Radioimmunodetection of human hepatocellular carcinoma graft in a nude mouse with a monoclonal antibody

We have produced 5 murine monoclonal antibodies (MAbs) (H-12-1, L-7-6, H-14-2, L-8-1 and H-21-1) to surface antigens on human hepatocellular carcinoma (HCC) cell lines and characterized their reactivities to various cultured cell lines and fresh human tissues by indirect immunofluorescence and immunohistological study. Among them, the MAb L-8-1 reacted with 2 of 3 HCC cell lines and 5 of 6 fresh HCC tissues. The L-8-1 did not react with any components of fresh normal liver tissue. The L-8-1 antigen was a non-secretary membrane protein with a molecular size of 18 KDa. Radioscintigraphy revealed, without the subtraction of the blood pool image, the preferential localization of the isotope at the human HCC xenografts in nude mice to which radiolabeled L-8-1 was administered. Our data supports the selective accumulation of ¹³¹I^-labeled L-8-1 in the HCC compared with ¹²⁵I-labeled control IgG. This monoclonal antibody L-8-1 may be potentially useful for radioimmunodetection and immunoconjugate therapy.