CD4 and systemic lupus erythematosus: We acknowledge the limitations of our study as follows: 1) Only four markers (i.e. CD3, CD4, gp130 and IL-12Rβ2) to define the T cell subsets without including markers to identify Tregs and Bregs that produce IL-35, as well as their subpopulations particularly Tregs without functional suppressive capacity typically characterized by FOXP3+Helios─ expression (29, 58, 65); 2) We did not include a viability dye to distinguish dead cells; 3) Our cohort of healthy controls were not completely matched for age and gender with SLE patients.