NZB/W is a murine model for lupus nephritis, and when these mice were treated with anti–PD-1–depleting Abs, the animals presented with less severe nephritis secondary to a reduction in the number of the CD4 T-cells that expressed PD-1 together with enhancement in the function of CD4 TREG (Wong et al., 2010). Here, CD4 is linked to lupus nephritis.