A group of human tumor cell strains has been identified that is more sensitive to growth inhibition produced by human interferon than are other tumor cell strains or normal human fibroblasts. This group of tumor strains, designated the Mer-phenotype, shares a biochemical defect in DNA repair. These strains may prove useful as the basis for a rapid, sensitive, and reliable bioassay for antitumor activities of manufactured interferons. Results from Phase I research are expected to establish measures for inters feron inhibition of cell growth, colony forming ability, DNA synthesis, and ornithine decarboxylase activity in several Mer~strains. Phase II research will focus on the use of the assay in isolation and characterization of interferons from natural and recombinant DNA sources, and in the use of the Mer-phenotype as a marker for interferon sensitivity of human tumors. This research may be applied commercially in the preparation of interferon and medically in thetreatment of human cancer with interferon.National Cancer Institute (NCI)
