Leucocyte | EPFL Graph Search

Les leucocytes (du grec leukos : blanc et kutos : cellule) ou globules blancs sont des cellules produites dans la moelle osseuse et présentes dans le sang, la lymphe, les organes lymphoïdes (ganglions, rate, amygdale et végétations adénoïdes et plaques de Peyer) et de nombreux tissus conjonctifs de l'organisme. Il en existe trois types principaux : les polynucléaires (ou granulocytes), les lymphocytes et les monocytes. Chaque type joue un rôle important au sein du système immunitaire en participant à la protection contre les agressions d'organismes extérieurs de manière coordonnée. De nombreuses pathologies peuvent atteindre ces cellules, par anomalie de production ou de fonctionnement. Description Les leucocytes constituent les éléments cellulaires sanguins les moins nombreux, après les érythrocytes (globules rouges) et les plaquettes. Ils sont caractérisés par une taille en général plus grande, et par la présence d'un noyau. Leur durée de vie dans le sang est de quelque

Statistical Analysis of Chao’s Immune System Simulation

Eric Winnington

Modeling the immune system (IS) means putting together a set of assumptions about its components (cells and organs) and their interactions. Simulations of a model show joint behavior of the components, which for complex realistic models is often impossible to find analytically. Simulations allow us to experiment on how initial concentrations and properties of the immune cells and viruses impact the IS behavior, and gain better quantitative and qualitative insight into how the IS works and why different behavior patterns occur. A simulation, once it has been created, must be reviewed both statistically and analytically as well as validated from the biological point of view. We analyzed Chao’s immune system simulation [1][2] from a statistical and analytical point. We explicited both the Markov chain which was simulated and the underlying process on which Chao’s stage-structured approach was built. Furthermore, we established a test protocol for timestep validation which Chao’s simulator passed. We evaluated Chao’s simulator’s dependence on the random number generator, which was shown to be negligible. Finally, we evaluated the simulator output and our major result is the discovery of a secondary response to a primary infection, an occurrence is not shown in Chao’s dissertation. A tertiary response to the infection is never possible due to the size of the secondary response caused by memory cells.

2005

Microdevice-integrated immunoassays for Point-of-Care Therapeutic Drug Monitoring

Elena-Diana Bojescu

A significant number of drugs exhibit narrow therapeutic windows and high inter-individual pharmacokinetic variability. In such cases, Therapeutic Drug Monitoring (TDM) is compulsory in order to optimize the efficacy of the drug while avoiding adverse effects. Concentration measurements required for dose-adjustments are however complex and are therefore only performed at specialized facilities. The development of a device for accurate whole-blood quantification of critical drugs at the Point-of-Care (POC) would enable fast time-to-result and provide a more convenient solution to patients. This thesis aimed at the design of sample-to-result devices comprising microstructures that allowed for the quantification of small molecules in blood. The designs were based on the development and use of miniaturized fluorescence polarization immunoassays (FPIA). The main feature offered by the FP assay format was the ability to perform homogeneous measurements with no separation or washing steps required. An important result of this thesis is the demonstration that the concentration of small drugs can be quantified in whole blood within paper-like membranes using Fluorescence Polarization Immunoassay (FPIA). Different types of paper-like materials such as glass microfibers, cellulose and filter paper were screened for artefacts such as scattering or autofluorescence. Accurate determination of the fluorescence polarization of red-emitting fluorophores at sub-nanomolar concentrations was found possible within glass fiber membranes. This enabled the development of a competitive immunoassay for the quantification of the antibiotic tobramycin using only 1 ïL of plasma in glass fiber micro-chambers. Furthermore, the same membrane was used for transversal separation of blood cells followed by accurate FPIA read-out at the bottom part of the micro-chamber. Within the therapeutic window, coefficients of variation were around 20% and recoveries between 80-105%, demonstrating the ability to run quantitatively both clinical chemistry and sample preparation by incorporating FPIA in glass fiber membranes. Another important step towards a POC device was the design of a compact, bench-top FP-based analyzer. In this case, glass capillaries were used as detection chambers as they cause little light scattering and for reasons of convenience. Furthermore, the new optical system was employed for tobramycin quantification previously spiked in plasma samples showing good analytical performance in terms of coefficients of variation and recoveries within the therapeutic range of the drug. A more challenging class of drugs are the immunosuppressants, administered in cases of organ transplantation. Here, several fluorescent derivatives of tacrolimus at different wavelengths were synthesized. Their affinity for various biorecognition molecules were tested allowing the choice of a ligand-receptor pair for the development of a FPIA for tacrolimus quantification in buffer. Next, attempts were undertaken to adapt the immunoassay for analysis in whole blood samples. Considerable challenges due to the complexity of the matrix were revealed and initiated efforts to improve the whole blood preparation techniques with the aim of quantifying tacrolimus within its therapeutic range. With the aim of paving the way towards personalized therapies, this thesis makes the realisation of a POC for TDM a realistic goal.

EPFL2018

Gene expression analysis of metastases and IL-1R1 characterization in a NALP3 mouse model

Heidi Fournier

Tumor microenvironment contributes strongly to tumor evolution toward metastasis, a final stage in cancer progression. It provides essential clues to promote migration of cancer cells in metastatic sites. Moreover, inflammatory cells and immunomodulatory mediators present in the microenvironment are able to polarize the host immune response, thereby potentiating primary tumor development. The reciprocal and dynamic interactions between microenvironment and tumor cells orchestrate critical steps of evolution toward metastasis. To address the role of inflammation in tumor progression, a mouse model of downregulated inflammation was used: the NALP3 gene in these mice is knocked-out, causing a impaired processing of the two inflammatory cytokines Interleukin-1[beta] and IL-18 which are essential for the recruitment and activation of immune cells. In this case, a decrease in tumor growth and metastasis was observed in previous studies, leading us to investigate the molecular and cellular interactions of tumor and immune cells in inflammatory and non-inflammatory contexts. Gene expression analysis was performed on two steps of mouse tumor cells: the B16-F10 melanoma cells seem to be more dependent on the immune cells recruitment to metastasize in vivo, while the Lewis Lung Carcinomas cells showed a quite equivalent growth in both wild-type or NALP3 knock-out mice. Different techniques were used to do so, such as standard in vitro assays and mRNA expression analyses, and in vivo tests with extraction of tumoral mRNA by Laser Capture Microdissection. Gene expression analyses of tumor cells were performed to address the influence of the inflammatory background. Comparison of these two gene expression profiles may reveal genes related to the specific reactive inflammatory response surrounding the given metastases. Another point that was investigated was the importance of the IL-1R1, receptor of interleukin-1. Since it represents the counterpart of IL-1[beta] signaling, its expression by immune and tumor cells may correlate with degree of tumor growth and invasion. In vitro and in vivo assays allowed better understanding the importance of this receptor. While a downregulation of this receptor impairs proliferation of in vitro cell cultures, at the in vivo level, the number of metastases is decreased too. These results provide potential clues indicating the important role played by the inflammatory cells, and how they can support and promote tumor progression, in particular through the expression of NALP3. The adaptation mechanisms of tumor cells to their microenvironment were also assessed, opening different insights for targeting the tumor itself as well as the inflammatory microenvironment.

2011