Fig. 4.

Reduced Immunogenicity of an Immunotoxin with 8 mutations in PE38 in 3 strains of mice. Immunotoxins containing native PE38 or mutant PE38 (8X mutant) were injected intravenously every 14 days into 3 different strains of mice. Specific antibody responses were measured by an ELISA, which only detects antibodies to conformational epitopes on the surface of the protein. Open circles show reactivity with native PE38 and closed circles with the mutant with 8X mutant. In all strains of mice the mutant was less immunogenic and less antigenic. Adapted from The Proceedings of the National Academy of Sciences of the United States of America [published 2008, Vol. 105, 11311–11316].