Characterization of micro RNAs (mir 146a, 10a and 34a) involved in the thymic epithelial cell development Autoimmune diseases occur when the body's immune system is unable to distinguish between self and non self antigens. The process by which the immune system is tolerant (does not trigger a response) to self antigens is called Immune tolerance. T lymphocytes are a group of white blood cells involved in cell mediated immunity. During the developmental stages, T lymphocytes undergo a series of positive and negative selection stages in order to encourage non auto reactive cells and exclude any auto reactive lymphocytes. These cells develop within the thymus which consists of medullary and cortical epithelial cells (mTEC/cTEC). These cells are vital to the selection process of the T lymphocytes and this is done be displaying a variety of promiscuously expressed tissue restrictive antigens on the m/c TEC cell surface and selectively weed out the auto reactive lymphocyte. The ability of m/c TEC cells to display these promiscuous antigens on its cell surface is critical to Immune tolerance process. Understanding the developmental process of these cells can shed some light into this. My host lab had identified putative micro RNAs that were suspected to be involved in the m/c TEC cell development. My project dealt with characterizing the putative micro RNAs. I hypothesized the increasing the expression of these micro RNAs in fetal thymic stem cells could lead to their differentiation in m/c TEC cell type. This could be tested using several RNA/Protein markers that confirm the epithelial cell type. For increasing the expression of micro RNAs I cloned it into a vector with a strong promoter and stably transected it into the undifferentiated cell line. This process yielded effective results but I am not at liberty to discuss them since it is unpublished material. The overall goal of this study is to understand the involvement of micro RNAs in the development of thymic cells.