CD4 and T-cell leukemia: Positioned at the center of the SN-Treg signaling network, IL16 can attract CD4+ T cells and inhibit CD3-mediated lymphocyte activation and proliferation (Zhang & Xu, 2002), and recombinant human IL16 has shown inhibitory effects on the growth of human T-cell leukemia Jurkat cells (Zhang & Xu, 2002).