An investigation into the binding of CLEC-2 platelets with podoplanin under flow and Comparing the cell intrinsic and environmental effects of immunosenescence on B cell response

Lombard, Stephanie (2013). An investigation into the binding of CLEC-2 platelets with podoplanin under flow and Comparing the cell intrinsic and environmental effects of immunosenescence on B cell response. University of Birmingham. M.Res.

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Project 1: The interaction between C-type lectin receptor (CLEC-2) expressed on platelets and glycoprotein podoplanin on lymphatic endothelial cells is believed to be critical in the separation of the blood and lymphatic systems during development. There is therefore a keen interest in elucidating the mechanisms and effects of CLEC-2 -Podoplanin interaction which is not yet fully understood. The aim of this project is to examine the interation between these two proteins under conditions of blood flow. This is accomplished by the use of glass capillaries coated with the extracellular domain of podoplanin as an Fc fusion protein.

Human platelets were observed to adhere to Fc mPodoplanin and form aggregates at a low shear rate. This adhesion was inhibited by increasing the shear rate and the use of inhibitors such as the Src inhibitor dasatinib and integrin inhibitor Integrilin. Mouse platelets adhered to Fc mPodoplanin at the same low shear rates but aggregates did not form and dasatinib and integrilin had little effect on this adhesion. Mouse platelets adhered and formed aggregates at high shear rates and the ffect was proven to be a CLEC-2 mediated adhesion. It is a novel discovery that mouse platelets form large aggregates with podoplanin a high shear rates.

Project 2: There is a gradual deterioration of the immune system occurs by advancing age, which is known as immunosenescence. These effects can be seen in both aged humans and experimental animals. Immunosenescence is characterised by a decreased ability of B cells to produce high affinity antibodies. This decrease is believed to be caused by a number of factors including reduced effective T cell signalling to B cells, lack of somatic hypermutation (SHM) in germinal centre (GC) B cells, and/or an instrinsic shift in immunoglobulin repertoire (frasca et al., 2008). It is of key interest to discover if the reduced functionality of B cells is a cell intrinsic phenomenon or whether the environment, such as interaction with T cells and stromal cells, also plays a role. In this study B cells from old or young QM mice were transferred into old or young wild type recipients and a T cell dependent antibody response was induced. This study would suggest that the decline in humoral immune system is not B cell intrinsic problem but more likely to be due to problems in the aged environment. It is unknown yet how this may be occurring but it may be due to the stromal environment or insufficient T cell help.

Type of Work: Thesis (Masters by Research > M.Res.)
Award Type: Masters by Research > M.Res.
College/Faculty: Colleges (2008 onwards) > College of Medical & Dental Sciences
School or Department: School of Immunity and Infection
Funders: None/not applicable
Subjects: Q Science > QR Microbiology > QR180 Immunology
R Medicine > R Medicine (General)


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