The immune system defends our body from pathogens, toxins and malignant cells. Cells and humoral components of the innate immune system recognize conserved structures, while those of the adaptive immune system identify specific antigens. For antigens to be able to stimulate the adaptive immune system, they have to be taken up and processed by innate mechanisms, e.g. autophagy. Subsequently, they can be presented to lymphocytes of the adaptive immune system, leading to the subsequent activation of these cells. Involved in this activation process is e.g. the transcription factor NF-kB. Once the antigen, i.e. the pathogen, is removed, the immune response is down-regulated again. Otherwise, constant activation of the immune cells might harm the body leading to autoimmune disease. Contributing to this down-regulation are regulatory T cells (Tregs) and cell death (e.g. apoptosis). For an ordered immune response, cells of the immune system communicate with each other and process the received signals via intracellular signaling cascades. Our work concentrates on these signaling pathways in immune cells, since they may be good targets for therapeutic intervention. Here, we focus on: