Parathyroid Gland Transplantation without Posttransplantation Immunosuppression

Abstract

RATIONALE: Determine if combined thymus and parathyroid gland transplantation in a patient with DiGeorge syndrome will result in function of both organs. METHODS: The patient had both athymia with a total T cell count of 29 cells/μL and profound hypoparathyroidism with a parathyroid hormone level below the limit of detection. Allogeneic postnatal cultured thymus and a maternal parathyroid gland were transplanted after conditioning with 3 doses of rabbit antithymocyte globulin. The mother, thymus donor, and patient had partial HLA matching. RESULTS: The parathyroid hormone level was normal when first tested on day +17 and has since remained normal. The patient weaned off all calcium supplementation. On day +139, she developed a bacterial infection of her central line, during which she maintained ionized calcium levels above 1.10 mmol/L without the requirement for calcium supplementation. At day +213, her ionized calcium levels remain within normal limits (1.24 mmol/L). Thymic function has been excellent. A thymus graft biopsy performed on day +80 showed evidence of thymopoiesis. Naïve T cells were detectable in the blood on day +86, with progressively increasing numbers over time (naïve CD4+ 114 cells/μL and naïve CD8+ 42 cells/μL on day +202). The total T cell count increased over time (258 cells/μL on day +202), as well. Normal PHA responses were seen on days +157 and +202. The patient did not require any posttransplantation immunosuppression. CONCLUSIONS: Parathyroid transplantation, when combined with thymus transplantation in this patient with complete DiGeorge syndrome, led to parathyroid function without posttransplantation immunosuppression.