This technique is by far the most successful NGS method to sequence the P. falciparum genome. Many variations of the technique Palbociclib in vivo were

developed specifically for the sequencing of the (A + T)-rich genome of the malaria parasite (6–8) (Figure 1). Over the last couple of years only, many studies have used Illumina®’s NGS technology to identify SNPs and other mutations linked to drug resistance in the murine malaria parasite P. chabaudi (9,10) and the human malaria parasite P. vivax (11). Other analyses have contributed to the characterization of the P. falciparum transcriptome with the discovery of new splicing events (12–14) and transcription start sites (15). Finally, Illumina®’s NGS technology was used to discover atypical features of P. falciparum’s chromatin (6,16)

and various epigenetic events (7). Currently, the future of high-throughput selleck inhibitor sequencing seems to be leaning towards single-cell sequencing applications. Going further, third-generation sequencing (TGS) technologies propose to use single molecules as direct templates for sequencing (techniques so far under development at Helicos Biosciences and Pacific Biosciences). These TGS technologies should simplify the sample preparation procedure, avoid the bias introduce by DNA amplification and library preparation and be even more affordable than their predecessors. Nevertheless, the power of high-throughput Tolmetin sequencing also represents one of the major pitfalls for the analysts.

The high-throughput and depth of quantitative measurements produced by NGS and TGS technologies come at the cost of producing sophisticated algorithms and software tools capable of accurately examining millions to billions of reads. The data generated by these methods are complex, novel and abundant. The computational and statistical analysis of raw outputs is the tricky step where incorrect normalization and processing can yield misleading conclusions. Novel methods of quantitative analysis are constantly under development and testing. There is yet no consensus on which analytical approach is the most accurate, particularly for the Plasmodium genome. The avalanche of whole-genome data over the past few years generated an immense source of knowledge that still requires maturing and processing. Nevertheless, in the near future, these powerful genomic approaches will certainly catalyse the transformation of this biological knowledge into viable therapeutic strategies. Single-cell sequencing will accelerate the genotyping of strains in patients’ blood sample or other field isolates. Comparative genomics then will be an important source of information regarding the evolution and dynamics of malaria parasites’ populations. Ultimately, such knowledge could be used for accurate diagnosis and targeted treatment of patients.

It is also well established that there is a direct relationship between high viral loads and transmission

probability.[67] Despite this relationship, as indicated above, 75% of infections are by a single variant.[68] Hence, the challenge for blocking of acquisition immunologically becomes one of inhibiting productive infection of a small number of cells by a small number of virions at local mucosal sites within the first 3 days following exposure. Passive immunization studies in NHPs have established unequivocally that neutralization is a key mechanism of protection against infection with model AIDS viruses such as SHIV162p3.[16, 69] By contrast, the role of Fc-mediated effector function in blocking acquisition is indirect and more controversial.[70, 71] Two seminal passive immunization studies in NHPs employing the neutralizing monoclonal antibody (mAb), b12, point toward check details a role of Fc-mediated effector function in protection against both high-dose[70] and low-dose[71] vaginal challenges with SHIV162p3. Groups received either wild-type b12 capable of both neutralization and Fc-mediated effector function

or b12-LALA, in which Fc-mediated effector function, but not neutralization, was abrogated by L to A mutations at residues 234 and 235 in the CH2 domain of IgG1 (b12-LALA). In both models, protection against SHIV162p3 decreased by approximately 50% for b12-LALA. These are learn more the only passive immunization studies to date unambiguously indicating a role of Fc-mediated effector function in blocking acquisition. The contributing effector function is not known because b12-LALA is incapable of ADCC, ADCVI and phagocytosis. Further, b12 variants with improved Fc receptor binding and biological function did not increase protection in this model, although vaginal mAb levels

might not have been optimal to reveal enhanced protection at the times of challenge.[72] Hence the precise role of Fc-mediated effector function in blocking acquisition Calpain in this model is unknown. There is no evidence that passive immunization with non-neutralizing mAbs can block acquisition by Fc-mediated effector function. By contrast, a recent study suggested that passive immunization using non-neutralizing antibodies with potent Fc-mediated effector function can increase post-infection control of viraemia.[17] That study reported statistically significant post-infection control against a vaginal challenge with SHIV162p3 using a mixture of two non-neutralizing anti-gp41 mAbs specific for its principal immunodominant domain.[17] These mAbs were vetted by an algorithm assigning weights based on their abilities to neutralize, mediate ADCC, block infection of monocyte-derived macrophages, bind Fc receptors on cell surfaces and capture free virions.

1; Nikon). The light source was a 488 nm solid-state laser (Sapphire 488-30; Coherent, Dieburg, Germany). Between 2 × 105 and 5 × 105 CHO cells were seeded on glass cover slips 2–3 days before the experiments. lambrolizumab Immediately before Ca2+ imaging, the cells were incubated with the particular concentration of fusion proteins in 50 μl culture medium and washed afterwards with culture medium with 10 mm HEPES added. Glass cover slips were mounted on the stage of an Olympus IX 70 microscope equipped with a 20 × (UApo/340, N.A. 0·75) objective in a self-made

recording chamber, which allowed a complete solution exchange < 1 second. In parallel, T cells were loaded at 22–23° for 30 min with 2 μm fura-2/acetoxymethyl ester (AM) (Invitrogen) in culture medium with 10 mm HEPES added, washed with fresh medium, and immediately used. T cells

were then added and cells were alternately illuminated at 340 and 380 nm with the Polychrome IV monochromator (TILL Photonics, Gräfelfing, Germany) and with an infrared light source using SP 410 as excitation filter and DCLP 410 as dichroic mirror. The fluorescence emissions at λ > 440 nm (LP 440) were captured with Selleck Palbociclib a CCD camera (TILL Imago), digitized, and analysed using TILL Vision software. Ratio images were recorded at intervals of 5 seconds. In some experiments thapsigargin (TG, 1 μm) was used to completely empty the stores. Excel, Igor Pro and TILL Vision were used for data analysis. An unpaired, two-sided Students t-test was used to test for significance. All fusion proteins were generated as single chain molecules to prevent any false pairing or degradation (Fig. S1). The extracellular domains of CD80 and CD86 were cloned at the N-terminal end of the scFv anti-CD33 to ensure correct binding to their respective receptors.52

Soluble proteins were produced in HEK-293 cells by transient gene expression with a yield of 0·5–2 mg total protein/l of cell culture supernatant, purified by IMAC and checked by Coomassie and Western blot analysis for purity and integrity. Proper binding for all fusion proteins was tested by enzyme-linked immunosorbent assay on recombinant CD33 antigen (data not shown) and flow cytometry PAK5 (Fig. S2) on either CD33-transfected CHO or Jurkat T cells. Binding of the scFv anti-CD33 was not altered in any of the fusion proteins when compared with the parental scFv anti-CD33. The scFv anti-CD3 and the extracellular domains of CD80 and CD86 showed a moderate to weak binding affinity to their respective receptors. The dscFv anti-CD3/anti-CD19 were used as control. The dscFv anti-CD33/anti-CD3 construct induced proliferation of naïve T cells in the presence of the CD33 antigen in a dose-dependent manner (Fig. 1).

Any therapeutic manipulation aimed at improving viral control by reducing Blimp-1 expression has to avoid the point at which further reduction of Blimp-1 becomes harmful. D.T.F. & J.E.D.T. are funded by the

Wellcome Trust. The authors declare no financial or commercial conflict of interest. “
“Dipeptidyl peptidase 2 (DPP2) is an N-terminal dipeptidase, required for maintaining lymphocytes in a resting state. Mutant mice with T-cell-specific GSK-3 inhibitor knock-down (kd) of DPP2 (lck-DPP2 kd) were generated and analyzed for their phenotype. Normal thymocyte development and a modest increase in the proportions of peripheral T cells were observed in these mice compared with littermate controls. Interestingly, the peripheral T cells were hyperactive upon TCR stimulation in vitro, although they did not express any activation markers. Furthermore, CD3-crosslinking in the naïve CD4+ and CD8+ T cells of lck-DPP2 kd mice resulted mainly in IL-17 production. Similarly, the mutant T cells secreted primarily

IL-17 after in vivo priming and in vitro antigen-specific restimulation. These data suggest that IL-17 production is the default program for T-cell differentiation in the Dabrafenib absence of DPP2. Thus, DPP2 seems to impose a threshold for quiescent T cells, preventing them from drifting into cell cycle. Dipeptidyl peptidase 2 (DPP2), a member of the serine dipeptidyl peptidase family, is an N-terminal protease that is ubiquitously transcribed in most tissues 1. It is localized in intracellular vesicles and is also secreted upon cellular activation 2. The DPP2 expression level is particularly high in quiescent T cells and fibroblasts, but is significantly downregulated upon activation of these cells 3. We previously demonstrated that DPP2 inhibition in vitro causes apoptosis in quiescent, but not activated, T cells 4 and fibroblasts due to a deregulated entry into the cell cycle 5. In order to analyze the role of DPP2 in quiescent T lymphocytes in vivo, we generated mutant mice where DPP2 is specifically downregulated

in the T-cell lineage. The majority of T cells in the body are in a resting state until encounter with a pathogen. In the presence of exogenous cytokines, TCR-stimulation of naïve CD4+ and CD8+ T cells GNA12 leads to their maturation into various TH cell subsets and CTL effector cells. CD4+ cells can differentiate into the classical Th1 or Th2 subsets 6 or one of the more recently discovered lineages, Th17 7 and inducible Tregs 8. Differentiation into Th1 and Th2 cells depends on exogenous IL-12 and IL-4, respectively. In contrast, Th17 differentiation can be achieved with TGF-β and IL-6, two cytokines with opposing effects, while TGF-β alone induces iTregs 8. Ghoreschi et al. recently demonstrated that IL-1 and/or TGF-β in conjuction with IL-6, IL-21 and IL-23 promote Th17 development 9. Thus, the cytokine environment determines TH effector differentiation, a mechanism mediated through selective STAT proteins 10, 11.

However, the increased difference in migratory rates of Treg and non-Treg in the presence of a MBMEC layer hints to Treg-specific interactions with the endothelial CSF-1R inhibitor cell layer, either due to direct cell–cell contact or due to a constitutive secretion

of soluble factors by the endothelial cells. CCL20 as a soluble stimulus secreted by the MBMEC layer can be excluded since its expression is only found in epithelial cells of the choroid plexus and astrocytes during EAE relapse 20, 21 but not in brain endothelium. More likely, Treg seem to have an advantage in forming stable cell–cell contacts with the brain endothelium, consistent with their higher expression of LFA-1 and CD49d, as they intensively accumulated in or on top of the endothelial cell monolayer compared to their non-regulatory counterparts. The preferential migration of Treg through a porous membrane in the presence of the chemoattractant CCL20 was expected by their CCR6 cell surface expression MI-503 solubility dmso and was maintained when T cells migrated across an in vitro model of the BBB. In the non-regulatory fraction,

particularly the Th17 cells should be attracted by the CCL20 gradient as they are known to express high amounts of CCR6 compared to other effector cell types 22. This finding further supports the current notion that CCR6 expressing, autoreactive effector Th17 cells may be able to gain entry to the yet non-inflamed CNS, facilitated through CCL20 secretion by epithelial cells of the choroid plexus or brain resident glia cells 21, 23, 24, and induce the subsequent immune responses by producing CCL20 among other inflammatory stimuli 22. In consequence, this might

lead to inflammation of the BBB endothelium allowing further, CCL20 independent lymphocyte infiltration into the CNS parenchyma. Treg, exhibiting a stronger migratory response to CCL20 than conventional CD4+ T cells, should therefore PD184352 (CI-1040) have a higher prevalence in the brain tissue compared to their effector counterparts under healthy conditions, consistent with our in vivo finding. Human Treg have been reported to be present in the CNS in certain neurological disorders, such as gliomas 25, 26. Under conditions of experimental autoimmune neuroinflammation as in EAE, Treg accumulate in the murine CNS 4, 10, most notably in the remission phases 11, counterbalancing encephalitogenic CNS responses. As mentioned above, data on the presence and function of Treg in the human CNS are sparse 12–14, 18. To translate our findings into human pathophysiology, we used an in vitro model of the human BBB to mimic lymphocyte diapedesis in vivo. In contrast to HD, MS patient-derived Treg failed to outmatch their non-regulatory counterparts in crossing the BBB under basal, non-inflammatory conditions.

1). We found that 104 was the optimal number of pmel-1 spleen cells that could be mixed with 107 WT spleen cells. Compared with WT spleen cells, donor spleen cells from IL-15 KO mice has a significantly less suppressive effect on the primary response of pmel-1 T cells to peptide-pulsed Doxorubicin DC than spleen cells from WT mice (Supporting Information Fig. 2).

The suppression mediated by co-transfer of WT spleen cells was even more dramatic when the secondary response of pmel-1 T cells to DC vaccination was measured. Surprisingly, the co-transfer of spleen cells from IL-15 KO mice did not suppress but increased the secondary response of pmel-1 T cells. IL-15 KO mice are known to have deficient numbers of CD122+CD8+ memory-like PI3K Inhibitor Library research buy (sometimes referred to as “memory-phenotype” or “innate”) T cells, NK, and NKT cells, but have sufficient numbers of CD25+CD4+ Treg (see review 11, and Supporting Information Fig. 2), suggesting that lymphocytes other than CD25+CD4+ Treg played the key suppressive role in our model. Consistent with this notion, CD122+CD8+ memory-like cells constituted the major population of lymphocytes that underwent lymphopenia-driven proliferation when adoptively transferred into sub-lethally irradiated mice (Supporting Information

Fig. 3). To substantiate our initial observations and determine the effect of CD122 depletion on the therapeutic efficacy of adoptive T-cell therapy in lymphopenic

mice, we treated mice bearing Sclareol 6-day subcutaneous F10 tumors with irradiation, followed by adoptive transfer of 104 pmel-1 spleen cells and 107 congenic spleen cells with or without prior depletion of CD122+ cells, and vaccination with peptide-pulsed DC. The absolute numbers of pmel-1, congenic, and host T cells in the blood were enumerated at different intervals after vaccination. We found that depletion of CD122+ cells doubled the number of pmel-1 T cells found in the blood of vaccinated mice 2 wk after vaccination (Fig. 1A), and there was no recovery of congenic T cells when CD122+ cells were depleted (Fig. 1B). CD122+ lymphocytes rather than CD122− cells were the primary lymphocyte subpopulation that underwent lymphopenia-driven proliferation. In contrast, host T-cell recovery, which is reflected by the thymic output of naïve T cells, did not differ in recipients of CD122-depleted and non-depleted T cells. Most importantly, depletion of CD122+ lymphocytes resulted in a greater antitumor efficacy (Fig. 1C and D). Depletion of CD122+ cells from congenic donor spleen cells led to a significantly longer delay of tumor growth and an increase in median survival of tumor-bearing mice (from 38 days to 58 days).

The plasma separation columns seem to trigger

the formation of proinflammatory complement factors including C3a and C5a, while the Adriamycin clinical trial same anaphylatoxins are adsorbed by the LDL apheresis columns, however, to varying degree. Proinflammatory cytokines are to some extent adsorbed by the LDL apheresis columns, while some of the anti-inflammatory cytokines increase during treatment. Finally, we discuss the effect of apheresis on different biomarkers including C-reactive protein, fibrinogen, adhesion molecules, myeloperoxidase and HDL cholesterol. In conclusion, even if there are differences between pro- and anti-inflammatory biomarkers during LDL apheresis, the consequences for the patients are largely unknown and larger studies need to be performed. Preferably, they should be comparing the effect of different LDL apheresis columns MK 2206 on the total inflammatory profile, and this should be related to clinical endpoints. Patients with familial hypercholesterolemia (FH) carry a high risk of premature atherosclerosis if not adequately treated [1], owing to high levels of low-density lipoprotein (LDL) cholesterol. In most instances, LDL cholesterol can be reduced by means

of HMG-CoA reductase inhibitors (statins). However, for some patients, the medication is not effective or the patients do not tolerate the medication owing to side effects. In these instances, extracorporeal treatment with LDL apheresis effectively lowers

LDL cholesterol and clinical endpoints [2–4]. Extracorporeal treatment, however, is hampered by blood–biomaterial interaction that in turn may trigger inflammatory responses. These responses may be both pro- and anti-inflammatory, and the net result of these reactions is important to the patient [5]. Thus, measures to attenuate the inflammatory responses elicited by the extracorporeal treatment should be taken to obtain optimal biocompatibility. FH is an autosomal dominant inherited disease leading to high levels of LDL cholesterol and increased risk of premature atherosclerotic disease. The landmark studies Rucaparib in vivo by Brown and Goldstein firmly documented the link between familial hypercholesterolemia and the structure of the LDL-receptor [6–10]. The prevailing form is heterozygous (heFH) in which approximately 50% of the LDL-receptors are missing. Other forms of familial hypercholesterolemia have since been discovered [11–14]. heFH is quite common; most studies indicate a prevalence of 1/500 in white Caucasians [15]. The increased risk for atherosclerotic diseases in FH [1, 16] is reduced when patients are treated with statins [17–19]. FH homozygotes (hoFH) are rare (1/1000 000) and often develop atherosclerotic complications early [15], even if new register data show a survival benefit of modern lipid-lowering therapy [20]. Thus, there is general consensus that reduction in LDL cholesterol is mandatory in FH [21–23].

14,20 In many HIV-infected

women, the plasma viral load (PVL) has not been found to correlate with genital tract viral load (GTVL) and has also been found to be genetically distinct.21–23 Genital tract viral shedding can be highly localized and can change with the menstrual cycle (S. Cu-Uvin, unpublished data,24,25). In addition, the proportion of virus in the genital tract that is actually infectious and capable of transmission seems to be very low, irrespective of the PVL and the GTVL (M. Ghosh and J. V. Fahey, unpublished data;26,27). In a study by Keller et al.,14 the CVL was collected from normal women throughout the course of the menstrual cycle and assayed for a number of immune activators, antimicrobials and antibodies. CVL samples were found BVD-523 concentration to contain a spectrum of factors, most of which changed with the menstrual cycle, specifically dipping

at mid-cycle to the early secretory phase, which has been proposed as a ‘window of vulnerability’ through which women become infected with HIV.28 Many of the innate immune molecules that are known to protect the FRT18,19,29 are regulated by the sex find more hormones oestradiol and progesterone during the menstrual cycle.30–32 Two such molecules are the anti-proteases secretory leucocyte protease inhibitor (SLPI) and Trappin-2/Elafin. SLPI and Trappin-2/Elafin are members of the whey acidic protein (WAP) family. They are produced by multiple cell types, secreted in mucosal secretions constitutively and can be elevated in the presence of inflammatory stimuli.33–37 These molecules are anti-inflammatory; they function by inhibiting specific neutrophil proteases. Trappin-2/Elafin has been demonstrated to inhibit neutrophil Thalidomide elastase and proteinase 3.19 In addition, both SLPI and Trappin-2/Elafin have been demonstrated to have antimicrobial activity.38–41 The main mechanism for this activity is predicted to be the cationic nature of these molecules, which destabilizes the negative charges of the bacterial cell wall or the viral envelope.40,41 Trappin-2/Elafin

has specifically been shown to have antimicrobial activity against both Gram-positive and Gram-negative bacteria, and fungi.39 Trappin-2/Elafin is unique in that it can be biologically active as both cell-associated and secreted protein. The precursor of Trappin-2/Elafin is known as Trappin-2, which contains a transglutaminase substrate-binding domain (TSBD) that is cleaved from the processed Trappin-2/Elafin molecule. The TSBD is involved in covalent binding to extracellular matrix proteins, including laminin, fibronectin, collagen IV, elastin and fibrinogen.33,40 This might provide local protection from proteolytic activity by endogenous proteases, whereas the cleaved soluble form can act at distant sites. Trappin-2/Elafin has been found to be involved in immune disorders of the skin, such as psoriasis42 and lung chronic obstructive pulmonary disorder (COPD43).

An Improved and Reliable Method for Isolation of Microvascular Endothelial Cells from Human Omentum. Microcirculation18(8), 635–645. Objectives:  Despite an increasing research demand for human microvascular endothelial

NVP-AUY922 cells, isolation of primary endothelial cells from human tissue remains difficult. The omentum, a highly vascular visceral adipose tissue, could provide an excellent source of these cells. Methods:  A reliable method to isolate HOMECs has been developed. It consists of initial enzymatic digestion (to deplete cell contaminants), followed by further digestion, selective filtration, and immunoselection using Dynabeads coated with CD31 antibody. Cultures were characterized for expression of endothelial PF-02341066 price cell markers

and their ability to undergo VEGF-dependent in vitro tube structure formation. Results:  Omental-derived cultures of microvascular endothelial cells were achieved with <5% contamination of other cell types. The endothelial origin of cells was confirmed by the constitutive expression of a range of vascular endothelial markers (CD31, CD105, vWF) and internalization of DiI-AcLDL. Furthermore, cultures were negative for lymphatic endothelial markers, underwent in vitro angiogenesis, and exhibited typical endothelial morphology. Conclusions:  This isolation method produces homogeneous HOMEC cultures that can be maintained in vitro for at least six passages without loss of cellular features characterizing endothelial cells. "
“Microcirculation (2010) 17, 47–58. doi: 10.1111/j.1549-8719.2009.00003.x Genetic familial hypercholesterolemia (FH) and combined hyperlipidemia (FCH) are characterized by elevated plasma low-density lipoprotein (LDL) (FH) and LDL/triglycerides (FCH), with mouse models represented by LDL receptor (LDLR) and apolipoprotein E (ApoE) gene deletion mice, respectively. Given the impact of FH and FCH on health outcomes, we determined the impact of FH/FCH on vascular structure in LDLR and ApoE mice. LDLR, ApoE and control

mice were utilized at 12–13 and 22–23 weeks when gracilis arteries were studied for wall mechanics and gastrocnemius muscles were harvested for microvessel density measurements. Conduit arteries and plasma samples were harvested TCL for biochemical analyses. Arteries from ApoE and LDLR exhibited blunted expansion versus control, reduced distensibility and left-shifted stress versus strain relation (LDLR > ApoE). Microvessel density was reduced in ApoE and LDLR (ApoE > LDLR). Secondary analyses suggested that wall remodeling in LDLR was associated with cholesterol and MCP-1, while rarefaction in ApoE was associated with tumor necrosis factors-α, triglycerides and vascular production of TxA2. Remodeling in ApoE and LDLR appears distinct; as that in LDLR is preferential for vascular walls, while that for ApoE is stronger for rarefaction.

[10] The discovery that the mechanism of action of FTY720 occurs via S1PR modulation[11] spurred interest in immunological functions of S1P signalling. Later studies demonstrated amelioration of experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis, with low-dose FTY720,[12] which has since been approved as a first-line oral agent for treatment of relapsing–remitting multiple sclerosis.[13-15] The pharmacology and biology of FTY720 are covered in great depth by other reviews.[16, 17] Studies to characterize the mechanisms underlying the induction of lymphopenia by FTY720 paved the

way to better B-Raf inhibitor drug understanding of the basic biological principles of lymphocyte circulation and revealed the importance of S1P1 in this process[4] (Fig. 1a). Using fetal liver from S1pr1−/− embryos to create bone marrow chimeric mice, Matloubian, et al. demonstrated that egress of lymphocytes from thymus and secondary lymphoid organs did not occur in the absence of S1P signalling, establishing

a requirement for S1P–S1P1 interaction in regulating lymphocyte egress. Additional HM781-36B studies established that S1P1 expression was temporally regulated during T-cell development, culminating in high expression by mature single-positive CD4 or CD8 thymocytes and that conditional deletion of S1pr1 in T cells alone was sufficient to block their egress from the thymus. As S1P1 provides a critical chemotactic cue, and levels of S1P are high in the blood and lymph and low in most tissues,[7] it was postulated that this

‘S1P gradient’ would play a role in lymphocyte egress. Indeed, disruption of the S1P gradient by 2-acetyl-4-tetrahydroxyimidazole, an inhibitor of the S1P degradative enzyme S1P lyase, led to lymphopenia and blocked T-cell egress from the thymus.[18] This effect was mediated by increases in tissue concentrations of S1P and S1P-mediated down-regulation of surface S1P1, so impairing chemotactic responses.[18] Studies using conditional deletion of the S1P biosynthetic enzymes, sphingosine kinases 1 and 2 (Sphk1/2) demonstrated that an almost complete loss of S1P in the blood and lymph correlated with high cell surface expression Non-specific serine/threonine protein kinase of S1P1 on naive T cells in the circulation. Lymphopenia was also evident, but infusion of S1P (in the form of S1P-producing erythrocytes) into sphingosine kinase-deficient mice, led to the release of lymphocytes into the blood concomitant with decreased cell surface expression of S1P1.[19] Mutant mice that express an internalization-defective S1P1 that is signalling competent have delayed lymphopenia kinetics in response to FTY720 or 2-acetyl-4-tetrahydroxyimidazole treatment, further supporting the premise that cell surface residency of S1P1 is a primary determinant of lymphocyte egress.[20] These observations combine to create a model whereby high concentrations of ligand lead to S1P1 surface down-regulation and so to non-responsiveness to S1P chemotactic cues.