Transfer of Immunity to Sarcoma I Homo- grafts in Newborn Mice I, 2

SUMMARY-Immunity to Sarcoma I (Sal) was readily transferred to newborn C57BL/6Ks mice from mothers that had been either actively immunized with live tumor or passively immunized with hyperimmune serum or hyperimmune cell-free ascitic Ruid containing anti-Sal antibody. The transfer of immunity to the newborn was most effectively demonstrated with a low challenge dose of 1,000 tumor cells given intraperitoneally. Foster-nursing experiments indicated that the immunity of the newborn offspring of immune mothers was acquired principally via the lacteal route. The development of Sal tumors was also prevented when the hyperimmune serum or ascitic Ruid was introduced directly into newborn mice. These results indicated that acquired maternal immunity transmitted to the newborn results from humoral antibody. Adult C57BL/6Ks mice rendered immuno-logically incompetent by X irradiation were likewise protected by hyperim-mune serum against small challenge doses of tumor cells. Serum and cell-free ascitic Ruid derived from these animals during primary rejection o