Transplantation of immunologically modified pancreatic tissue

The activation of an alloantigen reactive T cell requires alloantigen recognition and additional external signals provided by antigen presenting cells of host or donor antigen. Graft passenger leukocytes are capable of presenting alloantigen directly to recipient T cells and providing interleukin-1. Alternatively, shed alloantigen may be presented passively by recipient antigen presenting cells. Nearly all attempts to alter graft tissue immunogenicity prior to transplantation have focused on removing passenger cells. Attempts to modulate islet graft immunogenicity include conventional organ culture, high oxygen/high pressure culture, interim hosting, and treatment with ultraviolet irradiation, monoclonal antibodies and complement, and immunotoxins. While these techniques have been successful in rodent models, attempts to apply these methods to human islet transplants have been unsuccessful.