Effects of intralesional interferon on neuroblastoma: changes in histology and DNA content distribution of tumor masses.

Local injections of interferon, 30 X 10(4) IU, ten times, were found to reduce masses of neuroblastoma. Histologic findings and nuclear DNA measurements of cells from tumors in which interferon has been injected compared with cells from tumors that did not receive injections demonstrated that the reduction of neuroblastoma masses by interferon did not depend on increased cell differentiation or on interruption of tumor cell production. Although the mechanism of interferon's action on reducing neuroblastoma is unknown, the disappearance of tumor cells may be caused by high levels of interferon in tumor tissues.