Cells of the innate immune system initiate the adaptive immune response to infections and inflammatory stimuli. In order to efficiently mount a tailored T cell response three signals are required: MHC:TCR stimulation, co-stimulation and cytokines. Dendritic cells, macrophages and innate lymphoid cells are fully equipped to provide all three signals. Our research focuses on the cell-specific role of costimulatory molecules with activating and inhibiting function - and what regulates their expression.
One of these molecules is programmed death ligand 1 (PD-L1, CD274, B7-H1), which interacts with programmed cell death protein 1 (PD-1, CD279) on activated T cells. Classically, this protein-protein-interaction leads to the inhibition of the T cell response. Blockade with so-called immune checkpoint inhibitors re-activates T cells. In the context of Th1- and Th17-responses, such as cancer and autoimmunity, its inhibitory function is very well studied but the knowledge on the impact on other T cell subsets remains incomplete.