CD4 and autoimmune disease: The mechanism by which checkpoint inhibitors trigger autoimmunity is incompletely understood, and may be related to dysregulation of a preexisting immune response to self-antigens, which had been formerly contained by immune checkpoints.32 Additionally, proliferation of effector T cells combined with impairment in regulatory T cells and dysfunctional interactions with antigen presenting cells may play a role.33 Interestingly, while the 2 autoimmune disorders we presented have very different clinical manifestations, both involve CD4+ T cells.