TRAMP PCa cells retrovirally transduced to express human PSMA (TR

TRAMP PCa cells retrovirally transduced to express human PSMA (TRAMP-PSMA+HHD−) and/or HHD (TRAMP-PSMA+HHD+) or (TRAMP-PSMA−HHD+) were used as targets. The PSMA27, PSMA663, and PSMA711-specific CTLs demonstrated high levels of cytolytic activity (over 75% specific lysis) against target cells loaded with the respective PSMA peptide (Fig. 3A–C). The PSMA27 and PSMA663-specific CTLs were also able to specifically and effectively kill the target cells endogenously

expressing human PSMA and HHD (approximately 60 and 75% specific lysis, respectively, Fig. 3A and B). This confirms the processing and presentation of both PSMA27 and PSMA663 peptides from the protein backbone. However, despite displaying

high cytotoxic capacity against peptide-loaded cells, the PSMA711-specific CTLs were unable to kill the human PSMA and HHD-expressing cells RG7204 cell line (Fig. 3C). These observations were confirmed in multiple experiments and indicate that the PSMA711 peptide may be poorly processed and presented. As strong ex vivo CD8+ T-cell responses were generated against p.DOM-PSMA27 and p.DOM-PSMA663 constructs (Fig. 1B), and these CTLs were able to specifically lyse target cells which expressed PSMA endogenously (Fig. 3A and B), the in vivo MG-132 price cytotoxicity of these CTLs was investigated. Testing of the ability of the CTLs induced in HLA-A*0201 transgenic mice to kill tumor cells in vivo is hampered by the fact these mice lack expression of endogenous mouse MHC class I (H-2b) antigens. This means that the H-2b antigens expressed by the TRAMP PCa cell line will be immunogenic, preventing their long-term survival in standard tumor challenge experiments. We therefore used two approaches: the first was to demonstrate that the induced CD8+ T cells could kill peptide-loaded autologous target cells (splenocytes; Fig. 4A–C). For this, mice were immunized with p.DOM-PSMA27, p.DOM-PSMA663, or p.DOM control vaccine and boosted 28 days later with electroporation. Eight days after boosting, CFSE-labeled HHD splenocytes loaded with PSMA27, PSMA663, or control peptide

were injected as target cells. Representative flow cytometry plots are shown in Fig. 4A. Mice vaccinated with p.DOM-PSMA27 had a significantly reduced ratio of surviving CFSEhi PSMA27-loaded Sulfite dehydrogenase cells in respect to CFSElo control cells, with ∼33% fewer cells persisting compared with those in control mice (p=0.0011, Fig. 4B). The level of lysis of target cells observed in individual mice correlated with IFN-γ ELISpot responses detected in vitro (p=0.0049, Fig. 4B). After p.DOM-PSMA663 vaccination, the effect was even greater, with an approximately 50% reduction in the survival of PSMA663-positive cells in the vaccinated group compared with controls (p=0.0076, Fig. 4C). Again the level of lysis of target cells correlated with IFN-γ ELISpot responses (p<0.0001, Fig. 4C).

To date, the enhancement of Ab synthesis mediated by IFN-β treatm

To date, the enhancement of Ab synthesis mediated by IFN-β treatment is not resulting in an excessive Ig production or in an induction of auto-Abs (data not shown and [46]). Rather, this therapy restores via monocyte-mediated bystander mechanisms the correct TLR7 responsiveness of MS-derived B cells, which in this way fully acquire the capacity to mature into Ig-producing cells, similar to HDs. In this

scenario, the study from Warrington et al. [47] is of great interest that demonstrates how naturally occurring polyclonal human Abs (in particular IgM) can strongly promote remyelination inducing a transient Ca2+ influx in myelin-forming cells. Thus, the ability of IFN-β therapy to induce polyclonal Abs (and in particular IgM) with potential remyelinating activity reveals another mechanism of protection possibly mediated by this drug, that could lead to amelioration of PI3K Inhibitor Library mw neurological symptoms in MS patients. An additional aspect to take into account from our findings is that the deficient TLR7-induced IgM and IgG production observed in MS patients might correlate with worsening of disease or impaired immune responses against infections with TLR7-recognized RNA viruses, such as influenza, or upon vaccination. Many studies have been conducted in this regard. Different groups have reported that the risk of relapse is increased in individuals with MS bacterial or viral infections [48, 49]. In the case of acetylcholine influenza,

it was shown that the reduction of infection episodes leads to a lower number of exacerbations in MS sufferers. In a study with 180 RRMS patients, 33% of individuals, who became infected with this virus, developed an acute relapse within 6 weeks [50]. However, randomized, double-blind, placebo-controlled studies during the past decade have shown that influenza vaccination of MS patients neither increases the relapse rate nor worsens the course of disease [51]. Indeed, the administration

of standard vaccines in MS patients is considered safe worldwide, it follows the same recommendations as in healthy adults and actually should be recommended to MS patients in order to avoid attacks of the disease [52]. Having all this in mind, it cannot be excluded that our data on the reduced level of secreted Abs in response to TLR7 stimulation can have a role in the exacerbation of relapses observed in MS-affected individuals along episodes of influenza infection. The increasing recognition that viruses, and in particular EBV, can be etiological factors driving the development of MS or other autoimmune diseases in genetically susceptible individuals further strengthens the potential of administering anti-viral therapies to people affected by these disorders [12]. In line with this view, the increased TLR7 gene expression observed upon IFN-β might be part of a specific antiviral program induced by this cytokine that could counteract dysregulated responses to viral infection in MS patients.

This study was supported by the Key Project of Chinese National P

This study was supported by the Key Project of Chinese National Programs (2008ZX10003-010), National Natural Science Foundation of China 30670108 and J0730860, RFDP20060246037, and the Intramural Research Program of

the National Institute of Allergy and Infectious Diseases, The National Institutes of Health, USA. C.W. and J.F. contributed equally to this work. “
“Immunoassay designs rely on the great specificity of antibodies and a suitable marker that facilitates generation of a quantitative signal. Currently, selleckchem there is no reliable method for measuring the titers of an anti-idiotypic antibody. Our initial attempt to measure titers of mouse anti-idiotypic antibody after idiotypic vaccination with HM-1 killer toxin neutralizing monoclonal antibody (nmAb-KT) failed.

Because the injected antigen, nmAb-KT, is a mouse IgG, using a commercial antibody to measure the antibody titer always gave a false positive signal against control mouse serum antibody in parallel with the antigen-treated immunized serum antibodies. To get a reliable and clearly differentiable signal by ELISA, idiotypic antigen was labeled with HRP and HRP-conjugated-nmAb-KT used to measure the antibody titers in the antigen-treated mice. Compared with control mice, signals were found in high anti-nmAb-KT IgG responses in test mice; however, PF 2341066 untreated control mice had a significant amount of purified non-specific IgG. This method is amenable to long read lengths and will likely enable anti-idiotypic antibody titer measurement in a more specific and cost effective way without requiring commercial antibody. “
“This study aimed to comprehensively describe inflammatory responses to trivalent influenza virus vaccine (TIV) among pregnant women and determine whether responses differ compared to non-pregnancy. Twenty-eight pregnant and 28 non-pregnant women were vaccinated. Serum cytokines were measured at baseline, and 1, 2, and 3 days post-vaccination. Anti-influenza antibody titers were measured at baseline and 1 month post-vaccination.

Overall, following vaccination, tumor necrosis factor (TNF)-α Isoconazole and interleukin(IL)-6 increased significantly, peaking at 1 day post-vaccination (P’s < 0.001). Pregnant versus non-pregnant women showed no differences in IL-6, TNF-α, or IL-1β responses. Pregnant women showed no change in IL-8 and increases in migration inhibitory factor (MIF), while non-pregnant showed decreases in both. Pregnancy did not significantly alter antibody responses. Inflammatory responses to TIV are mild, transient, and generally similar in pregnant and non-pregnant women. Given the variability evidenced, vaccination may provide a useful model for studying individual differences in inflammatory response propensity. "
“One morning last December on my way to work, something strange happened.

IL-21 has been implicated in the pathogenesis of type 1 diabetes

IL-21 has been implicated in the pathogenesis of type 1 diabetes on the basis of the knowledge of the immune pathophysiology of a non-obese diabetic (NOD) mouse

strain [13, 14]. IL-21 stimulates the proliferation of both T and B cells and terminal differentiation of natural killer (NK) cells, enhances the cytotoxic activity of CD8+ T cells [15-17], counteracts the suppressive effects of regulatory T cells [18] and stimulates non-immune cells to generate inflammatory mediators [19]. Recently, the importance of IL-21 [20] and its related T helper type 17 (Th17) cells [21, 22] has emerged in the pathogenesis of type 1 diabetes as well in other autoimmune diseases [23, 24] in humans. The Th-cell-subset-specific expression of the IL-21 proximal promoter is controlled via the action of several transcription factors, including

nuclear factor-activated T cells, cytoplasmic 2 (NFATc2), T-bet and leucine-zipper transcription factor Maf (c-MAF) [25, 26]. Due to the pleiotropic effects of IL-21 on immune regulation, it is important to elucidate the genetically driven changes in its function and regulation that FK228 mouse might affect the autoimmune process and cause beta cell destruction. The presence of autoantibodies against islet-cell antigens is the first indication of diabetes development and is a well-established fact. Currently, four autoantibodies are used to predict the development of T1AD: antibodies against glutamic acid decarboxylase (GAD65), tyrosine phosphatase-like protein (ICA512, also termed IA-2), insulin and the recently discovered zinc T8 transporter (ZnT8) [1, 2, 27]. T1AD is also associated frequently with other immune-mediated disorders [27, 28] such as autoimmune thyroiditis [29, 30], Addison’s disease [31], pernicious anaemia [32, 33] and coeliac disease [30, 34]. During the past few years, extensive research has been conducted to predict the occurrences of autoimmune diseases through the detection of organ-specific antibodies in T1D patients [27, 35]. Early detection of antibodies and latent organ-specific

dysfunction is important to alert physicians to take appropriate Molecular motor measures to prevent the progression to full-blown disease. Several autoimmune diseases are related to T1AD and elevated IL-21 expression in both human and animal models, as well as to a high frequency of the PTPN22 C1858T polymorphism. The Brazilian population is one of the most heterogeneous in the world, composed mainly of European (Caucasian descent, 0·771), African (0·143) and Amerindian (Native South American, 0·085) ancestry [36]. We hypothesized that the variants of these genes that regulate immune function would influence not only diabetes risk, but also the expression of other tissue-specific autoantibodies among patients with T1D in a Brazilian population.

However, eosinophils were not able to ingest non-opsonized yeasts

However, eosinophils were not able to ingest non-opsonized yeasts (eosinophils plus opsonized C. neoformans versus eosinophils plus non-opsonized C. neoformans, P < 0·05). C. neoformans phagocytosis was blocked by anti-FcγRII and anti-CD18 mAbs (Fig. 1b), suggesting that both receptors are involved in this phenomenon. Flow cytometric analysis of MHC class II surface expression demonstrated that the ingestion of opsonized yeasts

stimulated the increase of both the percentage and the mean fluorescence intensity (MFI) of MHC class II on eosinophils (Fig. 2a) (eosinophil plus opsonized C. neoformans versus eosinophil plus non-opsonized C. neoformans; P < 0·02). According to the observations for C. neoformans MAPK Inhibitor Library phagocytosis, MHC class II expression by eosinophils incubated with opsonized yeasts

was completely inhibited by FcγRII and CD18 (Fig. 2b). Furthermore, the increased expression of MHC class II on eosinophils treated with opsonized C. neoformans was significantly higher in cultures with GM-CSF than in its absence (60% versus 20%; P < 0·02) (Fig. 2b). We further analyzed selleck chemicals the expression of MHC class I, CD80 and CD86 on the surface of eosinophils incubated with opsonized or non-opsonized C. neoformans, in the presence or absence of GM-CSF. Figure 3a demonstrates that in the presence of GM-CSF, opsonized C. neoformans drastically increased the percentage and MFI of MHC class I expression on eosinophils (eosinophil plus opsonized C. neoformans versus eosinophil plus non-opsonized C. neoformans; P < 0·01). Moreover, opsonized C. neoformans significantly up-regulated the surface expression of CD80 and CD86 on these cells (eosinophil plus opsonized C. neoformans versus eosinophil plus non-opsonized C. neoformans; P < 0·05). Similar results were observed in cultures performed in the absence of GM-CSF (Fig. 3b). Therefore, in contrast to that observed for MHC class II, opsonized

C. neoformans up-regulated the expression of MHC class I and costimulatory molecules, regardless of the presence of GM-CSF Carnitine dehydrogenase in the medium. The levels of IFN-γ, TNF-α and IL-12p40 were also quantified in the supernatants of eosinophils obtained 24 hr after culture with opsonized or non-opsonized C. neoformans in the presence or absence of GM-CSF. Figure 4 shows the production of cytokines in cultures containing GM-CSF, revealing that in the presence of opsonized C. neoformans, eosinophils secreted significant amounts of IFN-γ, TNF-α and IL-12p40, compared to cells incubated in medium alone or with non-opsonized yeasts (P < 0·03). In contrast, Th2 cytokines (such as IL-4, IL-10 and IL-13) were not detected in these culture supernatants. Almost the same results were obtained in the absence of GM-CSF (data not shown). In order to evaluate the production of fungicidal molecules by GM-CSF-stimulated eosinophils incubated with opsonized C.

Louis, MO) diluted in dimethylsulphoxide plus

saline was

Louis, MO) diluted in dimethylsulphoxide plus

saline was injected intravenously into mice 6 hr before splenocyte harvest, and subjected to cell surface and intracellular cytokine staining as described.33,34 The CD8+ T-cell response to OVA257–264 was examined with H-2Kb dimer X (BD Biosciences, San Jose, CA) loaded with OVA257–264 peptide.30 Antibodies for cell surface and reagents for intracellular cytokine staining were purchased from BD Biosciences. For quantifying cytokine production by L. monocytogenes-specific T cells, splenocytes check details were plated into 96-well round bottom plates (5 × 106 cells/ml), and stimulated with the H-2Kb major histocompatibility complex (MHC) class I OVA257–264 or I-Ab MHC class II listeriolysin O (LLO)189–201 peptides (1 μm) in media supplemented with brefeldin BGB324 A (Golgi-plug reagent).30,31 The concentration of IFN-γ

in serum was quantified by enzyme-linked immunosorbent assay (R&D Systems, Minneapolis, MN). The differences in geometric mean CFUs, number and percentage of T cells between groups of mice were evaluated using the Student’s t-test with P < 0·05 taken as statistically significant (GraphPad Prism software, La Jolla, CA). Based on the potency whereby IL-21 controls the activation and differentiation of NK and T cells,1 and the protective roles for each of these cell types in innate L. monocytogenes host defence, the impact conferred by IL-21 deficiency on early susceptibility to L. monocytogenes infection was enumerated. After infection with 1 50% lethal dose (LD50; 105 CFUs in control B6 mice), both IL-21-deficient and control B6 mice each contained similar numbers

of recoverable L. monocytogenes CFUs within the first 72 hr after infection (Fig. 1a). Moreover by 72 hr post-infection, the remaining mice in each group uniformly became moribund. Therefore, no apparent defects in innate susceptibility based on the degree of bacterial proliferation and time to death were found for IL-21-deficient compared with control mice after high-dose L. monocytogenes infection. MYO10 In similar experiments, the susceptibility of IL-21-deficient mice was also enumerated after infection with reduced L. monocytogenes inocula (103 CFUs) to more precisely characterize the potential requirement for IL-21 in innate host defence. With this reduced L. monocytogenes inocula, IL-21-deficient and control mice both appeared healthy and did not become moribund. Furthermore, no significant differences in L. monocytogenes bacterial burden were identified for IL-21-deficient mice compared with control mice at each time-point within the first 7 days post-infection even with this reduced L. monocytogenes dose (Fig. 1b). In both groups of mice, the bacterial burden was sustained over the first 72 hr after infection, and then declined to levels that approached the limits of detection by day 5 post-infection.

“We examined two aspects of temperamental approach in earl

“We examined two aspects of temperamental approach in early infancy, positive reactivity and anger, and their unique and combined influences on maternal reports of child surgency and attention focusing at 4 years of age. One hundred and fourteen infants were observed for their positive reactions to novel stimuli at 4 months, and their anger expressions during arm restraint at 9 months. Child surgency and attention focusing at age 4 years were assessed by maternal report. Infants who expressed more anger to restraint were rated higher in surgency during early childhood relative to infants who expressed less anger. The effects of positive reactivity to novelty on attention focusing were moderated by anger to restraint. These findings

suggest that infant temperamental approach tendencies Ridaforolimus chemical structure are multifaceted and have both unique and combined influences on later maternal report of attention and social behavior. “

search for an object hidden by an occluder in the light months later than one hidden by darkness. One explanation attributes this décalage to easier action demands in darkness versus occlusion, whereas another attributes it to easier representation demands in darkness versus occlusion. However, search tasks typically confound these two types of demands. This article presents a search task that unconfounds them to better address these two explanations of the “dark advantage.” Objects were hidden by submersion in liquid instead of occlusion with a screen, allowing infants to search with equally simple actions in light versus dark. In Experiment 1, 6-month-olds Nutlin-3a mouse unexpectedly showed a dark disadvantage by discriminating when an object was hidden in the light but not the dark. Experiment 2 addressed the possibility that representation demands were higher in the dark than the light and showed that infants’ search in the dark increased to match that in the light, but not exceed it. Six-month-olds can thus search for a hidden Sulfite dehydrogenase object both when action demands are simplified and

when a noncohesive substance rather than a cohesive occluder hides the object, supporting aspects of both action-demand and representation-demand explanations of décalage in search behavior. “
“This study examines face-scanning behaviors of infants at 6, 9, and 12 months as they watched videos of a woman describing an object in front of her. The videos were created to vary information in the mouth (speaking vs. smiling) and the eyes (gazing into the camera vs. cueing the infant with head turn or gaze direction to an object being described). Infants tended to divide their attention between the eyes and the mouth, looking less at the eyes with age and more at the mouth than the eyes at 9 and 12 months. Attention to the mouth was greater on speaking trials than on smiling trials at all three ages, and this difference increased between 6 and 9 months. Despite consistent results within subjects, there was considerable variation between subjects.

e CD25+ cells) were depleted before activation (Fig  2a; compare

e. CD25+ cells) were depleted before activation (Fig. 2a; compare whole versus CD25-depleted populations on day 0). In contrast to control PBMC, depletion of CD25+ cells resulted in loss of CD4+ FoxP3HI cells at day 3 post-activation (Fig. 2a; selleck products compare whole versus CD25-depleted populations on day 3). Moreover, if carboxyfluorescein succinimidyl ester (CFSE)-labelled CD25Neg cells were reintroduced

into these polyclonally activated PBMC, there was significantly greater Teff proliferation in PBMC depleted of Tregs (Fig. 2b). Together, these data provide evidence to support the conclusion that aTregs derive from a starting pool of rTregs within PBMC. To study the effect of IFN-I on the generation of aTregs, freshly isolated PBMC were stimulated with anti-CD3 in the absence or presence of human leucocyte IFN (predominantly IFN-α) at 100 or 1000 U/ml or purified recombinant human IFN-β. Then, the total number of CD4 T cells and the generation of aTregs (CD4+ FoxP3HI IFN-γNeg)

and aTeffs (CD4+ FoxP3Low/Neg IFN-γPos) were analysed for separate normal donors after 3 days of polyclonal activation without or with added IFN-α (Fig. 3) or IFN-β (Fig. S1). While there was no consistent inhibitory or stimulatory effect of IFN-α on total CD4 cell numbers (Fig. 3a,b), there was an average of 42% (P = 0·03) and 50% (P = 0·005) inhibition of aTreg generation in the presence of 100 and 1000 U/ml of IFN-α, respectively (Fig. 3c,d). In contrast, the presence of IFN-α tended

to increased the number of aTeff cells with an average of 53% increase in the number of aTeff cells using 1000 Units IFN-α (P = 0·06) (Fig. 3e,f). In contrast, although IFN-β significantly suppressed Treg activation, this cytokine also tended to decrease Teff activation at the higher concentration (Fig. S1). Although the number of donor PBMC tested with IFN-β was limited, the results may suggest that IFNs α and β may exert distinct effects on lymphocyte homeostasis during cell activation. As a result of the opposite effects of IFN-α on aTreg and aTeff, there was an alteration in the balance Ergoloid between regulatory and effector cells as represented by the aTreg:aTeff ratio. Across all seven donors, this balance tended to favour aTregs in the absence of IFN-α (average aTreg:aTeff ratio = 1·4). However, the substantial suppression of aTreg generation induced by IFN-α caused a statistically significant shift in the mean aTreg:aTeff ratio for all seven donors [ratio = 0·7 for 100 U IFN-α (P = 0·05) and 0·5 for 1000 U IFN-α (P = 0·01)] such that aTeffs outnumbered aTregs on average by 2:1. Together, these data suggest that IFN-α significantly suppresses generation of activated Tregs in polyclonally activated PBMC, and at the same time promotes an increase in IFNγ-producing aTeffs.

aeruginosa mucA only weakly associated with S aureus (Fig 2, se

aeruginosa mucA only weakly associated with S. aureus (Fig. 2, second row). Small S. aureus microcolonies were found on the substratum of the flow chambers. comstat analysis showed that during the mixed-species biofilm formation, the mucA mutant was much more abundant than the S. aureus strains. The ratios of the total biomass of the mucA mutant to MN8, ISP479 and 15981 were 5.58 (± 0.99) : 1, 5.82 (± 2.16) : 1 and 5.72 (± 1.48) : 1, respectively. The mucA biofilms were highly similar with or without co-cultivation with S. aureus. We further studied co-culture biofilms

formed by the P. aeruginosa rpoN mutant with S. aureus MN8, ISP479 and 15981, respectively. In co-culture biofilms, the P. aeruginosa Apoptosis Compound Library rpoN mutant weakly associated with S. aureus and formed biofilms with loosely packed microcolony structures (Fig. 2, third row). There was very little S. aureus biomass embedded inside the microcolonies of rpoN mutant, and it seemed that S. aureus could not even colonize the substratum where no P. aeruginosa biofilm was located (Fig. 2, third row). These

results indicate that the P. aeruginosa rpoN mutant lacks components mediating S. aureus microcolony formation. comstat analysis showed that during the mixed-species biofilm formation, the rpoN mutant was much more abundant SB431542 than the S. aureus strains. The ratios of the total biomass of the rpoN mutant to MN8, ISP479 and 15981 were 100.29 (± 17.07) : 1, 95.86 (± check details 8.57) : 1 and 98.1 (± 14.1) : 1, respectively. The P. aeruginosa rpoN mutant is defective in the formation of flagellin and pilin (Ishimoto & Lory, 1989; Totten et al., 1990), which are the essential components for the synthesis of flagellum and type IV pilus, respectively. The P. aeruginosa cell

surface appendages flagella and pili and their mediated motilities were shown to be important factors for biofilm structure development (Klausen et al., 2003a, b; Barken et al., 2008). Moreover, the rpoN monospecies biofilm structures are similar to biofilm structures formed by the pilA mutant from our previous studies (Klausen et al., 2003b). We therefore examined the effects of P. aeruginosa type IV pili on microcolony formation in P. aeruginosa–S. aureus co-culture biofilms. Because we observed that there was no significant difference among the three tested S. aureus strains in both monospecies and mixed-species biofilms, we chose the MN8 strain for the subsequent biofilm studies. The P. aeruginosa pilA mutant, which is unable to produce type IV pili, was found to be unable to associate with S. aureus MN8 to form microcolonies in co-culture biofilms and tended to outcompete S. aureus MN8 (Fig. 3a). The ability of the P. aeruginosa pilA mutant to associate with S. aureus MN8 and form mixed-species microcolonies in co-culture biofilms could be restored by complementation in trans with the pilA gene on the pDA2 plasmid (Fig. 3b). To further examine the role of P.

Nonetheless, those changes in chromatin structure do not fully ex

Nonetheless, those changes in chromatin structure do not fully explain the changes of mRNA steady-state levels across the intra-erythrocytic cycle, with the exception of ring stage- or exo-erythrocytic-specific genes (13,14). Such observations are consistent BGB324 order with recent data, demonstrating that mRNA steady-state

levels and transcription rate do not correlate for about half of the parasite’s genes (86). In that case, genes could be massively transcribed at the trophozoite stage followed by major regulations at the post-transcriptional level. This hypothesis finds support in the fact that the parasite’s preinitiation complex interacts with both stage-specific ‘active’ and ‘inactive’ promoters (87) and that mRNA decay rates are significantly lengthened during the intra-erythrocytic cycle suggesting major post-transcriptional regulations (65). To further BAY 57-1293 complement these data, Bartfai et al. used

a ChIP-seq approach to show that, unlike in other eukaryotes, the histone H2A variant H2A.z is a constant and ubiquitous feature of all intergenic regions throughout the parasite erythrocytic cycle (7). As H2A.z is usually involved in chromatin destabilization and active transcription in eukaryotes (88–90), these results are consistent with a transcriptionally permissive state of P. falciparum’s chromatin during the asexual cycle. In addition, previous

mass spectrometry studies showed that, unlike the abundant and more variable canonical histones, H2A.z is present at low and constant level throughout the parasite’s cycle (33,38). This observation, combined with the high sensitivity of H2A.z to MNase digestion Fenbendazole (88,89), is consistent with the relative nucleosome depletion that was observed by MAINE-seq and ChIP-on-chip in noncoding regions of the genome (6,52). Given the low levels of H2A.z and its extreme sensitivity to MNase digestion, H2A.z-containing nucleosomes can mostly be detected by targeted and specific immunoprecipitation-based sample enrichments. Quantitative measurements in such experiments, however, imply a careful normalization of histone variant levels vs. canonical histones. All together, these data confirm an unusual parasite chromatin structure and speculate an active transcriptional state during most of the erythrocytic cycle with a few exceptions such as clonally variant genes as well as genes known to be essential to early erythrocytic and sexual stage differentiation. It is therefore possible that part of transcriptional regulation in P. falciparum could occur during elongation rather than initiation. This hypothesis is supported by the recent observation that H2A.z seems to facilitate the passage of the RNA polymerase II (90).