PECAM1 and systemic lupus erythematosus: However, equal percentages of RTE Tregs, but significantly increased percentages of more differentiated Treg subsets (MN Tregs, CD31+ memory Tregs and CD31− memory Tregs) were detected within total CD4+ T cells of SLE patients compared with healthy controls, proposing a differentiation which rather increases Tregs than Tresps in SLE patients (Additional file 1: Figure S1).