When the Treg definition included “FOXP3-positive” cells, the proportions did not differ between SLE patients and controls [−0.042, (−0.548, 0.632), p = 0.889, I2 = 96.6%]; this was the case when Tregs were defined as either “CD25low/−FOXP3+” or “CD25high/+FOXP3+” cells. Here, FOXP3 is linked to systemic lupus erythematosus.