Monoclonal antibodies with fine specificities distinguishing alpha-fetoproteins of hepatoma and yolk sac tumor origin.

Monoclonal antibodies with fine specificities distinguishing alpha-fetoproteins of hepatoma (HEP-AFP) and yolk sac tumor (YST-AFP) origin have been obtained. These murine antibodies were produced by hybridomas made by fusion of X63-Ag8.653 myeloma cells with BALB/c spleen cells immunized with either HEP-AFP or YST-AFP and selected for their differential association with these antigens on the basis of Scatchard plot analysis. Three monoclonals (MA120, MA132 and MA136) selectively reacted with HEP-AFP. Their reactivity with YST-AFP was low. One monoclonal (MA122) reacted strongly with YST-AFP, whereas the reaction with HEP-AFP was significantly less strong. The difference in the association constants of these antibodies for the two AFPs appeared to be due to their specificity for the carbohydrate portions of the AFPs, which are different, at least in part. Indirect immunoperoxidase staining confirmed that MA122 was able to stain sections of an infantile embryonal carcinoma, but not of hepatoma.