HLA Class II Matched Parathyroid Allotransplantation: 5-Year Follow-Up of Panel Reactive Antibody and Crossmatch

Parathyroid allotransplantation has been a curative option for patients with severe permanent hypoparathyroidism for more than 50 years. Despite advancements, parathyroid allotransplant outcomes still depend on reliable parameters, including HLA-allele matching criteria. Here, we report 2 cases of parathyroid allotransplant between ABO/Rh-compatible donors and recipients with HLA-DR and HLA-DQ allele match.

The recipients, aged 39 and 43 years, had been on the parathyroid allotransplant wait list for 5 years. Both experienced persistent hypocalcemia-related symptoms despite daily supplementation with intensive supplementation therapy. Ineffectiveness and side effects of increasing supplementation doses resulted in parathyroid allotransplant. The living unrelated donors, both with chronic kidney disease, underwent subtotal parathyroidectomy. Half of the retrieved parathyroid tissue was cryopreserved. After histopathological approval, parathyroid allotransplant was performed laparoscopically by transplanting parathyroid cells over the omentum. Preoperative assessments were negative, including panel reactive antibody and T-cell/B-cell crossmatch tests. Postoperatively, recipients received 10 mg/day methylprednisolone for 1 month. Outcomes were monitored for 5 years.

After parathyroid allotransplant, recipient 1 showed reduced symptoms and medication requirements, decreasing to 600 mg calcium and 400 IU cholecalciferol daily, which were maintained for 4 years. However, by year 5, oral supplementation returned to initial levels. Recipient 2 exhibited similar improvements, with symptoms relieved and oral supplementation halved to half doses. Serum calcium levels at year 5 were 8.6 mg/dL and 9.0 mg/dL for recipients 1 and 2, respectively.

Our cases, to our knowledge, are the first to document panel-reactive antibody and T-cell and B-cell crossmatch-negative parathyroid allotransplant with HLA class II allele matching. HLA matching may enhance survival rates posttransplant. Only parathyroid cells were transplanted in both cases, and recipients received short-term immunosuppression with steroids. Further studies with larger cohorts are needed to establish the relationship between HLA allele matching and posttransplant survival rates.