No apparent toxicities and no relevant changes in blood counts, serum biochemistry, or liver histology were observed in animals treated with AAV-IA despite the fact that serum IFNα was present at high levels at the time of sacrifice (Supporting Information Fig.5 and Supporting Information Table 2). Six days after injecting pIFN, pIA, or pApo

(a plasmid encoding apolipoprotein A-I used as a control), we analyzed the number and activation status (as estimated by the percentage of CD69+ cells) of immunocytes in the spleen. The percentage of dendritic cells, macrophages, B cells, and natural killer (NK) cells positive for CD69 were similar in mice treated with pIFN and pIA (Supporting Information Fig. 5). However, administration of pIA caused a greater increase in the total number of splenocytes and in the percentage BMN 673 ic50 of CD8+ and CD4+ T cells expressing CD69 than when injecting pIFN (Fig. 4A). In vivo killing assays against a BALB/c immunodominant GDC0068 β-galactosidase epitope were

performed in mice which, 7 days previously, received a hydrodynamic coinjection of a plasmid encoding LacZ together with pIFN or pIA or pApo. These studies showed that the group treated with pIA exhibited a cytolytic activity significantly greater than the other two groups (Fig. 4A). We also observed differences between pIFN and pIA in the induction of protective immunity in a murine model of vaccination against CT-26 colon cancer. Vaccination was performed by subcutaneous administration of the AH-1 peptide (which corresponds to the tumor immunodominant epitope) 24 hours after hydrodynamic injection of either pApo, pIFN, or pIA. Ten days later, the animals received a subcutaneous injection of 5 × 106 CT-26 cells in the right flank. We observed that adjuvant treatment with pIA, but not with pIFN, was associated with significant protection against tumor growth as compared to the control group given pApo (Fig. 4B). In additional experiments, the immunological check details changes induced

by pIA and pALF were compared. The hydrodynamic administration of pIA or pALF caused a similar rise in the number of splenocytes and in the percentage of splenic CD69+CD4+ and CD69+CD8+ cells (Fig. 4C; Supporting Information Fig. 6). Because pIA overrides pIFN but is equal to pALF in increasing the number and activation of splenocytes, it seems possible that these phenomena might be related to the prolonged persistence of both IA and albumin-IFNα in the circulation. However, IA largely surpassed albumin-IFNα in its ability to stimulate cytotoxic T cell responses, as demonstrated by in vivo killing assay against the immunodominant β-galactosidase epitope (Fig. 4C). As SR-BI is a potential receptor for the ApoA-I moiety of IA, we wished to investigate whether the interaction of this molecule with SR-BI could mediate the potent immunostimulatory effects exhibited by IA.