Cells in the body can communicate through protein-protein interactions. This process is essential for immune responses against viruses and cancer, but also in autoimmunity. In my lab, we recently discovered that certain glycolipids on the surface of cells can shield proteins from their communication partners. We showed that this shielding determines the strength of responses by T cells of the immune system. The specific subclass of glycolipids is highly abundant on acute leukemia cells. In this proposal, we will investigate the mechanism behind the interplay between glycolipids and proteins. Furthermore, we will determine the role of leukemia derived glycolipids for the onset and quality of T cell driven immune responses in vivo. I expect to provide novel insights in regulation of anti-tumor T cell responses which may also be relevant to the fields of infection and autoimmunity. Our findings may further provide targets for therapeutic modulation of T cell responses.