EXPRESSION OF TYPE-I INTERFERON RECEPTOR IN SOLID TUMORS OF CHILDHOOD

Interferon alpha (IFN alpha) is used as an antineoplastic agent both i n hematopoietic malignancies and in solid tumors, because of its immun omodulatory action and direct antitumor activity. IFN alpha binds to s pecific cell-surface receptors that mediate its biologic activity. We studied the expression of IFN alpha receptors in pediatric solid tumor s by use of the monoclonal antibody IFNaR3, which specifically recogni zes the alpha subunit of the IFN Type I receptor. In three cell lines derived from those tumors, we determined the structure of the receptor s by affinity cross-linking and immunoprecipitation techniques, and we determined their ability to mediate an antiproliferative effect. All of the tumor specimens studied by immunocytochemical analysis, includi ng neuroblastomas, primitive neuroectodermal tumors, and rhabdomyosarc omas, stained positive for the IFN alpha receptor antibody, although i n some cases immunoreactivity was weak. The three cell Lines, derived from a neuroblastoma, a primitive neuroectodermal tumor, and a Ewing's sarcoma, respectively, showed the same pattern of IFN alpha receptor expression, both by affinity crosslinking and immunoprecipitation assa ys. Treatment with IFN alpha of those cell lines induces growth inhibi tion in vitro. These results suggest that IFN Type I receptor might be expressed in most solid tumors of childhood and that its structure is identical to the receptor expressed by the majority of hematologic ma lignancies.