• Survival rate at one year post-transplantation. T cell reconstitution: proliferative response to Tetanus Toxoid of greater than ten-fold. [ Time Frame: One year post-transplantation. ] [ Designated as safety issue: Yes ]
  

• 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. For patients with a severe T cell defect, the PI has shown that thymus transplantation is safe and efficacious under other clinical protocols. 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 receive human postnatal cultured thymus tissue transplants. Thymus tissue that would otherwise be discarded is transplanted into DiGeorge subjects in the operating room. At the time of transplantation, a skin biopsy is obtained look for any preexisting T cells. After transplantation, subjects are followed by routine research immune evaluations, using blood samples obtained every 2-4 weeks. At approximately 2-3 months post-transplantation subjects undergo an open biopsy of the allograft. The biopsy is done under general anesthesia in the operating room. At the time of the graft biopsy, another skin biopsy is 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.