Upon activation immune cells like macrophages undergo fundamental metabolic reprogramming, a process that is not completely understood so far. Emerging evidence highlights the role of cell organelles, their dynamics and stress responses as central players in cellular metabolism. To determine if organellar programmes contribute to the metabolic activation of macrophages, we performed an imaging-based organelle screen. We hereby identifed macrophage polarization to be associated with a distinct lysosomal programme, indicating a role for lysosomes in macrophage polarization. Thus, during my PhD I want to understand how lysosomes are affected by and contributing to the metabolic reprogramming and activation of macrophages and potentially other immune cells.