Cardiac dysfunction and impaired compensatory response to pressure overload in mice deficient in stem cell antigen-1.

Stem cell antigen-1 (Sca-1) has been used to identify cardiac stem cells in the mouse heart. To investigate the function of Sca-1 in aging and during the cardiac adaptation to stress, we used Sca-1-deficient mice. These mice developed dilated cardiomyopathy [end-diastolic left ventricular diameter at 18 wk of age: wild-type (WT) mice, 4.2 mm ± 0.3; Sca-1-knockout (Sca-1-KO) mice, 4.6 mm ± 0.1; ejection fraction: WT mice, 51.1 ± 2.7%; Sca-1-KO mice, 42.9 ± 2.7%]. Furthermore, the hearts of mice lacking Sca-1 demonstrated exacerbated susceptibility to pressure overload [ejection fraction after transaortic constriction (TAC): WT mice, 43.5 ± 3.2%; Sca-1-KO mice, 30.8% ± 4.0] and increased apoptosis, as shown by the 2.5-fold increase in TUNEL(+) cells in Sca-1-deficient hearts under stress. Sca-1 deficiency affected primarily the nonmyocyte cell fraction. Indeed, the number of Nkx2.5(+) nonmyocyte cells, which represent a population of cardiac precursor cells (CPCs), was 2-fold smaller in Sca-1 deficient neonatal hearts. In vitro, the ability of CPCs to differentiate into cardiomyocytes was not affected by Sca-1 deletion. In contrast, these cells demonstrated unrestricted differentiation into cardiomyocytes. Interestingly, proliferation of cardiac nonmyocyte cells in response to stress, as judged by BrdU incorporation, was higher in mice lacking Sca-1 (percentages of BrdU(+) cells in the heart after TAC: WT mice, 4.4 ± 2.1%; Sca-1-KO mice, 19.3 ± 4.2%). These data demonstrate the crucial role of Sca-1 in the maintenance of cardiac integrity and suggest that Sca-1 restrains spontaneous differentiation in the precursor population. The absence of Sca-1 results in uncontrolled precursor recruitment, exhaustion of the precursor pool, and cardiac dysfunction.

HLA-Bw4 identifies a population of HIV-infected patients with an increased capacity to control viral replication after structured treatment interruption.

OBJECTIVES: After structured treatment interruption (STI) of treatment for HIV-1, a fraction of patients maintain suppressed viral loads. Prospective identification of such patients might improve HIV-1 treatment, if selected patients are offered STI. METHODS: We analysed the effect of previously identified genetic modulators of HIV-1 disease progression on patients' ability to suppress viral replication after STI. Polymorphisms in the genes killer cell immunoglobulin-like receptor 3DLI (KIR3DL1)/KIR3DS1, human leucocyte antigen B (HLA-B) and HLA Complex P5 (HCP5), and a polymorphism affecting HLA-C surface expression were analysed in 130 Swiss HIV Cohort Study patients undergoing STI. Genotypes were correlated with viral load levels after STI. RESULTS: We observed a statistically significant reduction in viral load after STI in carriers of HLA-B alleles containing either the Bw480Thr or the Bw480Ile epitope (mean adjusted effect on post-STI viral load: -0.82 log HIV-1 RNA copies/ml, P < 0.001; and -1.12 log copies/ml, P < 0.001, respectively). No significant effects were detected for the other polymorphisms analysed. The likelihood of being able to control HIV-1 replication using a prespecified cut-off (viral load increase < 1000 copies/ml) increased from 39% in Bw4-negative patients to 53% in patients carrying Bw4-80Thr, and to 65% in patients carrying Bw4-80Ile (P = 0.02). CONCLUSIONS: These data establish a significant impact of HLA-Bw4 on the control of viral replication after STI.

Reduced ejection fraction after myocardial infarction: is it sufficient to justify implantation of a defibrillator?

BACKGROUND: Improved survival after prophylactic implantation of a defibrillator in patients with reduced left ventricular ejection fraction (EF) after myocardial infarction (MI) has been demonstrated in patients who experienced remote MIs in the 1990s. The absolute survival benefit conferred by this recommended strategy must be related to the current risk of arrhythmic death, which is evolving. This study evaluates the mortality rate in survivors of MI with impaired left ventricular function and its relation to pre-hospital discharge baseline characteristics. METHODS: The clinical records of patients who had sustained an acute MI between 1999 and 2000 and had been discharged from the hospital with an EF of < or = 40% were included. Baseline characteristics, drug prescriptions, and invasive procedures were recorded. Bivariate and multivariate analyses were performed using a primary end point of total mortality. RESULTS: One hundred sixty-five patients were included. During a median follow-up period of 30 months (interquartile range, 22 to 36 months) 18 patients died. The 1-year and 2-year mortality rates were 6.7% and 8.6%, respectively. Variables reflecting coronary artery disease and its management (ie, prior MI, acute reperfusion, and complete revascularization) had a greater impact on mortality than variables reflecting mechanical dysfunction (ie, EF and Killip class). CONCLUSIONS: The mortality rate among survivors of MIs with reduced EF was substantially lower than that reported in the 1990s. The strong decrease in the arrhythmic risk implies a proportional increase in the number of patients needed to treat with a prophylactic defibrillator to prevent one adverse event. The risk of an event may even be sufficiently low to limit the detectable benefit of defibrillators in patients with the prognostic features identified in our study. This argues for additional risk stratification prior to the prophylactic implantation of a defibrillator.

Human invariant V alpha 24-J alpha Q TCR supports the development of CD1d-dependent NK1.1+ and NK1.1- T cells in transgenic mice.

A sizable fraction of T cells expressing the NK cell marker NK1.1 (NKT cells) bear a very conserved TCR, characterized by homologous invariant (inv.) TCR V alpha 24-J alpha Q and V alpha 14-J alpha 18 rearrangements in humans and mice, respectively, and are thus defined as inv. NKT cells. Because human inv. NKT cells recognize mouse CD1d in vitro, we wondered whether a human inv. V alpha 24 TCR could be selected in vivo by mouse ligands presented by CD1d, thereby supporting the development of inv. NKT cells in mice. Therefore, we generated transgenic (Tg) mice expressing the human inv. V alpha 24-J alpha Q TCR chain in all T cells. The expression of the human inv. V alpha 24 TCR in TCR C alpha(-/-) mice indeed rescues the development of inv. NKT cells, which home preferentially to the liver and respond to the CD1d-restricted ligand alpha-galactosylceramide (alpha-GalCer). However, unlike inv. NKT cells from non-Tg mice, the majority of NKT cells in V alpha 24 Tg mice display a double-negative phenotype, as well as a significant increase in TCR V beta 7 and a corresponding decrease in TCR V beta 8.2 use. Despite the forced expression of the human CD1d-restricted TCR in C alpha(-/-) mice, staining with mCD1d-alpha-GalCer tetramers reveals that the absolute numbers of peripheral CD1d-dependent T lymphocytes increase at most by 2-fold. This increase is accounted for mainly by an increased fraction of NK1.1(-) T cells that bind CD1d-alpha-GalCer tetramers. These findings indicate that human inv. V alpha 24 TCR supports the development of CD1d-dependent lymphocytes in mice, and argue for a tight homeostatic control on the total number of inv. NKT cells. Thus, human inv. V alpha 24 TCR-expressing mice are a valuable model to study different aspects of the inv. NKT cell subset.

Reduction in the expression of glucose transporter protein GLUT 2 in preneoplastic and neoplastic hepatic lesions and reexpression of GLUT 1 in late stages of hepatocarcinogenesis.

Expression of two important glucose transporter proteins, GLUT 2 (which is the typical glucose transporter in hepatocytes of adult liver) and the erythroid/brain type glucose transporter GLUT 1 (representing the typical glucose transporter in fetal liver parenchyma), was studied immunocytochemically during hepatocarcinogenesis in rats at different time points between 7 and 65 wk after cessation of 7-wk administration of 12 mg/kg of body weight of N-nitrosomorpholine p.o. (stop model). Foci of altered hepatocytes excessively storing glycogen (GSF) and mixed cell foci (MCF) composed of both glycogenotic and glycogen-poor cells were present at all time points studied. Seven wk after withdrawal of the carcinogen, GSF were the predominant type of focus of altered hepatocytes. Morphometrical evaluation of the focal lesions revealed that the number and volume fraction of GSF increased steadily until Wk 65. MCF were rare at 7 wk, increased slightly in number and size until Wk 37, but showed a pronounced elevation in their number and volume fraction from Wk 37 to Wk 65. In both GSF and MCF, GLUT 2 was generally decreased or partially absent at all time points. Consequently, foci of decreased GLUT 2 expression showed a steady increase in number and volume fraction from Wk 7 to Wk 65. GLUT 1 was lacking in GSF but occurred in some MCF from Wk 50 onward. The liver type glucose transporter GLUT 2 was decreased in all adenomas and hepatocellular carcinomas (HCC). In three of seven adenomas and 10 of 12 carcinomas, expression of GLUT 1 was increased compared with normal liver parenchyma. In two cases of adenoid HCC, cells of ductular formations coexpressed GLUT 2 and GLUT 1. In contrast, normal bile ducts, bile duct proliferations, and cystic cholangiomas expressed only GLUT 1. Seven of 12 HCC contained many microvessels intensely stained for GLUT 1, a phenomenon never observed in normal liver. Whenever adenoid tumor formations occurred, GLUT 1-positive microvessels were located in the immediate vicinity of these formations. Only in one HCC were such microvessels found in the absence of adenoid formations. Our studies indicate that a reduction of GLUT 2 expression occurs already in early preneoplastic hepatic foci and is maintained throughout hepatocarcinogenesis, including benign and malignant neoplasms. Reexpression of GLUT 1, however, appears in a few MCF and in the majority of adenomas and carcinomas.

Sensitive headspace gas chromatography analysis of free and conjugated 1-methoxy-2-propanol in urine

Glycol ethers still continue to be a workplace hazard due to their important use on an industrial scale. Currently, chronic occupational exposures to low levels of xenobiotics become increasingly relevant. Thus, sensitive analytical methods for detecting biomarkers of exposure are of interest in the field of occupational exposure assessment. 1-Methoxy-2-propanol (1M2P) is one of the dominant glycol ethers and the unmetabolized urinary fraction has been identified to be a good biological indicator of exposure. An existing analytical method including a solid-phase extraction and derivatization before GC/FID analysis is available but presents some disadvantages. We present here an alternative method for the determination of urinary 1M2P based on the headspace gas chromatography technique. We determined the 1M2P values by the direct headspace method for 47 samples that had previously been assayed by the solid-phase extraction and derivatization gas chromatography procedure. An inter-method comparison based on a Bland-Altman analysis showed that both techniques can be used interchangeably. The alternative method showed a tenfold lower limit of detection (0.1 mg/L) as well as good accuracy and precision which were determined by several urinary 1M2P analyses carried out on a series of urine samples obtained from a human volunteer study. The within- and between-run precisions were generally about 10%, which corresponds to the usual injection variability. We observed that the differences between the results obtained with both methods are not clinically relevant in comparison to the current biological exposure index of urinary 1M2P. Accordingly, the headspace gas chromatography technique turned out to be a more sensitive, accurate, and simple method for the determination of urinary 1M2P.[Authors]

In vivo metabolic profiling of glioma-initiating cells using proton magnetic resonance spectroscopy at 14.1 Tesla.

In the last decade, evidence has emerged indicating that the growth of a vast majority of tumors including gliomas is sustained by a subpopulation of cancer cells with stem cell properties called cancer initiating cells. These cells are able to initiate and propagate tumors and constitute only a fraction of all tumor cells. In the present study, we showed that intracerebral injection of cultured glioma-initiating cells into nude mice produced fast growing tumors showing necrosis and gadolinium enhancement in MR images, whereas gliomas produced by injecting freshly purified glioma-initiating cells grew slowly and showed no necrosis and very little gadolinium enhancement. Using proton localized spectroscopy at 14.1 Tesla, decreasing trends of N-acetylaspartate, glutamate and glucose concentrations and an increasing trend of glycine concentration were observed near the injection site after injecting cultured glioma-initiating cells. In contrast to the spectra of tumors grown from fresh cells, those from cultured cells showed intense peaks of lipids, increased absolute concentrations of glycine and choline-containing compounds, and decreased concentrations of glutamine, taurine and total creatine, when compared with a contralateral non-tumor-bearing brain tissue. A decrease in concentrations of N-acetylaspartate and γ-aminobutyrate was found in both tumor phenotypes after solid tumor formation. Further investigation is needed to determine the cause of the dissimilarities between the tumors grown from cultured glioma-initiating cells and those from freshly purified glioma-initiating cells, both derived from human glioblastomas.

HA-1 and the SMCY-derived peptide FIDSYICQV (H-Y) are immunodominant minor histocompatibility antigens after bone marrow transplantation.

BACKGROUND: Allogeneic bone marrow donors can be incompatible at different levels. Even HLA-identical pairs will be still incompatible for numerous minor histocompatibility antigens (mHag). Nevertheless, some incompatibilities are found to be associated with an increased risk of graft-versus-host disease (GVHD), which could be related to the way the immune system recognizes these antigens. METHODS: We determined the specificity of cytotoxic T-cell clones isolated during acute GVHD or during bone marrow graft rejection in patients (n=14) transplanted with marrow from donors who were histoincompatible for different minor and/or major histocompatibility antigens. RESULTS: We found a clear hierarchy among the different types of histoincompatibilities. In three combinations mismatched for a class I allele, all 27 clones isolated during GVHD were specific for the incompatible HLA molecule. In the 11 class I-identical combinations, 14 different mHags were recognized. The mHag HA-1, known to have a significant impact on the development of GVHD, was recognized in the two HA-1-incompatible combinations. In one of these combinations, which was sex mismatched, all 56 clones analyzed were directed against HA-1, demonstrating the dominance of this mHag. In the four HA-1-compatible, sex-mismatched combinations, the anti-H-Y response was directed against one immunodominant epitope rather than against multiple Y-chromosome-encoded epitopes. All male specific cytotoxic T lymphocytes (n=15) recognized the same high-performance liquid chromatography-purified peptide fraction presented by T2 cells. Moreover, all cytotoxic T lymphocytes tested (n=6) were specific for the SMCY-derived peptide FIDSYICQV, originally described as being the H-Y epitope recognized in the context of HLA-A*0201. CONCLUSIONS: Some histocompatibility antigens are recognized in an immunodominant fashion and will therefore be recognized in the majority of mismatched combinations. Only for such antigens, correlations between mismatches and the occurrence of GVHD or graft rejections will be found.

Relations entre la pharmacocinétique de population de l'imatinib et l'alpha-1-glycoproteine acide chez des patients hémato-oncologiques

Introduction: La disposition de l'imatinib (Glivec®) implique des systèmes connus pour de grandes différences inter-individuelles, et l'on peut s'attendre à ce que l'exposition à ce médicament varie largement d'un patient à l'autre. L'alpha-1-glycoprotéine acide (AAG), une protéine circulante liant fortement l'imatinib, représente l'un de ces systèmes. Objectif: Cette étude observationnelle visait à explorer l'influence de l'AAG plasmatique sur la pharmacocinétique de l'imatinib. Méthode: Une analyse de population a été effectuée avec le programme NONMEM sur 278 échantillons plasmatiques issus de 51 patients oncologiques. L'influence des taux d'AAG sur la clairance (CL) et le volume de distribution (Vd) a ainsi été étudiée. Résultats: Un modèle à un compartiment avec absorption de premier ordre a permis de décrire les données. Une relation hyperbolique entre taux d'AAG et CL ou Vd a été observée. Une approche mécanistique a donc été élaborée, postulant que seule la concentration libre subissait une élimination du premier ordre, et intégrant la constante de dissociation comme paramètre du modèle. Cette approche a permis de déterminer une CLlibre moyenne de 1310 l/h et un Vd de 301 l. Par comparaison, la CLtotale déterminée initialement était de 14 l/h. La CLlibre est affectée par le poids corporel et le type de pathologie. Qui plus est, ce modèle a permis d'estimer in vivo la constante d'association entre imatinib et AAG (5.5?106 l/mol), ainsi que la fraction libre moyenne de l'imatinib (1.1%). La variabilité inter-individuelle estimée pour la disposition de l'imatinib (17% sur CLlibre et 66% sur Vd) diminuait globalement de moitié avec le modèle incorporant l'impact de l'AAG. Discussion-conclusion: De tels résultats clarifient l'impact de la liaison protéinique sur le devenir de l'imatinib. Des taux élevés d'AAG ont été présumés représenter un facteur de résistance à l'imatinib. Toutefois, cela est peu probable, notre modèle prédisant que la concentration libre reste inchangée. D'un autre côté, s'il est un jour démontré que l'imatinib requiert un programme de suivi thérapeutique (TDM), la mesure des concentrations libres, ou la correction des concentrations totales en fonction des taux d'AAG, devraient être envisagées pour une interprétation précise des résultats.

Relationship between imatinib population pharmacokinetics and alpha-1-acid glycoprotein

Objectives: Considering the large inter-individual differences in the function of the systems involved in imatinib disposition, exposure to this drug can be expected to vary widely among patients. Among those known systems is alpha-1-acid glycoprotein (AGP), a circulating protein that strongly binds imatinib. This observational study aimed to explore the influence of plasma AGP on imatinib pharmacokinetics. Methods: A population pharmacokinetic analysis was performed using NONMEM based on 278 plasma samples from 51 oncologic patients, for whom both total imatinib and AGP plasma concentrations were measured. The influence of this biological covariate on oral clearance and volume of distribution was examined. Results: A one-compartment model with first-order absorption appropriately described the data. A hyperbolic relationship between plasma AGP levels and oral clearance, as well as volume of distribution was observed. A mechanistic approach was built up, postulating that only the unbound imatinib concentration was able to undergo first-order elimination through an unbound clearance process, and integrating the dissociation constant as a parameter in the model. This approach allowed determining an average (± SEM) free clearance of 1310 (± 172) L/h and a volume of distribution of 301 (± 23) L. By comparison, the total clearance previously determined was 14 (± 1) L/h. Free clearance was affected by body weight and pathology diagnosis. Moreover, this model provided consistent estimates of the association constant between imatinib and AGP (5.5?106 L/mol) and of the average in vivo free fraction of imatinib (1.1%). The variability observed (17% for free clearance and 66% for volume of distribution) was less than the one previously reported without considering AGP impact. AGP explained indeed about one half of the variability observed in total imatinib disposition. Conclusion: Such findings clarify in part the in vivo impact of protein binding on imatinib disposition and might raise again the question whether high levels of AGP could represent a resistance factor to imatinib. This remains however questionable, as it is not expected to affect free drug concentrations. On the other hand, would imatinib be demonstrated as a drug requiring therapeutic drug monitoring, either the measurement of free concentration or the correction of the total concentration by the actual AGP plasma levels should be considered for accurate interpretation of the results.

Renal effects of adenosine A1-receptor blockade with 8-cyclopentyl-1,3-dipropylxanthine in hypoxemic newborn rabbits.

The key role of intrarenal adenosine in mediating the hypoxemic acute renal insufficiency in newborn rabbits has been well demonstrated using the nonspecific adenosine antagonist theophylline. The present study was designed to define the role of adenosine A1 receptors during systemic hypoxemia by using the specific A1-receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX). Renal function parameters were assessed in 31 anesthetized and mechanically ventilated newborn rabbits. In normoxia, DPCPX infusion induced a significant increase in diuresis (+44%) and GFR (+19%), despite a significant decrease in renal blood flow (RBF) (-22%) and an increase in renal vascular resistance (RVR) (+37%). In hypoxemic conditions, diuresis (-19%), GFR (-26%), and RBF (-35%) were decreased, whereas RVR increased (+33%). DPCPX administration hindered the hypoxemia-induced decrease in GFR and diuresis. However, RBF was still significantly decreased (-27%), whereas RVR increased (+22%). In all groups, the filtration fraction increased significantly. The overall results support the hypothesis that, in physiologic conditions, intrarenal adenosine plays a key role in regulating glomerular filtration in the neonatal period through preferential A1-mediated afferent vasoconstriction. During a hypoxemic stress, the A1-specific antagonist DPCPX only partially prevented the hypoxemia-induced changes, as illustrated by the elevated RVR and drop in RBF. These findings imply that the contribution of intrarenal adenosine to the acute adverse effects of hypoxemia might not be solely mediated via the A1 receptor.

A liver protein fraction regulating hormone-dependent in vitro transcription from the vitellogenin genes induces their expression in Xenopus oocytes.

Xenopus laevis oocytes were used to assay for trans-acting factors shown previously to be involved in the liver-specific regulation of the vitellogenin genes in vitro. To this end, crude liver nuclear extracts obtained from adult estrogen-induced Xenopus females were fractionated by heparin-Sepharose chromatography using successive elutions with 0.1, 0.35, 0.6, and 1.0 M KCl. When these four fractions were injected into oocytes, only the 0.6-M KCl protein fraction significantly stimulated mRNA synthesis from the endogenous B class vitellogenin genes. This same fraction induced estrogen-dependent in vitro transcription from the vitellogenin B1 promoter, suggesting that it contains at least a minimal set of basal transcription factors as well as two positive factors essential for vitellogenin in vitro transcription, i.e. the NF-I-like liver factor B and the estrogen receptor (ER). The presence of these two latter factors was determined by footprinting and gel retardation assays, respectively. In contrast, injection of an expression vector carrying the sequence encoding the ER was unable to activate transcription from the oocyte chromosomal vitellogenin genes. This suggests that the ER alone cannot overcome tissue-specific barriers and that one or several additional liver components participate in mediating tissue-specific expression of the vitellogenin genes. In this respect, we present evidence that the oocyte germinal vesicles contain an NF-I-like activity different from that found in hepatocytes of adult frogs. This observation might explain the lack of vitellogenin gene activation in oocytes injected with the ER cDNA only.

Upregulation of Tim-3 and PD-1 expression is associated with tumor antigen-specific CD8+ T cell dysfunction in melanoma patients.

The paradoxical coexistence of spontaneous tumor antigen-specific immune responses with progressive disease in cancer patients furthers the need to dissect the molecular pathways involved in tumor-induced T cell dysfunction. In patients with advanced melanoma, we have previously shown that the cancer-germline antigen NY-ESO-1 stimulates spontaneous NY-ESO-1-specific CD8(+) T cells that up-regulate PD-1 expression. We also observed that PD-1 regulates NY-ESO-1-specific CD8(+) T cell expansion upon chronic antigen stimulation. In the present study, we show that a fraction of PD-1(+) NY-ESO-1-specific CD8(+) T cells in patients with advanced melanoma up-regulates Tim-3 expression and that Tim-3(+)PD-1(+) NY-ESO-1-specific CD8(+) T cells are more dysfunctional than Tim-3(-)PD-1(+) and Tim-3(-)PD-1(-) NY-ESO-1-specific CD8(+) T cells, producing less IFN-γ, TNF, and IL-2. Tim-3-Tim-3L blockade enhanced cytokine production by NY-ESO-1-specific CD8(+) T cells upon short ex vivo stimulation with cognate peptide, thus enhancing their functional capacity. In addition, Tim-3-Tim-3L blockade enhanced cytokine production and proliferation of NY-ESO-1-specific CD8(+) T cells upon prolonged antigen stimulation and acted in synergy with PD-1-PD-L1 blockade. Collectively, our findings support the use of Tim-3-Tim-3L blockade together with PD-1-PD-L1 blockade to reverse tumor-induced T cell exhaustion/dysfunction in patients with advanced melanoma.

Human Prominin-1 (CD133) Is Detected in Both Neoplastic and Non-Neoplastic Salivary Gland Diseases and Released into Saliva in a Ubiquitinated Form.

Prominin-1 (CD133) is physiologically expressed at the apical membranes of secretory (serous and mucous) and duct cells of major salivary glands. We investigated its expression in various human salivary gland lesions using two distinct anti-prominin-1 monoclonal antibodies (80B258 and AC133) applied on paraffin-embedded sections and characterized its occurrence in saliva. The 80B258 epitope was extensively expressed in adenoid cystic carcinoma, in lesser extent in acinic cell carcinoma and pleomorphic adenoma, and rarely in mucoepidermoid carcinoma. The 80B258 immunoreactivity was predominately detected at the apical membrane of tumor cells showing acinar or intercalated duct cell differentiation, which lined duct- or cyst-like structures, and in luminal secretions. It was observed on the whole cell membrane in non-luminal structures present in the vicinity of thin-walled blood vessels and hemorrhagic areas in adenoid cystic carcinoma. Of note, AC133 labeled only a subset of 80B258-positive structures. In peritumoral salivary gland tissues as well as in obstructive sialadenitis, an up-regulation of prominin-1 (both 80B258 and AC133 immunoreactivities) was observed in intercalated duct cells. In most tissues, prominin-1 was partially co-expressed with two cancer markers: carcinoembryonic antigen (CEA) and mucin-1 (MUC1). Differential centrifugation of saliva followed by immunoblotting indicated that all three markers were released in association with small membrane vesicles. Immuno-isolated prominin-1-positive vesicles contained CEA and MUC1, but also exosome-related proteins CD63, flotillin-1, flotillin-2 and the adaptor protein syntenin-1. The latter protein was shown to interact with prominin-1 as demonstrated by its co-immunoisolation. A fraction of saliva-associated prominin-1 appeared to be ubiquitinated. Collectively, our findings bring new insights into the biochemistry and trafficking of prominin-1 as well as its immunohistochemical profile in certain types of salivary gland tumors and inflammatory diseases.