As CD4+CD40L+ T cells have been shown to cluster near Ki-67+ CLL cells within LN tissue biopsies,8 we hypothesized that improved cell-cell interactions in a 3D conformation aid CLL cells to proliferate and evade cell death.3,9 First, we aimed to incorporate T cells as a source of physiological CD40L by recapitulating the composition of CLL and T cells in the CLL LN. This evidence concerns the gene MKI67 and B-cell chronic lymphocytic leukemia.