Staining for regulatory T cells on PBMCs isolated before and after AAV-2-hF.IX hepatic gene transfer. Each line represents one individual animal. y-axis shows the percent of CD4⁺CD25⁺FoxP3⁺ T cells. Cells were gated on CD4⁺CD25^hi and analyzed for FoxP3. (A) Animals receiving only the AAV vector with no IS. (B) Animals receiving both the vector and an IS regimen consisting of MMF, sirolimus, and daclizumab. (C) Animals receiving the vector and MMF and sirolimus.