The contribution of individual TCR signaling components to thymic selection (P4540)

Abstract

Abstract In the thymus, T cell progenitors undergo an extensive selection program that shapes the repertoire of T cell receptors to ensure that mature T cells released into the periphery are tolerant to peptides derived from self proteins but able to recognize foreign peptide antigens. The engagement of the T cell receptor on a developing thymocyte triggers the formation of a proximal signaling complex at the plasma membrane and initiates a calcium signal, which together activate multiple downstream signaling cascades crucial for the thymocyte’s survival and maturation. One of the major signaling pathways initiated is the Ras/MAP kinase cascade, which plays an essential role during the positive selection of thymocytes. As thymic positive selection does not occur efficiently in 2-dimensional co-cultures, we are using a thymic slice preparation that provides the 3-dimensional stromal architecture of the thymus. We aim to study the signaling properties of MHC class I-restricted T cell receptor transgenic CD4+CD8+ thymocytes during positive selection either by flow cytometry or by two-photon laser scanning microscopy. We are using pharmacological inhibitors to understand the contribution of individual T cell receptor signaling components to positive selection. We hope to dissect both their longer-term effect on the thymocytes’ development, as well as their interconnection and potential compensatory mechanisms.