A novel detection system for submicroscopic human metastases in athymic mice

We developed a sensitive assay system to accurately detect the amount of human tumor DNA, if present, in athymic mouse organs. Genomic DNA was prepared from a human lung carcinoma cell line and from athymic mouse lungs (tumor-bearing and non-tumor bearing). Mixtures and dilutions of extracted DNA were slot-blotted onto nylon filters and probed with labeled, human-specific Alu sequences. The equivalent of one human cell per 2000 mouse cells could be detected using this assay. This sensitive assay may now be used to confirm the presence or absence of human neoplasm metastases in the athymic mouse model system.