Establishment and maintenance of a human glioma transplanted serially to hereditary asplenic-athymic (lasat) mice.

A tumor line in asplenic-athymic (lasat) mice designated KNS-GL-2 was established from a recurrent anaplastic astrocytoma of the cerebrum in a 15-year-old boy (NS761072). The tumor line increased in terms of the rate of tumor take and growth with serial passage, forming a nodular appearance and massive intratumoral hemorrhage at the third generation. Microscopically, tumors developed in lasat mice wee similar to the original tumor and consisted of cells with round and oval nuclei and a clear cytoplasm, which was positive for S-100 and GFA proteins by the immunoperoxidase method. Large clusters of tumor cells with dark scanty cytoplasm seen at the third generation lost their astrocytic appearance and were negative for both S-100 and GFA proteins. This was considered to be evidence for dedifferentiation or malignant transformation. There was a scattering of tumor cells with clear cytoplasm in these clusters, with a positive reaction to S-100 protein. It was possible that tumor cells dedifferentiated during serial passage but still retained the potential to differentiate into astrocytes.