Expression and characterization of a recombinant Fab fragment derived from an anti-human alpha-fetoprotein monoclonal antibody.

Alpha-fetoprotein (AFP) is a well-known molecular marker indicating the development of cancer as well as fetal abnormalities such as open neural tube defects. Accordingly the measurement of serum AFP is important for the diagnosis of hepatocellular carcinoma (HCC) and other abnormalities. Monoclonal antibodies (McAb) to AFP were produced to develop an immunoassay kit, and to study the possibility of an antibody (Ab) therapy. The immunoglobulin genes were cloned from hybridoma cells, and expressed in E. coli as an Fab soluble into a culture medium. The Fab of anti-AFP McAb exhibited binding to AFP and similar affinity compared to the original IgG. This recombinant antibody can be studied further for in vivo imaging and immunotherapeutics.