To detect differences in the differentiation of Tregs/Tresps between healthy volunteers and SLE patients, we estimated the percentages of RTE and MN Tregs/Tresps, as well as CD31+ memory and CD31− memory-Tregs/Tresps within the total Treg/Tresp pool with age in both study groups. This evidence concerns the gene PECAM1 and systemic lupus erythematosus.