Analysis of epitopes of mouse monoclonal antibodies against human alpha-fetoprotein

Thirty-six monoclonal antibodies (MAbs) against human alpha-fetoprotein (AFP) were analyzed for the location of their epitopes by reacting them with a set of yeast recombinant AFP proteins using ELISA. Recombinant AFP proteins containing either one, two or all three domains, i.e. domain I, domain III, domain I-II, domain II-III and domain I-II-III, were produced and secreted into the culture medium of yeast cells harboring the expression plasmids. Epitopes of 13 MAbs were localized on domain I and 17 others were on domain III. However, the exact location of the epitopes of the remaining 6 MAbs could not be defined. The epitope of an antibody, namely AFY6, which was located in domain I, was successfully mapped on an octapeptide, C175KAENAVE182, using synthesized overlapping octapeptides.