Minitransplant Using Repeated Unrelated Donor Lymphocyte Infusions as a Treatment of Immunodeficiency in Complete DiGeorge Syndrome.

Complete DiGeorge syndrome (DGS) is a congenital disorder characterized by developmental defects of the heart, parathyroid glands and thymus associated with T-cell deficiency. Peripheral expansion of mature donor T cells thus represents a rational therapy. We present an infant with complete DGS treated with unrelated donor lymphocyte infusion (DLI). A Caucasian boy with multiple anomalies including choanal and esophageal atresia, congenital heart defects, retinal coloboma, tracheobronchomalacia, and gastroesofageal reflux was diagnosed with complete DGS at the age of 2 months. Lymphocyte subsets showed absence of T cells (0.0021x10⁶/mL T cells, 1.9x10⁶/mL lymphocytes at diagnosis) with no response to mitogens and absence of thymus. Microdeletion 22q11 was not found. During first 7 months of age he required long-term ventilation. At the same time, he suffered recurrent infections and sepsis. He had no sibling and no fully matched unrelated donor was available. At the age of six months the first dose of DLI (1x10⁶/kg CD3+; 2x10⁵/kg CD34+) was administered from an unrelated donor (mismatched for B and Cw alleles) with no conditioning regimen and no graft versus host disease (GVHD) prophylaxis. Although several units of blood products were not irradiated by mistake (9 in total, 8 times prior the 1st DLI), there was no proof of their engraftment. On day +10 after first DLI the boy developed severe isolated skin acute GVHD (stage 3–4) complicated with sepsis, cardiopulmonary instability and capillary leak syndrome, treated with antithymocyte globulin (rATG), cyclosporin A (CsA) and corticosteroids with a complete resolution of GVHD. Ventilation support was terminated at the age of 7 months. On day +36 after 1st DLI he was given the 2nd DLI (0.9x10⁶/kg CD3+) from the same donor with no conditioning and with GVHD prophylaxis consisting of continued CsA. Severe documented complications were EBV infection 4 weeks after application (peripheral expansion of CD8+ donor cells started, treated with CsA withdrawal and 2 doses of rituximab). Isolated cholestatic liver GVHD manifested 1 month after second DLI, progressed to stage 4 over 3 weeks, successfully treated with corticosteroids, CsA and rATG. Since day+19 after 1st DLI, the donor genotype was documented in FACS-sorted T cells. Response to mitogens appeared and is now comparable to healthy controls. We used 7-color flow cytometry in subsequent specimens (three at the time of this abstract submission) to specify the developmental stage of the engrafted T cells. Central memory (CD27^posCD45RA^neg) stages dominate in the peripheral blood CD4 and CD8 cells (64 to 81% and 52 to 95%, respectively), which was higher than in control blood. Effector memory cells are increased in CD4 subset but decreased in CD8, whereas naive cells are decreased or normal. The patient, age 13 months, is now 6 months after 2nd DLI still on immunosupression (CsA and steroids), slowly started to gain his developmental milestones. We believe that infusions of small doses of DLI from an unrelated donor represent an adequate therapy for complete DiGeorge syndrome. Supported by NI 7410-3, MSM0021620812