Radioimmunodetection of human glioma xenografts by radiolabelled monoclonal antibodies.

Radiolabelled monoclonal antibodies (131I-MUC 8-22, 131I-MUC 2-63) were used for external scintigraphy of human glioma xenografts. To induce transplantation tumors. 5 x 10(6) cells (85HG-66) of an in vitro established human malignant astrocytoma (N66/85) were inoculated s.c. in BALB/c-nu/nu mice. The labelling of the immunoglobulins with 131iodine was carried out according to the iodogen method, the nude mice, bearing xenograft, received 30 m. 131I-labelled intact monoclonal immunoglobulins (200mCi: 7,4MBq) and the imaging was performed on days 4, 8 and 12 after the application. After 4 days, a clear tumor accumulation of iodinated MUC 2-63 antibodies recognizing surface determinants was visible. This enrichment of monoclonal antibodies (MAbs) led to a characteristic tumor presentation on day 8. Obviously, the MUC 2-63 antibodies remain in the tumor tissue for a long time, so that even on day 12 satisfactory tumor imaging is possible. On the other hand, neither with normal mouse IgG nor with MUC 8-22 antibodies - which react with intracellular structures - could a tumor localization be achieved. The result of the studies on the distribution of 131I-MUC 2-63 on day 19 was that the activity in the tumor tissue was about 4.4 times higher than in the blood and even more times higher than in solid organs.