CELL DISPLAY LIBRARY FOR GENE CLONING OF VARIABLE REGIONS OF HUMAN-ANTIBODIES TO HEPATITIS-B SURFACE-ANTIGEN

A novel cell display system was developed for cloning the variable reg ion (V) genes of antigen-specific human antibodies. The system is base d on an antibody library displayed on the surface of COS cells, using a plasmid vector designed to direct expression of membrane-bound antib odies. COS cells expressing antigen-specific antibodies were separated using a flow cytometer for their binding to a fluorescent dye-labeled antigen. To test the performance of this system, we cloned V genes of 4 antibodies directed against hepatitis B surface antigen (HBsAg) fro m a library prepared from peripheral blood lymphocytes of a vaccinated donor. These membrane-bound anti-HBsAg antibodies were easily convert ed to soluble forms, all of which showed a size similar to human serum IgG in SDS-PAGE and the same specific binding to HBsAg as membrane-bo und forms in ELISA. All V-H and V-kappa gene segments of the 4 clones isolated in this study belonged to VHIII and VkappaI subgroups, respec tively. These findings demonstrate the potential and selection capabil ities of our cell display system for cloning the V genes of antigen-sp ecific human antibodies.