New Approaches for the Detection and Characterization of Alpha-Fetoprotein Epitope Variants

Abstract

Alpha-fetoprotein (AFP) is an embryo-specific protein of mammalian sera that consists of a single glycosylated polypeptide chain (∼70 kD) with 5–6 epitope clusters located on the native molecule. We have elaborated three approaches for the separation of AFP into fractions (variants) that are different in the distinct epitope expression on the native molecule. For this, we have used three technologies largely based on immunoaffinity electrochromatography and electrophoresis/immunoblotting. The separation of these variants was facilitated using monoclonal antibodies previously characterized to the 5 epitope clusters and two individual epitopes on AFP in the ISOBM international workshop. We have shown that these approaches facilitate the identification of cryptic epitopes in AFP, and the relevance of these findings is discussed.

Tumor Marker Workshops

“…The TD-2 Workshop went further in defining the relationship between the epitope groups reaching a consensus of 5 major domains. As with many glycoprotein tumor markers, glycosylation variants continue to affect the measurement [10,11], and influence the diagnostic capacity of AFP. Further developments in this area may represent a possible subject for future AFP Workshops.…”