PECAM1 and systemic lupus erythematosus: In SLE remission patients, we found significantly decreased percentages of RTE-Tregs and MN-Tregs, but increased percentages of CD31−-memory-Tregs within both total ICOS+- and ICOS−-Tregs compared to healthy controls (Figure 1A,B), proposing an age-independent increased differentiation of both ICOS+- and ICOS−-RTE-Tregs via resting MN-Tregs into CD31−-memory-Tregs in these patients (Figure 1C,D).