Described are antigen specific and antigen non-specific means of suppressing development of Type 1 Diabetes in a mammal through administration of exosomes, microvesicles or apoptotic bodies from monocytic lineage cells that have been reprogrammed by contact with mesenchymal stem cells and/or mesenchymal stem cell conditioned media. In one embodiment, the invention provides administration of exosomes that have been generated from monocytic cells that have been loaded with tolerogenic antigens and/or epitopes. In another embodiment the invention provides administration of allogeneic myeloid derived exosomes that are loaded with tolerogenic antigens. In another embodiment the invention provides means of stimulating exosome release in vivo from allogeneic cells that have been administered to the patient in need of treatment.