CD19 and systemic lupus erythematosus: At a fundamental level, the co-culture of CD4+CD25+CD127low UCB-Tregs with SLE-PBMC shifts the dominance of CD8+ Teffs and CD19+ lupus B cells towards the CD4+CD25+CD127low Treg phenotype and CD4+CD8+ dual expressing T cells, which have been shown to have a suppressive effect on the production of autoantibodies including anti-dsDNA Ab in SLE (30).