Like other immune-suppressive components of the Treg exosome, which are produced in a latent form, exosomal GARP/TGFβ:LAP produced by allo-specific regulatory T cells undergoes either immediate activation (1° suppression) or internalization by naive T cells, followed by surface reexpression and subsequent activation (2°), to become suppressive. Our results imply a membrane-associated form of TGFβ:LAP that, like exosomal IL35, can target "bystander" lymphocytes. This new finding implicates exosomal TGFβ:LAP along with Treg-derived GARP as part of the infectious tolerance network.