Preparation and characterization of monoclonal antibodies specific to placenta ferritin.

Ferritins are a group of isomeric proteins which function as the major iron-storage protein of mammalian tissues. Some of the isoferritins have low isoelectric points, and are found in placenta and in malignant tissues and have therefore been termed carcinofetal ferritins. With the use of hybridoma technology, monoclonal antibodies (McAbs) specific to human placenta ferritin(s) were produced in order to characterize the heterogeneity of the molecule and to answer the question whether a specific antigenic determinant is associated with placenta and/or carcinofetal ferritin(s). Two McAbs designated H-9 and G-8 were developed. McAb H-9 bound specifically and exclusively to the ferritin isolated from human placenta, whereas G-8 McAb bound to placenta ferritin and cross-reacted with ferritins isolated from human spleen and liver. No cross-reaction was observed between H-9 and G-8 reactive determinants. It was found further that the two antigenic determinants - the one recognized by G-8 and that recognized by H-9 McAbs - are molecularly associated on placenta ferritin. The results of this study led us to term the G-8 a 'common' ferritin antigenic determinant and H-9 a 'private' embryonic ferritin determinant.