Epitope Analysis and Primary Structures of Variable Regions of Anti-human FcεRI Monoclonal Antibodies, and Expression of the Chimeric Antibodies Fused with Human Constant Regions

Abstract

The structural analysis of monoclonal antibodies (mAbs) against the α subunit of the high affinity IgE receptor (FcεRIα) is an alternative approach to obtaining information for the design of inhibitors that will block complementary interaction between IgE and FcεRIα and to analyzing the various biological effects induced by anti-FcεRIα autoantibodies in chronic urticaria. In this study, epitopes for mouse anti-human FcεRIα mAbs and primary structures of variable regions of the mAbs were analyzed. Three mAbs inhibitory for IgE-binding reacted to the deletion mutants of FcεRIα containing the whole second immunoglobulin-like domain as well as IgE did. On the other hand, two uninhibitory mAbs reacted to those containing the whole first immunoglobulin-like domain. The cDNAs for variable regions of the five mAbs were cloned and sequenced. Two inhibitory mouse/human chimeric antibodies were expressed in COS7 cells and bound to Chinese hamster ovary transfectant cells expressing FcεΡι (CHO/αβγ), and these inhibited the binding of IgE to CHO/αβγ cells.

• high-affinity IgE receptor
• monoclonal antibody
• epitope
• variable region
• chimeric antibody