Effects of cryopreservation and irradiation on the donor leukocytes before transfers. The procedures of cryopreserving and irradiating donor leukocytes were described in the section of "materials and methods". After each adoptive transfer the groups were challenged with 1 × 106 S180. The percent survival after the S180 challenges is shown. The untreated controls for both groups are 100% survival. The cryopreserved leukocytes also result in 100% survival while the leukocytes irradiated at 25 Gray results in 38% survival.