RADIOIMMUNOIMAGING OF XENOGRAFT PANCREATIC-CANCER WITH I-131 MONOCLONAL-ANTIBODY P2

Monoclonal antibodies (McAbs) to pancreatic cancer were developed by f using SP2/0 cells and splenocytes from Balb/c mice immunized with CH-2 cells. The specific binding rates of McAb P1 and P2 were 40.1 and 43. 8%, respectively, shown by binding radioreactivity assay in vitro, whi ch were in sharp contrast with those of control groups (p < 0.05). The biodistribution of radioiodinated McAb P2 was studied by measuring pa rameters of tumor-specific radioreactivity in nude mice bearing CH-2 t umors. The ratios of tumors to nontumors were all >2 at 48 h. The loca lization index of cancer and the ratio of tumor to pancreas were 4.05 and 4.16, respectively, at 72 h. Therefore, I-131-McAbs may be useful for radioimmunoimaging (RII) of pancreatic cancer. After intraperitone al injection of I-131-McAb P2 into tumor-bearing nude mice, imaging of xenograft pancreatic cancer became increasingly distinct with the non specific background fading, especially in the period of 72-96 h. Exami nation of pancreatic cancer tissues by immunohistochemical methods rev ealed that McAb P2 was strongly positive (86%) in comparison with othe r tumors and normal tissues. The results demonstrated that clinical RI I of pancreatic cancer was feasible with McAb P2.