Abstract
Natural IgM inhibits gene transfer by adenovirus type 5 (Ad5) vectors. We show that polyreactive natural IgM antibodies bind to Ad5 and that inhibition of liver transduction by IgM depends on Kupffer cells. By manipulating IgM concentration in vivo, we demonstrate that IgM inhibits liver transduction in a concentration-dependent manner. We further show that differences in natural IgM between BALB/c and C57BL/6 mice contribute to lower efficiency of Ad5 gene transfer in BALB/c mice.