Alymphatic skin islands: a murine model

Regional lymph node x-radiation suppresses allograft rejection

We studied the effect of a single dose of x-radiation given to the regional lymph nodes on allograft rejection. Our model was an A-strain tumor, transplanted to C57B1/6, DBA/2, and C57B1/6 x CBA hosts. Irradiation (1,000 rad) of the regional lymph nodes inhibited graft rejection, as judged by increased tumor growth, slower rejection, and, in the case of DBA/2 mice, by fewer regressions; irradiation of the contralateral lymph nodes did not have this effect. The mechanism of immunosuppression appeared to be B-cell independent, since immunosuppression could be induced by regional x-radiation as readily in B-cell deficient mice as in normal mice. The suppression was critically time-dependent, viz, irradiation before, or 6 or more days after, tumor graft was without significant effect. Treatment of the allogeneic host with cyclophosphamide several days before grafting, so as to reduce T-suppressor cells, attenuated the immunosuppression of regional x-radiation.

Electrocoagulation induced immunity--an explanation for regression of neuroblastoma

Electrocoagulation of tumor potentiates the host's antitumor immune response. Utilizing a murine neuroblastoma system and comparing surgical excision versus electrocoagulation we have demonstrated that electrocoagulation potentiates the immunogenicity of the neuroblastoma, potentiates the host antitumor immune response to residual primary tumor, and potentiates the host antitumor immune response to distant autochthonous neuroblastoma. These data suggest that such a heightened antitumor response might account for spontaneous regression of massive clinical neuroblastomas treated by electrocoagulation, and they suggest that electrococoagulation may be useful as a treatment modality for cytoreductive neuroblastoma surgery.