S1PR1 has well established roles in T cell trafficking out of lymphoid tissue, it’s role for T cell egress from mucosal tissues is less well defined.14 Mice with S1PR1 deficient Treg develop autoimmunity, Treg display an activated phenotype prone to apoptosis.43 The functional role of endometrial S1PR1 Treg expression remains to be determined, and if the expression indicates a subset of Treg in PRPL which can exit the tissue. This evidence concerns the gene S1PR1 and Autoimmunity.