IL2 and Autoimmunity: However, DAC significantly impairs Treg cell expansion, and, possibly, activation-induced T cell apoptosis, both of which depend on IL-2 interacting with its high-affinity receptor on lymphoid lineage cells, and may largely explain the susceptibility of DAC HYP-treated patients to develop the severe secondary autoimmune disorders that resulted in its removal from clinical use in patients with RMS.