PDCD1 and B-cell chronic lymphocytic leukemia: This confirmed an enrichment of physical interactions between CD4 TREG and CD8 PD1+ T cells as well as CD4 PD1+ or PD1- T cells (Fig. 2C, D, Supplementary Fig. 3D) suggesting that TREG limit the activity of CD4 and CD8 T cells in the CLL LNs.