FUNCTIONAL CORRECTION OF NADPH OXIDASE ACTIVITY IN PATIENTS WITH CHRONIC GRANULOMATOUS-DISEASE BY RETROVIRUS-MEDIATED GENE-TRANSFER

Disfunctions of NADPH oxidase cause chronic granulomatous disease (CGD), a rare inherited disease that induces a profound predisposition to severe, recurrent, and often fatal infections. The complexity of the enzyme predicts that CGD is a very heterogeneous disease, both at clinical and genetic levels. The X-linked form of CGD is due to mutations in the CYBB gene, located in band Xp21 of the X-chromosome, coding for the b-subunit (gp91-phox) of cytochrome b558 of phagocytes. All the X-Linked CGD cases are characterized by undetectable or greatly reduced oxidase activity and are referred to as X910, when the gp91-phox protein is totally absent, or X91+ and X91-, when the protein is present in normal or reduced amount respectively. We have used EBV transformed B-lymphocytes derived from two patients affected by X910 CGD to test the genetic reconstitution of the gp91-phox defect by retroviral gene transfer. The results obtained confirm that functional correction of the disease can be achieved by this strategy. Successful transduction of peripheral blood hematopoietic precursors was also achieved by using the retroviral vector carrying the functional gp91-phox cDNA. The high efficiency of infection of the hematopoietic precursors together with the relevant rate of expression obtained in the present study provide further support for the utilization of this retroviral vector to correct the oxidase deficiency in the hematopoietic precursors of CGD patients. The data presented in this work indicate that functional correction of X-linked chronic granulomatous disease can be achieved by virus-mediated gene transfer. Also from the clinical point of view, it should be considered that the treatment of CGD by gene transfer in hematopoietic precursors has a strong rational basis, since the disease is manifested exclusively on the myelomonocytic cell lineages.