for a lifestyle viewpoint of patients at the transitioned period of PD to HD with end-stage kidney disease. LAI XUELI, CHEN WEI, LI JUAN, BIAN XIAOLU, WANG HAIYAN, GUO ZHIYONG Department of Nephrology, Changhai Hospital

Introduction: It is known that sleep disturbance is associated with quality of life and all cause mortality in end stage renal disease population. However, limited researches focused on biomarkers of daytime sleepiness, especially excessive daytime sleepiness (EDS) in peritoneal dialysis (PD) patients. This study aims to explore the metabolic signatures of EDS cases in PD population. Methods: A cross-sectional study collected fast serum ATM inhibitor from no-diabetic continuous ambulatory peritoneal dialysis (CAPD) patients in a single centre from Feb 2013 to June 2013. A validated Chinese version of Epworth Sleepiness Scale (ESS), self-administered questionnaires for sleep quality evaluation was performed. EDS group was defined as ESS ≥ 9. Meanwhile the PD Kt/V, residual renal function (RRF) and peritoneal equilibration test were recorded. Ultra-performance liquid chromatography

(UPLC) coupled with Q-TOF mass spectrometry were conducted to explore the metabolic profile in serum sample. After raw data acquisition and transformation by Agilent Masshunter Qualitative Analysis software, Mann-Whitney U Test Erythromycin and fold change analysis were performed to find the feature difference. Finally the different metabolites were defined by on-line software. Results: Eighteen (male/female, 10/8; age, 61.4 ± 18.1 years) PD patients with ESS ≥ 9 were assigned into EDS group, while 18 selected gender matched patients (age, 56.9 ± 12.9 years) were defined non-EDS group. Changes of metabolites with significant difference between groups can be classified into three metabolic pathways. They were amino acids, tricarboxylic acid cycle, and lipid metabolism. (Table 1). Scores of principal components between groups were illustrated in a 3D PCA plots. (Figure 1). Conclusion: Present study provided potential application of metabonomics in early diagnosis and new insight into mechanism of EDS in peritoneal dialysis patients.

In this study we have shown the ability to select, from a large non-immune repertoire of human Fab fragments, a panel of recombinant Abs with TCRL specificity directed to auto-reactive T-cell epitopes in the form of self-peptide presented by MHC-II. Abs directed to MHC-II–peptide complexes have been generated before, using epitope-specific immunization as the initial step for further conventional hybridoma technology or construction of a phage display library 35–39. We report here, for the first time, the generation of MHC-II–peptide TCRL Fabs from a naïve human Ab library.

Moreover, due to the GSK1120212 clinical trial large size of our phage display library, we were able to isolate several different Fabs directed to each targeted MHC-II peptide complex. Based JAK inhibitor on our successful

experience in the generation of MHC I–peptide TCRLs and the current data, we believe that the described method can be duplicated for a relatively rapid generation of TCRL Fabs directed to other MHC-II–peptide complexes. We isolated five different TCRL Fab clones directed to the minimal two-domain DR2–MOG-35-55 (RTL1000) complex. Characterization of these Fabs indicated a requirement for both DR2 and MOG-35-55 peptide for recognition. The Fabs could further discern conformational differences in the P42S variant of DR2-bound MOG-35-55 peptide present in RTL342m, demonstrating individual variation in binding to specific contact residues within the DR2–MOG-35-55 complex. Moreover, cross-recognition of RTL342m by the 2E4 NADPH-cytochrome-c2 reductase Fab allowed neutralization of RTL treatment of mMOG-35-55-induced EAE, illustrating the functional activity of this highly characterized Fab in vivo. These Abs therefore mimic the fine specificity of TCRs with the advantages of high-affinity and stable characteristics of the recombinant Fab fragment. Our TCRLs exhibited high structural sensitivity while firmly distinguishing two- versus

four-domain MHC-II–peptide complexes. None of the anti-RTL1000 TCRL Fabs were able to recognize four-domain DR2–MOG-35-55 presented by APC or in a recombinant form. Similarly, two panels of TCRL Fabs directed to two- or four-domain DR4–GAD-555-567 complexes clearly distinguished these two conformational MHC-II peptide determinants. While our previous biophysical and biochemical data suggest a similar secondary structure content for the RTL constructs and the peptide-binding domains of native MHC, our novel TCRL Fabs have identified distinct conformational differences between MHC-II–peptide and RTL–peptide complexes. This novel finding suggests that autoreactive four- versus two-domain MHC-II TCR ligands have distinct conformational shapes that can be distinguished by human Fab molecules and that apparently confer opposing immunological functions (peptide-specific T-cell activation versus tolerance).