This commonly results in direct sensitization against the partner, potentially making
him an unsuitable donor. HAR may also occur in blood group incompatible transplantation without desensitization. Preformed antibodies cause rejection by binding to HLA antigens expressed on the endothelium of vessels in the transplanted kidney, resulting in activation of the complement cascade with resultant thrombosis and infarction of the graft (reviewed in2). HAR can occur immediately upon reperfusion of Ibrutinib the donor kidney. This catastrophic outcome necessitates the immediate removal of the graft. Clearly avoiding HAR is desirable and crossmatching helps predict and hence prevent this.3 In brief, a crossmatch involves placing recipient serum (potentially containing donor-specific anti-HLA antibodies) onto donor lymphocytes (containing HLA antigens). A cytotoxic reaction (deemed ‘positive’) suggests the presence of preformed DSAbs. A more detailed description is provided later in this manuscript. A 44-year-old woman with end-stage renal failure secondary to reflux nephropathy is interested in a renal transplant and her husband has offered to be a donor. They are of the same blood group but are unmatched on tissue typing (0/6 HLA matches at the HLA-A, -B and -DR loci). They have a complement-dependent cytotoxicity (CDC) crossmatch performed as part of their initial assessment, which shows a positive result for both the T- and B-cell crossmatch (Table 1). Is it safe
to Glycogen branching enzyme proceed? It is not safe to proceed in light of these crossmatch results but clarification steps are needed to better
understand Target Selective Inhibitor Library concentration the reason for the positive results. This could be a falsely positive result (technical issue) or there may be autoantibodies (against lymphocyte antigens) present in the recipient serum. Autoantibodies are generally IgM rather than IgG antibodies. To establish if autoantibodies are responsible for the result an auto-crossmatch should be performed. In this assay, recipient serum is crossmatched against recipient (rather than donor) lymphocytes. Second, the original crossmatch should be repeated with the addition of the agent Dithiothreitol (DTT). DTT reduces the disulfide bonds in IgM thereby preventing IgM antibodies from generating a positive result. IgM antibodies are generally regarded as having no pathological significance in transplantation.4–7 If a repeat crossmatch with DTT is negative then it may be safe to proceed with the transplant. An auto-crossmatch adds weight to this analysis by determining if the recipients are reacting against their own T or B cells in a similar way (Table 2). These results suggest that the reaction of the recipient to the donor is on the basis of autoantibodies. This means that the transplant could proceed using this pairing; however, before most live donor transplants and indeed cadaveric transplants more information is routinely available that aids in forming a more complete assessment of immunologic risk.
PAR-1, PAR-2 and PAR-3 were amplified with 35 cycles (94 °C for 30 s, 55 °C for 30 s, 72 °C for 60 s). PAR-4 was amplified with 35 cycles (94 °C for 30 s, 55 °C for 30 s, 72 °C for 30 s). Beta-actin (β-actin) was used as positive control using the following primer sequences: PD-0332991 in vitro β-actin (sense) 5′-CCAAGGCCAACCGCGAGAAGATG-3′ and β-actin (antisense) 5′-AGGGTACATGGTGGTGCCGCCAG-3′; yielding a expected PCR product of 587 bp. Beta-actin was amplified
with 35 cycles (94 °C for 60 s, 60 °C for 90 s, 72 °C for 60 s). Negative control was performed for each reaction and included the omission of the reverse transcriptase or the omission of cDNA in the PCR mix. PCR products were resolved on a 1.5% agarose gel for visualization. Flow cytometry analysis was performed of the freshly isolated naïve CD14+ monocytes and the CD14+ monocytes cultured for 24 h with experimental conditions. Briefly, the freshly isolated naïve CD14+ monocyte cell pellet was washed in PBS containing 1% BSA and 0.1% Na-azide and subsequently used for incubation with fluorochrome-labelled antibodies. The CD14+ monocytes cultured with experimental
conditions for 24 h were placed on ice for 1 h. Subsequently, medium with CD14+ monocytes was transferred to 1.5-ml tubes and centrifuged at 900 g for 5 min at room temperature. Supernatants were harvested; the remaining CD14+ cell pellet was washed in PBS containing 1% BSA and 0.1% Na-azide, and centrifuged at 900 g for 5 min at room temperature. After centrifuging, Mirabegron freshly isolated naïve CD14+ monocytes as well as cultured CD14+ monocytes 3-deazaneplanocin A nmr were incubated with APC-conjugated monoclonal mouse anti-human CD14 antibody, PE-conjugated monoclonal mouse anti-human PAR-1 (ATAP2) antibody, FITC-conjugated monoclonal mouse anti-human PAR-2 (SAM11) antibody, PE-conjugated monoclonal mouse anti-human PAR-3 (8E8) antibody, FITC-conjugated polyclonal rabbit anti-human PAR-4 (APR-034-F)
antibody, PE-conjugated monoclonal mouse anti-human TF (HTF-1) antibody, and APC-, PE- and FITC-conjugated isotype control antibodies for 30 min at 4 °C in the dark. After a final washing and centrifuging step, cells were fixated in 2% paraformaldehyde. All cells were analysed using the FACS Calibur (BD Biosciences) and FlowJo software (Tree Star Inc., Ashland, OR, USA). For cytokine assays, naïve PBMCs and naïve CD14+ monocytes recuperated for 24 h and subsequently cultured according to the experimental conditions for 24 h were used. Supernatants were harvested, transferred to 1.5 ml tubes, centrifuged at 900 g for 5 min at room temperature and cryopreserved at −80 °C. Cytokine production (IL1-β, IL-6, IL-8, IL-10 and TNF-α) was determined in triplicate. Standard and positive control recovery for each ELISA assay was between 90–110%.
Surgical drainage (and sometimes excision) of infected lymph nodes and abscesses involving the liver, skin, rectum, kidney and brain is often necessary for healing, particularly for the visceral abscesses. Daily prophylaxis
with Bactrim and/or Itraconazole is recommended during infection-free periods. For more detailed treatment see more options, the interested reader is referred to Roos et al. . One of the main reasons to make a rapid diagnosis of the severe forms of CGD is that such patients may be treated successfully with a bone marrow transplant [7-9]. A few reports suggest that gene therapy may eventually be successful both in X-linked and autosomal CGD [10, 11]. Thus, there are many reasons to identify precisely the genetic defect in patients with CGD. Patients suspected of suffering from CGD (Table 2) must be diagnosed by the inability of their blood phagocytes to generate
reactive oxygen species. This can be performed in various ways. The woman is a relative (mother, sister, daughter, maternal aunt, maternal grandmother) of a CGD patient The woman has symptoms of CGD (see Table 2a) The woman is a relative of a CGD patient R788 and has discoid lupus symptoms Carriership or occurrence of CGD should be tested functionally [NADPH oxidase activity in the neutrophils with a per-cell assay, e.g. nitro-blue tetrazolium (NBT) slide test or dihydrorhodamine-1,2,3 (DHR) assay] and genetically Cell press Usually, purified blood neutrophils  are used for these tests, but total leucocytes or even diluted full blood can also be used. Blood can be sent by courier to the testing laboratory, but several precautions must be taken. Ethylenediamine tetraacetic acid (EDTA) or heparin blood can be used for NADPH oxidase activity testing and for preparation of neutrophil lysate for NADPH oxidase component expression by Western blot. In the case of EDTA blood, the neutrophil fraction purified from it must
be recalcified and left for 30 min at room temperature before NADPH oxidase activity can be measured. For DNA preparation, EDTA blood is superior. The blood transport must take place in polypropylene tubes (completely filled) and at room temperature. This means, for instance, no transport in plane cargo compartments. The blood must arrive at the place of investigation within 48 h after vena puncture, preferably within 24 h. A control blood sample must be shipped together with the sample from the presumed patient and/or relative(s). All assays must be performed in parallel with the control cell preparation. The NADPH oxidase enzyme that is affected in CGD reduces molecular oxygen to the one-electron radical superoxide (O2−), which is subsequently reduced further to hydrogen peroxide (H2O2). The reducing equivalents for this reaction are derived from NADPH, which is converted into NADP+ and H+.
In conclusion, the results of the present study suggested that upregulation of IL-21 and IL-10 and downregulation Z-VAD-FMK price of IL-4
in periodontitis tissues may be collectively involved in the increased levels of salivary IgA in chronic periodontitis subjects. Since only cytokine profiles and salivary IgA level were evaluated and, no characterization of naïve B cell switch in the periodontal lesions was performed, these preliminary findings are still not enough to definitely define the mechanisms of Ig isotype switching on chronic periodontitis. However, our results may provide new insights into the possible role of Th-secreted cytokines in driving humoral immune response on periodontal tissue breakdown. The authors thank Ms Jeruza P. Bossonaro for technical assistance and São Paulo State Research Foundation (São Paulo, São Paulo, Brazil) for its financial support (# 2008/09687-0; # 2008/04280-0). “
“This chapter contains sections titled: The immune system Tissues and
cells of the immune system Activation, regulation and functions of immune responses Innate versus adaptive immunity Primary and secondary immune responses Immune cell development Mast cells and basophils Eosinophils Neutrophils Monocytes and macrophages Dendritic cells Natural killer cells CD4+ T helper cells CD8+, cytotoxic T cells B cells γδ T cells learn more Natural killer T cells Anatomy of the immune system Lymph nodes Spleen Summary “
“Although Fasudil has shown therapeutic potential in EAE mice, the mechanism of action are still not fully understood. Here, we examined the immunomodulatory effect of Fasudil on encephalitogenic mononuclear cells (MNCs), and tested the therapeutic
potential of Fasudil-treated MNCs in active EAE. Fasudil inhibited expression of CCL20 on T cells and migration of T cells, decreased CD4+IFN-γ+ and CD4+IL-17+ T cells, but increased CD4+IL-10+ and CD4+TGF-β+ PLEK2 T cells. Fasudil reduced expression of CD16/32 and IL-12, while elevating expression of CD206, CD23, and IL-10. Fasudil also decreased levels of iNOS/NO, enhanced levels of Arg-1, and inhibited the TLR-4/NF-κB signaling and TNF-α, shifting M1 macrophage to M2 phenotype. These modulatory effects of Fasudil on T cells and macrophages were not altered by adding autoantigen MOG35–55 to the culture, i.e., autoantigen-independent. Further, we observed that, in vitro, Fasudil inhibited the capacity of encephalitogenic MNCs to adoptively transfer EAE and reduced TLR-4/p-NF-κB/p65 and inflammatory cytokines in spinal cords. Importantly, Fasudil-treated encephalitogenic MNCs exhibited therapeutic potential when injected into actively induced EAE mice. Together, our results not only provide evidence that Fasudil mediates the polarization of macrophages and the regulation of T cells, but also reveal a novel strategy for cell therapy in MS.
One week after the last immunization, mice were killed, blood was taken and, following perfusion, intestinal samples were collected using the perfusion-extraction (PERFEXT) technique.20 Ovalbumin-specific IgG and IgA titres were determined by ELISA. Cabozantinib research buy Ninety-six-well plates (Greiner Bioscience, Frickenhausen, Germany) were coated with OVA (20 μg/ml)
and blocked with PBS/BSA. Serially diluted serum and intestinal samples were added followed by goat anti-mouse horseradish peroxidase-conjugated IgA or IgG (SouthernBiotech, Birmingham, AL). Plates were developed with o-phenylenediamine dihydrochloride, stopped with 0·1 m H2SO4 and absorbance was read at 490 nm. Titres of IgG and IgA were determined from the sample dilution giving an optical density value above 0·4. Data were statistically analysed in Prism (graphpad software) using the Student’s t-test, in which *P < 0·05, **P < 0·01 and ***P < 0·001. Although systemic immune compartments and skin-draining LN of CD47−/− mice have been extensively studied, the GALT has not been carefully characterized. We
therefore enumerated cells in the GALT of CD47−/− mice and revealed a 50% reduction of total cell numbers in MLN, LP and PP, compared with those in WT mice (Table 1). In contrast, the number of cells in skin-draining LN and spleen was not significantly different between WT and CD47−/− mice (Table 1). Although immunohistochemical analysis showed normal localization of T and B cells in MLN and PP of CD47−/− mice find more (see supplementary material, Fig. S1a), and both CD47−/− and WT CD4+ T cells in PP and MLN were found to express similar levels of CD44 and CD62L (data not shown), the frequency of CD4+ T cells in MLN and PP of CD47−/− mice was significantly reduced compared with that in WT mice (Fig. S1b). In contrast, the frequency of Foxp3+ CD4+ T cells in PP, but not in MLN, was significantly increased in CD47−/− compared with WT mice (Fig. S1c). Impaired DC migration from the skin and subset-specific DOK2 alterations in splenic DC at steady state have previously been
reported in CD47−/− mice13,14 therefore, we next assessed populations of antigen-presenting cells in the GALT of these mice. As the total number of cells in the GALT of CD47−/− mice was reduced by 50%, frequency rather than total number of cells within cell populations was determined. Flow cytometric analysis showed a significant reduction in the frequency of CD11c+ MHC-II+ conventional DC (cDC) in MLN, but not in LP or PP, of CD47−/− mice (Fig. 1a). In contrast, no significant change in the frequency of CD172a+ CD11clow MHC-IIlow SSClow cells was detected (Fig. 1b). Further phenotypic characterization was therefore focused on cDC and identified two populations of cDC in MLN (see supplementary material, Fig. S2a).
, 1988). Notably, nonencapsulated pneumococci show more autolysis and release more pneumococcal RNA during growth than encapsulated pneumococci (Vered et al., 1988; Fernebro et al., 2004). Moreover, increased autolysis in nonencapsulated strains compared to encapsulated strains may even have underestimated the higher viable counts in our study. Secreted bacterial RNA fragments may impact pathogenesis (Obregon-Henao et al., 2012). The contribution PI3K Inhibitor Library of S. pneumoniae virulence factors
in host respiratory colonization and disease varies according to the in vivo location of the bacterium. In line with our findings, others described previously that nonencapsulated pneumococci possess increased resistance against cationic antimicrobial peptides compared to encapsulated pneumococci (Beiter et al., 2008). Pneumococcal resistance to extracellular neutrophil proteases may be of greater relative importance than inhibition of opsonophagocytosis on the mucosal surface in comparison with other body compartments such as the bloodstream or lung parenchyma. On the mucosal surface, phagocytosis may be ineffective, but neutrophil degranulation and release Opaganib concentration of toxic substances including neutrophil proteases may effectively kill pneumococci. However, definitive in vivo data demonstrating the contribution of extracellular killing of pneumococci are lacking (Coonrod
et al., 1987). We conclude that human neutrophil proteases elastase and cathepsin G are active against pneumococci in general; however, nonencapsulated pneumococci show increased resistance to extracellular human neutrophil protease-mediated check killing compared to encapsulated pneumococci. The mechanism of this increased resistance and the effect on human colonization and (mucosal) infection remain to be elucidated. The authors declare that no conflict of interest exists. “
“In June 2009, the National Institute of Allergy and Infectious Diseases (NIAID), Division of Allergy, Immunology
and Transplantation (DAIT), sponsored a workshop entitled Mast Cells in Innate and Adaptive Immunity. International experts in mast cell biology discussed recent advances in the field and future areas of research aimed at advancing our understanding of the importance of mast cells in shaping nonallergic, adaptive immunity to infection. Since 1954, the National Institutes of Health (NIH) has funded over 1000 grants related to mast cells 1. Of these, less than 10% have focused on mast cell responses to viruses, bacteria or helminths with the majority being directed to the study of mast cell mediators and allergic diseases. Thus, while the functions of mast cells in allergic diseases have been extensively studied, their role as effector cells against pathogens is poorly understood. The importance of mast cells for host defense is underscored by two observations: first, mast cells are found in lower organisms that developed several hundreds of million years ago, and second, no humans lacking mast cells have been described so far.
We postulate that the affinity of this mAb for the canine epitope is low, a view supported by a recent study in which a specific anti-canine CD25 this website mAb was developed in mice.55 A proportion of the ACT-1-negative cells may therefore be CD25+, which would reconcile this apparent anomaly with the observation that the majority of Foxp3/FOXP3+ T cells in both rodents and humans are CD25+. Stimulation of mononuclear cells derived from peripheral LNs with Con A for up to 120 hr elicited a significant increase in percentage and MFI of FOXP3 expression by both CD4+
and CD8+ T cells (Fig. 2). This phenomenon occurred in the absence of exogenous IL-2 or TGF-β, though the addition of low concentrations of IL-2 augmented CD25 and FOXP3 expression (Fig. 3a). Robust increases in CD25 expression were also observed in a recent study of CD4+ T cells derived from PB stimulated with Con A, yielding parallel increases in FOXP3 expression.64 However, similar experiments performed in an earlier study failed to elicit significant increases in the proportions of FOXP3+ CD4+ T cells without the addition of IL-2 and TGF-β,49 PS-341 manufacturer presumably reflecting differences in experimental conditions. Interestingly, in our study removal of the stimulus and continued culture disclosed a FOXP3high
population of lymphocytes that was IFN-γ− and predominantly CD4+ (Fig. 2d). Both the high level of FOXP383,84 and the lack of IFN-γ expression – Foxp3 directly represses the Ifng gene85,86 – suggested that this population was regulatory in nature, supported by our subsequent functional studies in vitro (Fig. 3d). Two alternative, non-mutually exclusive explanations for the increased proportion and absolute numbers of FOXP3+ T cells with polyclonal stimulation were considered – namely, up-regulation of FOXP3 in cells
that were originally either FOXP3intermediate or FOXP3−, or proliferation of pre-existing FOXP3+ T cells. The impressive increase in MFI of FOXP3 suggested that up-regulation of this molecule had occurred in individual cells, but parallel proliferation of pre-existing Treg cells could not be excluded. Reasoning that in both mice and humans Helios expression is restricted to nTreg cells and is not of induced by stimulation, even in the presence of TGF-β, we explored the expression of Helios in cells that had been stimulated in an identical manner to those for the functional studies. We observed an impressive increase in the number of FOXP3+ Helios+ cells with Con A stimulation, arguing for the proliferation of pre-existing nTreg cells. However, Helios expression was not limited to the FOXP3high population, which we speculated were Treg cells on the basis of their IFN-γ− phenotype in earlier studies (Fig. 2d).
Co-stimulation is not only relevant for the generation of effector T cell responses; several co-stimulatory molecules, including CD134 (OX-40), CTLA-4 and ICOS, have been indicated to also contribute to tolerance mechanisms mediated by Tregs[24,25]. CD137 expression has been found on Tregs and CD137 signalling has been shown to promote proliferation and survival of Tregsin vitro[26,27]. In a murine model of diabetes, treatment with anti-CD137 mAb increased Treg numbers significantly, which
mediated protective effects after adoptive transfer into non-obese diabetic–severe RG7204 combined immunodeficiency (NOD–SCID) recipients . In contrast, other studies have pointed towards a negative effect of CD137 stimulation on Treg induction or activity. Choi
et al. demonstrated that CD137 signalling neutralizes the suppressive function of Tregsin vitro and in vivo. Another study suggests that CD137 signalling is not important for Treg function, as Tregs isolated from CD137−/− mice prevented colitis pathology efficiently in a CD4+ T cell transfer model to SCID mice . So far, the exact importance of the CD137/CD137L pathway for Treg function or generation of respiratory tolerance in vivo has not been studied. Therefore, we also investigated whether CD137 might play an immune regulatory role in vivo. CD137 deficiency had no impact on respiratory tolerance induction in our model, as CD137−/− mice were protected equally from the development of allergic parameters www.selleckchem.com/products/ABT-263.html compared to WT mice by mucosal antigen application prior to sensitization. We could not detect changes in Treg frequencies between WT and CD137−/− mice. Thus, the lack
of CD137 seems not to inhibit Treg development or function in our model. Taken together, our results demonstrate that loss of CD137/CD137L signalling neither affects the generation of Th2-mediated allergic airway inflammation nor influences the induction of respiratory tolerance Molecular motor in our murine model. While the current study investigated the role of CD137 in a murine model of allergic asthma, there are only limited data on CD137 function in the human system with regard to allergic, Th2-mediated immune responses: CD137 expression has been detected on eosinophils and associated with apoptosis of eosinophils . Moreover, CD137 expression has been reported on T cells infiltrating the conjunctival stroma in patients with severe allergic conjunctivitis compared with controls . Thus, future studies are required to elucidate the exact role of CD137 signalling in allergic diseases in humans. This study was supported by the German Research Foundation [Research Training Group GRK 1441 ‘Allergic response in lung and skin’; SFB 578 (TP14) ‘Immune reactions of the lung in infection and allergy’].
The authors would like to thank Ane M Rulykke for excellent technical assistance. We would like to thank Jesper Jurlander for sharing reagents and ideas. Anti-CD20 antibodies were a kind gift from Mark S. Cragg and Claude H.T. Chan, whom we would also like to thank for scientific discussions. We would like to thank Esben G. Schmidt for technical support and Morten Rasch for advice on protease inhibition. This work was made possible by the University of Copenhagen, Faculty of Health Sciences and The Neye Foundation. The authors declare to have no financial conflicts or interest. “
“Formation https://www.selleckchem.com/products/DAPT-GSI-IX.html of immune synapses (IS) between T cells and
APC requires multiple rearrangements in the actin cytoskeleton and selective receptor accumulation in supramolecular activation
clusters (SMAC). The inner cluster (central SMAC) contains the TCR/CD3 complex. The outer cluster (peripheral SMAC) contains the integrin LFA-1 and Talin. Molecular mechanisms selectively stabilizing receptors in the IS remained largely unknown. Here, we demonstrate that sustained LFA-1 clustering in the IS is a consequence of the combined activities of the actin-bundling protein L-plastin (LPL) and calmodulin. Thus, upon antigen-recognition of T cells, LPL accumulated predominantly in the peripheral SMAC. siRNA-mediated knock-down of LPL led to a failure of LFA-1 and Talin redistribution – however, not TCR/CD3 relocalization – into the IS. As a result of this LPL knock-down, the T-cell/APC interface became smaller over time and T-cell proliferation was inhibited. Importantly, Procaspase activation binding of calmodulin to LPL was required
for the maintenance of LPL in the IS and consequently inhibition of calmodulin also prevented stable accumulation of LFA-1 and Talin, but not CD3, in the IS. During the activation of T cells Phospholipase D1 the immune synapse (IS) is formed at the area of interaction between T cells and APC 1, 2. The IS is involved in enhancing, directing and terminating the T-cell immune response (for review, see 3–7). Within the IS, surface receptors as well as intracellular signaling and scaffolding proteins are organized in distinct structures, which are called supramolecular activation clusters (SMAC). The inner cluster (central SMAC or cSMAC) contains PKCΘ and the TCR/CD3 complex. The outer cluster (peripheral SMAC or pSMAC) is composed of the integrin LFA-1 (CD11a/CD18) and Talin 8. It is clear that for the development of an IS the actin cytoskeleton is of special importance 2, 9–11. For construction of an actin meshwork, as it is found in the IS, crosslinking and bundling of F-actin is indispensable to support F-actin rigidity. Here, we demonstrate that the actin-bundling protein L-plastin (LPL) is an important component to orchestrate the ordered formation of a mature IS. LPL is a leukocyte-specific protein.
We found that T. cruzi infection led to increased expression of PD-1 and its ligands on peritoneal Mφs as well as during in vitro infection. On the other hand, F4/80+ Mφs from T. cruzi-infected mice suppressed the proliferative response of naive CD90.2+ T cells to primary stimulation with Con A. The PD-L1 or PD-1 blockade significantly reduced the suppressive
activity of T. cruzi-infected-Mφs, indicating that PD-L1 is directly involved in their suppressive activity. However, PD-L2 blockade was not able to restore the T-cell proliferation suppressed by T. cruzi-infected Mφs. Given that it has been demonstrated that PD-L2 Volasertib datasheet KO mice show an increase in Th2 response,47,48 we decided to evaluate if PD-L2 blockade was able to induce Arg I. Involvement of Arg I in the suppressive AP24534 ic50 capacity of Mφs has been broadly demonstrated.26,27,60 Our data showed that PD-L2 blockade in T. cruzi-infected Mφs induced Arg I activity and expression that might explain the immunosuppressive capacity of these Mφs. However, we did not see changes in Arg I expression and activity in cell cultures treated with PD-1 or with PD-L1 blocking antibodies. Therefore,
in our T. cruzi infection model the immunosuppression may be directly mediated by PD-1/PD-L1 and indirectly by PD-L2 through Arg I regulation. Moreover, supporting data demonstrated that Arg I plays a key role in T-cell suppression in non-healing leishmaniasis lesions.26 Arg I, through the local depletion of l-arginine, impairs at the site of lesions the capacity of T cells to proliferate and to produce IFN-γ, which is required for parasite elimination.26 However, during Schistosoma mansoni infection, Arg I from Mφs favours the recovery of the infection by inhibiting T CD4+ cells and the production of cytokines.
The authors demonstrated Thymidine kinase that the primary suppressor mechanism was the depletion of arginine by Arg I from Mφs.60 Here, we show that PD-L2 blockade as well as PD-L2 deficiency enhances Arg, leading to an increase in parasite proliferation. In addition, Terrazas et al.38 have shown that Taenia crassiceps-induced Mφs were able to suppress T-cell proliferation through PD-L1 and PD-L2 up-regulation on Mφs in an IL-10, IFN-γ, NO independent and cell-to-cell contact dependent manner. In addition, Schistosoma mansoni worms selectively up-regulate PD-L1 to reduce T-cell activation during early acute stages of infection before the subsequent emergence of egg-induced T-cell suppression in the chronic stages of infection.61 Recently, It was shown that IL-4-stimulated Mφs up-regulate PD-L2 and the T-cell suppression induced by these Mφs was restored by adding anti-PD-L2 blocking antibodies.62 Therefore, T-cell suppression could be mediated by PD-L1 or PD-L2, depending on the manner in which Mφs are stimulated.