CD28 and central nervous system cancer: We formed neuro spheres from parental U251-IDH-R132H glioma clones characterized in our recent manuscript [30], with low and high PDL1 expression levels (at least 10 folds difference in PDL1 expression levels) and evaluated the outcome of tumor neuro spheres’ encounters with primary T cells (depleted from CD14 monocytes and stimulated with CD3/CD28 Diamagnetic beads).