Matched Related and Unrelated Donor Hematopoietic Stem Cell Transplantation for DOCK8 Deficiency.

AbstractWe performed allogeneic hematopoietic stem cell transplantation in 6 patients with mutations in the dedicator-of-cytokinesis-8 (DOCK8) gene using a myeloablative conditioning regimen consisting of busulfan 3.2 mg/kg/day i.v. for 4 days and fludarabine 40 mg/m2/day for 4 days. Three patients received allografts from matched related donors and 3 patients from matched unrelated donors. Two patients received peripheral blood stem cells and 4 patients bone marrow hematopoietic stem cells. Tacrolimus and short-course methotrexate on days 1, 3, 6, and 11 were used for graft-versus-host-disease (GVHD) prophylaxis. All 6 patients are alive at a median follow-up of 22.5 months (range, 14 to 35). All patients achieved rapid and high levels of donor engraftment and complete reversal of the clinical and immunologic phenotype. Adverse events consisted of acute skin GVHD in 2 patients and post-transplant pulmonary infiltrates in a patient with extensive bronchiectasis pretransplant. Thus, a uniform myeloablative conditioning regimen followed by allogeneic hematopoietic stem cell transplantation in DOCK8 deficiency results in reconstitution of immunologic function and reversal of the clinical phenotype with a low incidence of regimen-related toxicity

Dual proteolytic pathways govern glycolysis and immune competence.

Proteasomes and lysosomes constitute the major cellular systems that catabolize proteins to recycle free amino acids for energy and new protein synthesis. Tripeptidyl peptidase II (TPPII) is a large cytosolic proteolytic complex that functions in tandem with the proteasome-ubiquitin protein degradation pathway. We found that autosomal recessive TPP2 mutations cause recurrent infections, autoimmunity, and neurodevelopmental delay in humans. We show that a major function of TPPII in mammalian cells is to maintain amino acid levels and that TPPII-deficient cells compensate by increasing lysosome number and proteolytic activity. However, the overabundant lysosomes derange cellular metabolism by consuming the key glycolytic enzyme hexokinase-2 through chaperone-mediated autophagy. This reduces glycolysis and impairs the production of effector cytokines, including IFN-γ and IL-1β. Thus, TPPII controls the balance between intracellular amino acid availability, lysosome number, and glycolysis, which is vital for adaptive and innate immunity and neurodevelopmental health