RETROVIRAL-MEDIATED GENE-TRANSFER OF GP91(PHOX) INTO BONE-MARROW CELLS RESCUES DEFECT IN HOST-DEFENSE AGAINST ASPERGILLUS-FUMIGATUS IN MURINE X-LINKED CHRONIC GRANULOMATOUS-DISEASE

The X-lnked form of chronic granulomatous disease (X-CGD), an inherite d deficiency of the respiratory burst oxidase, results from mutations in the X-linked gene for gp91(phox), the larger subunit of the oxidase cytochrome b. The goal of this study was to evaluate the impact of re troviral-mediated gene transfer of gp91(phox) on host defense against Aspergillus fumigatus in a murine model of X-CGD. Retrovirus vectors c onstructed using the murine stem cell virus (MSCV) backbone were used for gene transfer of the gp91(phox) cDNA into murine X-CGD bone marrow cells. Transduced cells were transplanted into lethally irradiated sy ngeneic X-CGD mice. After hematologic recovery, superoxide production, as monitored by the nitroblue tetrazolium (NET) test, was detected in up to approximate to 80% of peripheral blood neutrophils for at least 28 to 35 weeks after transplantation. Neutrophil expression of recomb inant gp91(phox) and superoxide production were significantly less tha n wild-type neutrophils. However, 9 of 9 mice with approximate to 50% to 80% NBT+ neutrophils after gene transfer did not develop lung disea se after respiratory challenge with 150 to 500 A fumigatus spores, dos es that produced disease in 16 of 16 control X-CGD mice. In X-CGD mice transplanted with mixtures of wild-type and X-CGD bone marrow, greate r than or equal to 5% wild-type neutrophils were required for protecti on against A fumigatus challenge. These data suggest that expression o f even low levels of recombinant gp91(phox) can substantially improve phagocyte function in X-CGD, although correction of very small percent age of phagocytes may not be sufficient for protection against A fumig atus. (C) 1997 by The American Society of Hematology.