CD19+CD5+ CLL cells are greatly influenced by T cell-derived cytokines such as IL-1-alpha, IL-1-beta, IL-6, IL-7, IL-8, IL-10, IL-13, IFN-γ, and transforming growth factor (TGF)-β, which mediate interactions between B and T cells [25,26]. Here, TGFB1 is linked to B-cell chronic lymphocytic leukemia.