Abstract: A patient's acceptance of transplanted organs and tissues may be enhanced by treating donor specific blood with a suitable dose of ultraviolet radiation for an appropriate period of time, transfusing the irradiated blood into the patient during a suitable pretransplantation time period and then transplanting the organ or tissue into the subject. Acceptance of transplanted organs and tissues can also be enhanced by treating the organs or tissues to be transplanted with a suitable dose of ultraviolet radiation for an appropriate period of time and then transplanting the organ or tissue. Suitably irradiated donor specific blood, organs and tissues are preferred for use in transplantation.

Abstract: A patient's acceptance of a transplanted organ or tissue from a donor may be enhanced by irradiating donor-specific blood with ultraviolet-B radiation at a dosage of less than 1000 J/M.sup.2 so as to render the blood capable of inducing donor-specific immunological unresponsiveness in the patient, transfusing the irradiated, donor-specific blood into the patient prior to transplanting the organ or tissue into the patient to enhance subsequent acceptance of the organ or tissue by the patient, and thereafter transplanting the organ or tissue into the subject.A patient's acceptance of transplanted organs and tissues can also be enhanced by removing the organ or tissue from the donor and irradiating the organ or tissue to be transplanted with ultraviolet-B radiation at a dosage of less than 1000 J/m.sup.2 so as to enhance acceptance of the transplanted organ or tissue and then transplanting the irradiated organ or tissue into patient.