Abstract
Chronic granulomatous disease (CGD) can result from any of four single gene defects involving components of the superoxide (O2-.)-generating phagocyte NADPH oxidase (phox). The phox transmembrane flavocytochrome b558 is composed of two peptides, gp91phox and p22phox. Mutations of gp91phox cause X-linked CGD, whereas mutations of p22phox cause one of the three autosomal recessive forms of CGD. We used the Maloney leukemia virus-based MFG retrovirus vector to produce replication defective retroviruses encoding gp91phox or p22phox. To maximize viral titer MFG retroviruses do not contain internal promoter or resistance elements. Epstein-Barr virus transformed B-lymphocyte cell lines (EBV- B) derived from normal individuals contain phox components and produce O2-., whereas those derived from CGD patients show the CGD defect. Transduction of gp91phox or p22phox-deficient CGD EBV-B lines resulted in correction of O2-. production from a barely detectable baseline to an average 7.2% and 13.8% of normal control, respectively, without any selective regimen to enrich for transduced cells. CD34+ hematopoietic progenitor cells, the therapeutic target for gene therapy of CGD, were isolated from peripheral blood of CGD patients, transduced with MFG- phox retroviruses, and differentiated in culture to mature phagocytes. Transduction of progenitors corrected the gp91phox (seven patients) and p22phox (two patients) CGD phagocyte oxidase defect to 2.5% and 4.9% of normal O2-. production, respectively, representing an 87-fold and 161- fold increase. These studies show correction of flavocytochrome b558- deficient CGD in primary hematopoietic progenitors, providing a basis for development of gene therapy for the X-linked gp91phox and autosomal p22phox-deficient forms of CGD.
