Figure 1: Mechanisms of autologous NK cell activation by paediatric brain tumour cells. Activation of NK cells results in the release of proinflammatory cytokines and cytolytic granules. In a healthy cell, interactions of self MHC-I with NK cell inhibitory receptors result in selftolerance. A Self MHC-I expression can be downregulated in some tumour cells, the absence of which lifts the natural inhibition of autologous NK cells, resulting in tumour cell lysis. B Activating ligands upregulated on tumour cells provides a strong activating signal to autologous NK cells, allowing the NK cell to overcome inhibition. Adapted from Vivier et al. and Kumar & McNerney [42, 44].