The effect of local irradiation on the immune response in mice. II.--Alterations due to low dose scattering.

The effect of localized irradiation given as single dose on the immune response of tumour-bearing mice was evaluated using the CRT. The tumour system (MBL2 on C57BL/6 females) was regularly lethal, although presence of CTL was demonstrated 15 days after transplantation (50,000 cells in the left hind limb). This T-dependent, antigen-specific cytotoxic activity observed on day 15 in the non-irradiated tumour-bearing group was abolished in the irradiated group (but not in the sham-irradiated group) and their CTL were incapable to mount a secondary response in MLTC-CML. The scattering of the 1,600 rad-single dose was sufficient to provoke this inhibition.