In patients with renal involvement, the proliferative activity of cMo, APC, and CXCR5− DNB was significantly elevated (rash+: 0.869%, rash‐: 0.280%, P = 0.00136; rash+: 0.282%, rash‐: 0.168%, P = 0.00112; and rash+: 0.138%, rash‐: 0.060%, P = 0.00083, respectively). Here, MOS is linked to exanthem.