Subclasses of anti-hFVIII IgG immunoglobulin in hemophilia A mice after naked plasmid transfer of pBS-HCRHPI-hFVIIIA with or without single agent immunosuppression. Titers of subclasses of IgG including IgG1, IgG2a, IgG2b, and IgG3 produced at 2 months following gene transfer were determined by IgG subclass-specific ELISA. All animals treated as described in Figure 1 (A-H) were tested, and their levels were averaged.