Homograft tolerance in mice: use of urethan and sublethal irradiation.

Adult mice [CBA/J (H-2(k))], which received either a single sublethal dose of x-radiation (500 rad) or urethan plus 500 rad, were given intravenous injections of C3H/HeJ (H-2(k)) spleen or bone marrow cells (18 to 42 x 10(6) cells per mouse) or both, for 3 days. C3H/HeJ tail-skin homografts were retained (over 130 days) by these mice, whereas BALB/cJ (H-2(d)) homografts all were rejected within 33 days. Similarly irradiated or urethan-treated controls (or controls treated with a combination of both), which did not receive C3H cells, rejected both homografts. Specific homograft tolerance is induced in adult mice by this procedure.