This purified polyclonal antibody reacts with human ISG15 by western blot and ELISA. Although not tested, this antibody is likely functional in immunohistochemistry and immunoprecipitation. This antibody using the specified conditions may recognize other prominent intrinsic bands (UBLs or conjugates), especially at lower dilutions. An 18.5 kDa band corresponding to human ISG15 is detected. IFNa or IFNß stimulated HeLa cell lysates can be used as a positive control.