Reactivity spectrum of 30 monoclonal antimelanoma antibodies to a panel of 28 melanoma and control cell lines.

Thirty monoclonal antibodies from eight laboratories exchanged after the First Workshop on Monoclonal Antibodies to Human Melanoma held in March 1981 at NIH were tested in an antibody-binding radioimmunoassay using a panel of 28 different cell lines. This panel included 12 melanomas, three neuroblastomas, four gliomas, one retinoblastoma, four colon carcinomas, one lung carcinoma, one cervical carcinoma, one endometrial carcinoma, and one breast carcinoma. The reactivity pattern of the 30 monoclonal antibodies tested showed that none of them were directed against antigens strictly restricted to melanoma, but that several of them recognize antigenic structures preferentially expressed on melanoma cells. A large number of antibodies were found to crossreact with gliomas and neuroblastomas. Thus, they seem to recognize neuroectoderm associated differentiation antigens. Four monoclonal antibodies produced in our laboratory were further studied for the immunohistological localization of melanoma associated antigens on fresh tumor material. In a three-layer biotin-avidin-peroxidase system each antibody showed a different staining pattern with the tumor cells, suggesting that they were directed against different antigens.

Hydrogen isotope fractionations between amphiboles, micas, and fluids in alkaline igneous intrusions

RÉSUMÉ DE LA THÈSE Les teneurs des amphiboles en éléments majeurs et en isotopes stables ont été analysées dans plusieurs complexes ignés alcalins et hyperalcalins, dans le but de déterminer l'importance des variations de composition des minéraux pour le fractionnement isotopique de l'hydrogène dans un système naturel minéral-magma-fluide. Cette étude se concentre principalement sur les syénites néphéliniques de complexes intrusifs alcalins bien connus mais à chimie variable, dont les amphiboles, ainsi que d'autres silicates hydratés tels que micas et eudialytes, lorsque cela était possible, ont été séparés. L'intérêt principal s'est porté sur le complexe alcalin d'Ilímaussaq de la Province du Gardar, au Sud du Groenland. Dans une optique de comparaison, nous avons collecté et analysé d'autres échantillons provenant du complexe de Tugtutôq (Sud Groenland), des complexes de Khibina et Lovozero (Péninsule de Kola, Russie), du Mont St-Hilaire et du Mont Royal (Canada) et de 6 autres du nord-ouest de la Namibie (Cape Cross, Okenyenya, Messum, Etaneno, Kalkfeld,et Okorusu). Les compositions isotopiques de l'hydrogène des amphiboles des ces différentes zones présentent de grandes variations (-227 à -700/00), ce qui est atypique pour des magmas d'origine mantellique. Les valeurs comprises entre -80 et -400/00 indiquent une provenance du manteau. Ces larges variations de compositions ainsi que l'extrême appauvrissement en isotope lourd de l'hydrogène (D), en comparaison avec d'autres roches ignées, semblent être propres.aux roches alcalines et hyperalcalines de ce type, ce qui indiquerait un processus commun. Les différents complexes alcalins choisis présentent un large intervalle de composition chimique des amphiboles. La caractérisation des amphiboles par microscopie électronique et par spectroscopie Mössbauer contribuent à observer le contrôle du Fe sur le fractionnement des isotopes de l'hydrogène. En effet, cela a mis en évidence un contrôle du Fe sur le fractionnement et même, dans le cas du complexe hyperalcalin d'Ilímaussaq, une relation entre le rapport Fei3+/FeT et les variations du rapport D/H. Les complexes étudiés diffèrent de par leur index agpaïtique (Na+K/Al) et également de par leur contenu en fer. Les plus hautes valeurs en Fe (27-35 wt%) et en éléments alcalins dans les amphiboles, ainsi que les teneurs de D/H les plus basses et leur grande variation, sont celles du complexe d'Ilímaussaq. Les amphiboles de la Péninsule de Kola et du Canada sont similaires, mais toutefois moins appauvries en D. En ce qui concerne les amphiboles des complexes du NO de la Namibie, elles présentent des compositions isotopiques de l'hydrogène magmatiques normales (-73 à -100 0/00), contiennent moins de Fe (15-17 wt%) et sont fortement enrichies en Ca et moins en Na. Dans ce cas, l'alcalinité est moins importante en comparaison des autres complexes étudiés. En dehors des teneurs en éléments alcalins des amphiboles, l'alcalinité des fluides s'avère également un facteur important, ce qui est cohérent avec certaines suggestions à partir de systèmes expérimentaux. Afin de mieux contraindre ce facteur, des expériences d'échanges hydrothermaux entre les amphiboles et les fluides de salinité différente ont été effectuées en simulant des conditions naturelles. L'approximation d'amphiboles naturelles de complexes ignés alcalins, couplée aux expériences d'échange, aide à préciser les facteurs contrôlant le fractionnement des isotopes de l'hydrogène dans les roches alcalines. Les valeurs extrêmement basses de 3D des amphiboles de ces complexes alcalins peuvent être dues à une combinaison de différents facteurs, telles qu'une haute alcalinité, une haute teneur en Fe et une faible profondeur d'intrusion. Les grandes variations ainsi que les faibles valeurs de SD des amphiboles étudiées peuvent résulter d'un processus magmatique interne et il est peu probable que de l'eau météorique soit impliquée et/ou que le dégazage magmatique ait joué un rôle. THESIS ABSTRACT Major element and stable isotope compositions of amphiboles were analyzed from a number of alkaline and peralkaline igneous complexes in order to determine the importance of compositional variations in minerals to hydrogen isotope fractionations in natural mineral-melt-fluid systems. The thesis mainly focuses on nepheline syenites of well-studied, but chemically variable alkaline intrusive rocks, from which amphiboles and, if possible, other hydrous silicates such as micas and eudialytes were separated. The system of primary interest was the alkaline Ilímaussaq Complex of the Gardar Province of South Greenland. For the purpose of comparison additional samples were collected and examined from the Tugtutôq Complex (South Greenland), the Khibina and Lovozero Complexes (Kola Peninsular, Russia), Mount St-Hilaire and Mount Royal (Canada) and six further complexes from NW Namibia (Cape Cross, Okenyenya, Messum, Etaneno, Kalkfeld, and Okorusu). The hydrogen isotope compositions of amphiboles from the localities studied differ greatly, which is atypical for amphiboles from mantle, range between - 227 and - 700/00 (latter compatible with a simple mantle origin). As this wide range in compositions and the extreme depletion in the heavy hydrogen isotope (D) content relative to other igneous rocks appear to be unique to alkaline to peralkaline rocks of this type, a common process is indicated. The different alkaline complexes chosen cover a wide range of amphibole chemical compositions. Detailed chemical characterization of amphiboles by electron microprobe and Mössbauer spectroscopy analyses helped to constrain the control of Fe on the H-isotope fractionations. Complete characterization of the chemical compositions of the amphiboles support Fe-control on fractionations and at least for the peralkaline Ilímaussaq complex a relationship between Fe3+/FeT ratios and variations in D/H. The studied complexes differ in their agpaitic index (Na+K/Al) and also in their Fe-content. The most iron (27-35 wt. %) and alkaline element rich amphiboles, with the lowermost D/H ratio, as well with very wide range, are the ones from Ilímaussaq complex. Similar, but less D depleted amphiboles are from the Kola Peninsula and the Canadian localities. The complexes described from NW Namibia have amphiboles with normal magmatic hydrogen isotope composition (-730/00 to -1000/00), and have less Fe-content (15-17 wt. %), and are more Ca-and less Na-rich. In this case alkalinity is not that important in comparison to the other studied complexes. Beside the alkaline element contents in the amphiboles, the alkalinity of the fluids has been found to be an important factor, in conjunction with earlier suggestions from experimental systems. To further constrain this factor, hydrothermal exchange experiments between amphiboles and fluids of different salinity simulating natural conditions were performed. The approach of examining natural amphiboles from alkaline igneous complexes in parallel to performing exchange experiments - helped to further constrain the factors controlling the H-isotope fractionations in alkaline rocks. The observed changes between the hydrogen and oxygen isotope compositions of amphiboles and fluids before and after the experiments suggest that another phase was produced during the experiments, which influenced the final hydrogen isotope composition of the system. This presumably hydrous phase has also influenced the Fe3 +/Fe2+ ratio of the amphiboles, which became more oxidized. The extremely low SD values of amphiboles in these alkaline complexes may be due to a combination of different factors such as high alkalinity, high Fe-content, and shallow intrusion depths. This wide range and the low SD values of the amphiboles studied might be a result of internal, magmatic processes and it is unlikely that meteoric water was involved and/or magmatic degassing played an important role. RÉSUMÉ DE LA THÈSE (pour le grand public) Fractionnement isotopique de l'hydrogène entre amphiboles, micas et fluides dans des intrusions alcalines Zsófia Wáczek Directeur de thèse, Prof. Torsten W. Vennemann Institut de Minéralogie et Géochimie, Université de Lausanne Les roches alcalines et celles qui leurs sont associées sont des sources importantes de nombreux minéraux et minerais, tels l'apatite, le niobium, le diamant et autres pierres précieuses. Cette étude se concentre sur des complexes alcalins localisés dans le sud du Groenland, au Canada, dans la péninsule de Kola en Russie et au nord-ouest de la Namibie. Ces complexes sont composés de roches ayant cristallisé à partir de magmas et de fluides très enrichis en alcalins. Cet enrichissement permet la précipitation de minéraux inhabituels riches en potassium et/ou sodium, telles les amphiboles sodiques, également enrichies en fer. Les amphiboles étudiées ont des compositions calciques, sodi-calciques et sodiques, qui reflètent leurs différents environnements de formation. Des études précédentes ont révélé une large gamme de rapports isotopiques de l'hydrogène dans les amphiboles de roches hyperalcalines, dont certains extrêmement bas. Cette variation importante est très intrigante, sachant que des valeurs entre -40 et -800/00 correspondent à des silicates ignés hydratés et non altérés, alors que des valeurs descendant jusqu'a -1500/00 nécessiteraient une altération par de l'eau météorique et/ou une contamination par les roches environnantes ou des sédiments riches en matière organique. Dans lé cas précis du complexe d'Ilímaussaq (sud du Groenland), aucune de ces explications n'a pu être démontrée et des valeurs encore plus faibles ont été trouvées. Le complexe d'Ilímaussaq présente des valeurs de rapport isotopique de l'hydrogène entre -227 et -500/00 dans les amphiboles. Une origine mantellique permet d'expliquer les valeurs élevées, mais d'autres processus doivent entrer en jeu pour engendrer les valeurs les plus négatives. C'est à l'identification de ces processus que nous nous sommes attachés dans ce travail. Les grandes variations observées dans les teneurs en fer et dans le rapport Fe3+/FeT des roches et des minéraux de ces complexes sont corrélées avec d'autres paramètres chimiques, tels que la composition isotopique de l'hydrogène dans les amphiboles. Nous avons dès lors abordé les questions suivantes: quelle est la relation entre la teneur en fer des amphiboles et leur composition isotopique? Que nous apprennent les changements de la teneur en fer et les changements dans le rapport Fe3+/FeT sur les processus pétrologiques dans ces roches? Pour répondre à ces questions, nous avons analysé les compositions isotopiques de l'oxygène et de l'hydrogène dans les amphiboles et d'autres silicates hydratés. La composition chimique et le rapport Fe3+/FeT des amphiboles ont également été déterminés. Des expériences hydrothermales simulant des conditions naturelles ont été entreprises afin de mieux comprendre les processus de fractionnement isotopiques dans ces systèmes très alcalins. Nos conclusions sont les suivantes: (1) Les valeurs extrêmement faibles ainsi que les larges variations des rapports isotopiques de l'hydrogène des amphiboles de ces complexes alcalins sont dues à une combinaison de facteurs tels que la forte alcalinité, la haute teneur en fer et la profondeur très faible de l'intrusion. (2) Ces valeurs sont probablement le résultat de processus magmatiques internes. (3) Il est peu probable que les eaux météoriques et/ou le dégazage magmatique aient joué un rôle lors de la formation de ces amphiboles. (4) Certaines corrélations, en accord avec les études précédentes, ont pu être trouvées au niveau des concentrations en fer. (5) Dans le cas du complexe d'Ilímaussaq exclusivement, une relation a été trouvée entre le rapport Fe3+/FeT et la composition isotopique de l'hydrogène des amphiboles.

The roles of flux- and decompression melting and their respective fractionation lines for continental crust formation: Evidence from the Kohistan arc

Delamination and foundering of the lower continental crust (LCC) into the mantle is part of the crust-forming mechanism. However, knowledge of the composition and mineralogy of the preserved or delaminated LCC over geological timescales remains scarce. We provide a synopsis of recent research within the Kohistan arc (Pakistan) and demonstrate that hydrous and less hydrous liquid lines of descent related to flux assisted and decompression mantle melting, respectively, produce compositionally different lower crustal rocks. The argument refers to two lower crustal sections exposed in Kohistan, the older Southern Plutonic Complex (SPC) and the younger Chilas Complex. The SPC typifies a hydrous, high-pressure fractionation sequence of olivine-pyroxenes-garnet-Fe/Ti-oxide-amphibole-plagioclase. The Chilas Complex illustrates a less hydrous fractionation sequence of olivine-clinopyroxene-orthopyroxene-plagioclase-amphibole. Despite the similarity of the Chilas Complex rocks to proposed lower crust compositions, the less hydrous fractionation results in unrealistically small volumes of silica-rich rocks, precluding the Chilas Complex gabbros to represent the magmatic complement to the upper crust. The composition of the SPC lower crust differs markedly from bulk lower crust estimates, but is complementary to silica-rich rocks exposed along this section and in the Kohistan batholith. These observations inspire a composite model for the formation of continental crust (CC) where the negatively buoyant delaminated and the buoyant preserved lower continental crusts (LCC) differ in genesis, mineralogy, and composition. We propose that the upper, non-sedimentary subsequent removal of the complementary, negatively buoyant garnet-pyroxene-amphibole-plagioclase-rich cumulates. In contrast, the LCC, which is buoyant and preserved over geological timescales, is formed by less hydrous parental mantle melts. We suggest that the bulk continental crust composition is related to mixing of these petrologically not directly related end members. Published by Elsevier B.V.

Engineering tolerance into transplanted beta cell lines.

In this paper we explore the possibility of improving, by genetic engineering, the resistance of insulin-secreting cells to the metabolic and inflammatory stresses that are anticipated to limit their function and survival when encapsulated and transplanted in a type 1 diabetic environment. We show that transfer of the Bcl-2 antiapoptotic gene, and of genes specifically interfering with cytokine intracellular signaling pathways, greatly improves resistance of the cells to metabolic limitations and inflammatory stresses.

Combination of carbon isotope ratio with hydrogen isotope ratio determinations in sports drug testing.

Carbon isotope ratio (CIR) analysis has been routinely and successfully applied to doping control analysis for many years to uncover the misuse of endogenous steroids such as testosterone. Over the years, several challenges and limitations of this approach became apparent, e.g., the influence of inadequate chromatographic separation on CIR values or the emergence of steroid preparations comprising identical CIRs as endogenous steroids. While the latter has been addressed recently by the implementation of hydrogen isotope ratios (HIR), an improved sample preparation for CIR avoiding co-eluting compounds is presented herein together with newly established reference values of those endogenous steroids being relevant for doping controls. From the fraction of glucuronidated steroids 5β-pregnane-3α,20α-diol, 5α-androst-16-en-3α-ol, 3α-Hydroxy-5β-androstane-11,17-dione, 3α-hydroxy-5α-androstan-17-one (ANDRO), 3α-hydroxy-5β-androstan-17-one (ETIO), 3β-hydroxy-androst-5-en-17-one (DHEA), 5α- and 5β-androstane-3α,17β-diol (5aDIOL and 5bDIOL), 17β-hydroxy-androst-4-en-3-one and 17α-hydroxy-androst-4-en-3-one were included. In addition, sulfate conjugates of ANDRO, ETIO, DHEA, 3β-hydroxy-5α-androstan-17-one plus 17α- and androst-5-ene-3β,17β-diol were considered and analyzed after acidic solvolysis. The results obtained for the reference population encompassing n = 67 males and females confirmed earlier findings regarding factors influencing endogenous CIR. Variations in sample preparation influenced CIR measurements especially for 5aDIOL and 5bDIOL, the most valuable steroidal analytes for the detection of testosterone misuse. Earlier investigations on the HIR of the same reference population enabled the evaluation of combined measurements of CIR and HIR and its usefulness regarding both steroid metabolism studies and doping control analysis. The combination of both stable isotopes would allow for lower reference limits providing the same statistical power and certainty to distinguish between the endo- or exogenous origin of a urinary steroid.

Calcium phosphate transfection generates mammalian recombinant cell lines with higher specific productivity than polyfection.

Transfection with polyethylenimine (PEI) was evaluated as a method for the generation of recombinant Chinese hamster ovary (CHO DG44) cell lines by direct comparison with calcium phosphate-DNA coprecipitation (CaPO4) using both green fluorescent protein (GFP) and a monoclonal antibody as reporter proteins. Following transfection with a GFP expression vector, the proportion of GFP-positive cells as determined by flow cytometry was fourfold higher for the PEI transfection as compared to the CaPO4 transfection. However, the mean level of transient GFP expression for the cells with the highest level of fluorescence was twofold greater for the CaPO4 transfection. Fluorescence in situ hybridization on metaphase chromosomes from pools of cells grown under selective pressure demonstrated that plasmid integration always occurred at a single site regardless of the transfection method. Importantly, the copy number of integrated plasmids was measurably higher in cells transfected with CaPO4. The efficiency of recombinant cell line recovery under selective pressure was fivefold higher following PEI transfection, but the average specific productivity of a recombinant antibody was about twofold higher for the CaPO4-derived cell lines. Nevertheless, no difference between the two transfection methods was observed in terms of the stability of protein production. These results demonstrated the feasibility of generating recombinant CHO-derived cell lines by PEI transfection. However, this method appeared inferior to CaPO4 transfection with regard to the specific productivity of the recovered cell lines.

Two Cases of Interferon-Alpha-Induced Sarcoidosis Koebnerized along Venous Drainage Lines: New Pathogenic Insights and Review of the Literature of Interferon-Induced Sarcoidosis.

Sarcoidosis is a systemic granulomatous disorder of unknown origin commonly affecting the lung, the lymphoid system and the skin. We report here two cases of cutaneous sarcoidosis in two former intravenous drug users following interferon (IFN)-α and ribavirin therapy for chronic hepatitis C. Both patients developed skin sarcoidosis along venous drainage lines of both forearms, coinciding with the areas of prior drug injections. The unique distribution of the skin lesions suggests that tissue damage induced by repeated percutaneous drug injections represents a trigger for the local skin manifestation of sarcoidosis. Interestingly, skin damage was recently found to induce the local expression IFN-α, a well-known trigger of sarcoidosis in predisposed individuals. Here we review the literature on sarcoidosis elicited in the context of IFN-α therapy and propose a new link between the endogenous expression of IFN-α and the induction of disease manifestations in injured skin. © 2013 S. Karger AG, Basel.

Internal arsenite bioassay calibration using multiple reporter cell lines

Bioassays with bioreporter bacteria are usually calibrated with analyte solutions of known concentrations that are analysed along with the samples of interest. This is done as bioreporter output (the intensity of light, fluorescence or colour) does not only depend on the target concentration, but also on the incubation time and physiological activity of the cells in the assay. Comparing the bioreporter output with standardized colour tables in the field seems rather difficult and error-prone. A new approach to control assay variations and improve application ease could be an internal calibration based on the use of multiple bioreporter cell lines with drastically different reporter protein outputs at a given analyte concentration. To test this concept, different Escherichia coli-based bioreporter strains expressing either cytochrome c peroxidase (CCP, or CCP mutants) or β-galactosidase upon induction with arsenite were constructed. The reporter strains differed either in the catalytic activity of the reporter protein (for CCP) or in the rates of reporter protein synthesis (for β-galactosidase), which, indeed, resulted in output signals with different intensities at the same arsenite concentration. Hence, it was possible to use combinations of these cell lines to define arsenite concentration ranges at which none, one or more cell lines gave qualitative (yes/no) visible signals that were relatively independent of incubation time or bioreporter activity. The discriminated concentration ranges would fit very well with the current permissive (e.g. World Health Organization) levels of arsenite in drinking water (10 µg l−1).

Mixing of Rhône River water in Lake Geneva (Switzerland-France) inferred from stable hydrogen and oxygen isotope profiles

Depth profiles were sampled at different locations throughout Lake Geneva on a monthly and seasonal basis over the course of 2 years and analysed for their stable hydrogen and oxygen isotope compositions. The isotopic compositions indicate an isotopic stratification in the metalimnion during summer and fall. This is related to mixing of Rhône River water, which in summer is dominated by snow and glacier melt waters, and lake water, with the latter having a homogenous isotopic composition. The observed interflow layer is 7-15 m thick and can be traced by the distinct stable isotope composition of the water for about 55 km throughout the lake as well as into shallow bay regions. Depth of the interflow layer close to the Rhône River mouth is similar to those previously described based on echo-soundings and turbidity profiles of sediment dispersion. In contrast to previous descriptions of the interflow within Lake Geneva, the stable isotope compositions allow for direct, natural tracing of the Rhône River water even in cases where the turbidity and conductivity measurements do not indicate such an interflow. In addition, the method allows for a quantification of the Rhône River and lake water in the interflow with the fraction of Rhône River water within the interflow estimated to be up to 37% in summer. The isotopic composition further indicates different vertical mixing processes within the two lake basins of Lake Geneva, related to the density gradients and local stability within the water column. The method may be applicable to other lakes in catchments with large differences in the topography as water that originates from high altitudes or glaciers has a distinct oxygen and hydrogen isotope composition compared to other sources of water originating at lower altitudes and/or from direct precipitation over the lake. Stable isotope measurements thus improve the understanding of the circulation of water within the lake, which is fundamental for an evaluation of the water residence times, dissolved pollutant and nutrient transport as well as oxygenation.

Development of stable cell lines for production or regulated expression using matrix attachment regions.

One of the major hurdles of isolating stable, inducible or constitutive high-level producer cell lines is the time-consuming selection procedure. Given the variation in the expression levels of the same construct in individual clones, hundreds of clones must be isolated and tested to identify one or more with the desired characteristics. Various boundary elements (BEs), matrix attachment regions, and locus control regions (LCRs) were screened for their ability to augment the expression of heterologous genes in Chinese hamster ovary (CHO) cells. Of the chromatin elements assayed, the chicken lysozyme matrix-attachment region (MAR) was the only element to significantly increase stable reporter expression. We found that the use of the MAR increases the proportion of high-producing clones, thus reducing the number of clones that need to be screened. These benefits are observed both for constructs with MARs flanking the transgene expression cassette, as well as when constructs are co-transfected with the MAR on a separate plasmid. Moreover, the MAR was co-transfected with a multicomponent regulatable beta-galactosidase expression system in C2C12 cells and several clones exhibiting regulated expression were identified. Hence, MARs are useful in the development of stable cell lines for production or regulated expression.

Signal transduction by the cloned glucagon-like peptide-1 receptor: comparison with signaling by the endogenous receptors of beta cell lines.

Glucagon-like peptide-1 (GLP-1) is a gastrointestinal hormone that potentiates glucose-induced insulin secretion by pancreatic beta cells. The mechanisms of interaction between GLP-1 and glucose signaling pathways are not well understood. Here we studied the coupling of the cloned GLP-1 receptor, expressed in fibroblasts or in COS cells, to intracellular second messengers and compared this signaling with that of the endogenous receptor expressed in insulinoma cell lines. Binding of GLP-1 to the cloned receptor stimulated formation of cAMP with the same dose dependence and similar kinetics, compared with the endogenous receptor of insulinoma cells. Compared with forskolin-induced cAMP accumulation, that induced by GLP-1 proceeded with the same initial kinetics but rapidly reached a plateau, suggesting fast desensitization of the receptor. Coupling to the phospholipase C pathway was assessed by measuring inositol phosphate production and variations in the intracellular calcium concentration. No GLP-1-induced production of inositol phosphates could be measured in the different cell types studied. A rise in the intracellular calcium concentration was nevertheless observed in transfected COS cells but was much smaller than that observed in response to norepinephrine in cells also expressing the alpha 1B-adrenergic receptor. Importantly, no such increase in the intracellular calcium concentration could be observed in transfected fibroblasts or insulinoma cells, which, however, responded well to thrombin or carbachol, respectively. Together, our data show that interaction between GLP-1 and glucose signaling pathways in beta cells may be mediated uniquely by an increase in the intracellular cAMP concentration, with the consequent activation of protein kinase A and phosphorylation of elements of the glucose-sensing apparatus or of the insulin granule exocytic machinery.

Two cases of interferon-alpha-induced sarcoidosis koebnerized along venous drainage lines : new pathogenic insights and review of the literature of interferon-induced sarcoidosis

La sarcoïdose est une affection inflammatoire granuiomateuse systémique d'origine inconnue touchant le plus fréquemment les poumons, le système lymphoïde, le foie, les yeux et la peau. Dans cet article, nous rapportons deux cas de sarcoïdose cutanée touchant les avant-bras de deux patients anciens toxicomanes traités par interféron-a et ribavirine pour une hépatite C chronique. Nous procédons à une revue de la littérature de la sarcoïdose induite par l'interféron et élaborons une nouvelle hypothèse pathogénique de l'effet Koebner dans la sarcoïdose cutanée. Dans le cas des deux patients que nous décrivons, la distribution des lésions cutanées coïncide avec les anciens sites d'injection d'héroïne le long des trajets veineux des deux avant- bras. Cette distribution unique de l'atteinte cutanée suggère que les dommages tissulaires induits par la répétition d'injections percutanées puissent représenter un terrain favorisant au développement local d'une sarcoïdose cutanée. Fait intéressant, il a été récemment démontré que les cellules dendritiques plasmacytoïdes - sous-type de cellules dendritiques généralement absent de la peau - infiltrent rapidement les sites de peau lésée. Ces cellules sont la source d'une production endogène d'interféron-a, cytokine connue pour promouvoir le processus de cicatrisation, mais également pour favoriser le développement de sarcoïdose chez des individus prédisposés. Ainsi, nous postulons que les lésions de sarcoïdose cutanée limitées le long des trajets veineux - sites préalables d'injection percutanée de drogues - peuvent résulter d'une expression locale supplémentaire d'interféron-a. Celle-ci serait en outre favorisée par le traitement de ribavirine dans le cadre de l'hépatite C, connu pour renforcer la production endogène d'interféron-a. L'identification de nombreuses cellules dendritiques plasmacytoïdes circonscrivant l'inflammation granuiomateuse sur la biopsie cutanée de l'un de nos patients semble être un argument dans ce sens, conforté par l'absence de corps étranger détecté en microscopie par lumière polarisée. Cette observation semble pouvoir représenter un point crucial dans la compréhension des mécanismes physiopathologiques à la base de l'infiltration des cicatrices cutanées par la sarcoïdose. Des investigations supplémentaires doivent encore être effectuées afin de confirmer cette hypothèse.

Phorbol 12-myristate 13-acetate induces surface expression of T3 on human immature T cell lines with and without concomitant expression of the T cell antigen receptor complex.

The T3 complex is known to be expressed on the cell surface of mature T cells together with either the alpha-beta heterodimeric T cell receptor (TCR) or the TCR gamma protein. In a number of immature T cell malignancies, however, T3 has been described exclusively in the cytoplasm. We have investigated five such T cell lines with cytoplasmic T3 and could demonstrate by biosynthetic labeling the presence of the alpha and beta chains of the TCR in the cytoplasm of two of them, CEM and Ichikawa. No surface TCR alpha-beta protein could be detected by staining with the WT31 antibody. These observations, therefore, argue against the concept that expression of the TCR alpha chain controls the surface expression of the T3/TCR complex. Interestingly, phorbol 12-myristate 13-acetate (PMA) induced cell surface expression of T3 protein in these two cell lines only. Moreover, on surface-iodinated CEM cells no association of T3 and TCR molecules could be demonstrated after treatment with PMA, and expression of TCR alpha and beta chains was limited to the cytoplasm. In Ichikawa cells, however, PMA induced surface expression of a mature T3/TCR complex. Our findings indicate that separate regulatory mechanisms may exist for the surface expression of the T3 proteins and for the assembly of the T3/TCR complex.

Gene expression profiling reveals consistent differences between clinical samples of human leukaemias and their model cell lines.

Microarray gene expression profiles of fresh clinical samples of chronic myeloid leukaemia in chronic phase, acute promyelocytic leukaemia and acute monocytic leukaemia were compared with profiles from cell lines representing the corresponding types of leukaemia (K562, NB4, HL60). In a hierarchical clustering analysis, all clinical samples clustered separately from the cell lines, regardless of leukaemic subtype. Gene ontology analysis showed that cell lines chiefly overexpressed genes related to macromolecular metabolism, whereas in clinical samples genes related to the immune response were abundantly expressed. These findings must be taken into consideration when conclusions from cell line-based studies are extrapolated to patients.