CTLA4 and systemic lupus erythematosus: Concurrently, CTLA4-expressing naïve and memory non-Treg CD4+ T effector cells were significantly reduced in adult-onset SLE compared to healthy (naïve: 1.61 [0.85-2.63]; 4.65 [3.2-7.18], p<0.0001; memory: 0.54 [0.34-0.79]; 1.46 [1.00-2.06], p<0.0001).