In contrast to 4-1BB eliciting potent effector T-cell function, 4-1BB signaling has also been shown to reduce T-cell-mediated autoimmune responses in a variety of mouse models, including EAE, and Lupus, through activation induced death or anergy induction in autoreactive CD4 T cells. Here, TNFRSF9 is linked to systemic lupus erythematosus.