Disclosed is a method for enhancing the immune function of mammals other than a human comprising a step of: administrating an amplified and activated lymphocyte as an effective ingredient, which is isolated from a mammal other than a human, to an allogeneic mammal which is different from the mammal from which the lymphocytes derive but belong to the same species as the mammal from which the lymphocytes derive, said activated lymphocytes include activated CD8 wherein the allogeneic mammal is a mammal whose leukocyte antigen is not identical to a leukocyte antigen of the mammal from which the tissues derive.
