Since SCID-BEIGE mice lack T and B lymphocytes as well as functional natural killer (NK) cells, it is possible that the CCR4 + Mac-1 tumor cells were eliminated by h1567 through neutrophildependent ADCC as neutrophils are intact in SCID-BEIGE mice and they express FccRIIIA receptors which have been shown to mediated ADCC [22, 23] . Tumor sections were excised 21 days after AAV8 gene transfer and analyzed histologically for expression of Ly6G, a member of the Ly-6 family of glycosylphosphatidylinositol (GPI)-anchored proteins expressed on murine neutrophils [24, 25] . Immunostaining of tumors sections with neutrophil-specific Ly-6G mAb confirmed infiltration of neutrophils into tumors treated with AAV8-h1567 (Figure 2c , upper-left and middle panels) but not with AAV8-11A (Figure 2c , lower-left and right panels). Quantification of the neutrophil infiltration demonstrated a marked accumulation of Ly-6G+ staining cells only in the h1567 treated mice (Figure 2d) .