Defects in T-cell-mediated immunity to influenza virus in murine Wiskott-Aldrich syndrome are corrected by oncoretroviral vector-mediated gene transfer into repopulating hematopoietic cells

The Wiskott-Aldrich syndrome (WAS) is an X-linked disorder characterized by immune dysfunction, thrombocytopenia, and eczema. We used a murine model created by knockout of the WAS protein gene (WASP) to evaluate the potential of gene therapy for WAS. Lethally irradiated, male WASP ^- animals that received transplants of mixtures of wild type (WT) and WASP ^- bone marrow cells demonstrated enrichment of WT cells in the lymphoid and myeloid lineages with a progressive increase in the proportion of WT T-lymphoid and B-lymphoid cells. WASP ^- mice had a defective secondary T-cell response to influenza virus which was normalized in animals that received transplants of 35% or more WT cells. The WASP gene was inserted into WASP ^- bone marrow cells with a bicistronic oncoretroviral vector also encoding green fluorescent protein (GFP), followed by transplantation into irradiated male WASP ^- recipients. There was a selective advantage for gene-corrected cells in multiple lineages. Animals with higher proportions of GFP ⁺ T cells showed normalization of their lymphocyte counts. Gene-corrected, blood T cells exhibited full and partial correction, respectively, of their defective proliferative and cytokine secretory responses to in vitro T-cell-receptor stimulation. The defective secondary T-cell response to influenza virus was also improved in gene-corrected animals.