• Survival rate at one year post-transplantation. [ Time Frame: One year post-transplantation. ] [ Designated as safety issue: Yes ]
  
• T cell reconstitution: proliferative response to Tetanus Toxoid of greater than ten-fold. [ Time Frame: 1 year post-transplantation ] [ Designated as safety issue: No ]
  

• T cell responses to mitogens and T cell numbers [ Time Frame: Ongoing ] [ Designated as safety issue: No ]
  

There is no safe and effective treatment for DiGeorge syndrome and most patients die by the age of two. Complete DiGeorge syndrome is characterized by very low T cell or very low naïve T cell numbers. In this study, typical complete DiGeorge syndrome subjects received human postnatal cultured thymus tissue transplants. Thymus tissue that would otherwise be discarded was transplanted into DiGeorge subjects in the operating room. At the time of transplantation, a skin biopsy was obtained to look for any preexisting T cells. After transplantation, subjects were followed by routine research immune evaluations, using blood samples obtained every 2-4 weeks. At approximately 2-3 months post-transplantation subjects underwent an open biopsy of the allograft. The biopsy was done under general anesthesia in the operating room. At the time of the graft biopsy, another skin biopsy was obtained to look for clonal populations of T cells.

The protocol aims include: assessing thymopoiesis in the allograft biopsy; assessing immunoreconstitution of complete DiGeorge syndrome subjects after postnatal allogeneic thymus transplantation; assessing minimally invasive methods of assessing thymopoiesis (flow cytometry and polymerase chain reaction (PCR); assessing pre-transplant T cells which do not proliferate in response to mitogens (focusing on NK-T cells); and, assessing thymus transplantation safety and toxicity.