[Effect of T-activin and hydrocortisone on transplantation immunity]

The response of thymectomized and lethally irradiated adult CBA mice to C57Bl/6 mouse skin grafts was studied after recipient protection by syngeneic bone marrow treated in vitro with T-activin, an active factor of the calf thymus with a molecular weight from 1500 to 6000 dalton, and with hydrocortisone for 30 min at 37 degrees C. Bone marrow cells treated with T-activin coupled with hydrocortisone or with T-activin alone induced the development of transplantation immunity in 85 and 80% of the recipients, respectively. Syngeneic bone marrow cells from hydrocortisone-treated donors recovered transplantation immunity in all the donors.