Immune‐depressive effect of urethan on the homograft response in mice

Abstract

The effect of a multiple administration of urethan on cellular immunity was tested in young mice. Two different systems were used, the rejection of coisogenic and allogeneic skin grafts and the growth of an antigenic 3‐methylcholanthrene (MCA)‐induced sarcoma isograft. The urethan immune depression appears to be confined to the reaction against weak histocompatibility antigens, since the drug was able to prolong the C57BL/6 male to female skin graft rejection and to impair the immunological capacity in mice transplanted with an isogenic, highly antigenic, MCA‐induced sarcoma. On the contrary, the urethan was ineffective when tested in a strong antigenic difference. The implications for the possible mechanism of urethan carcinogenesis are discussed.