Identification of an amino acid responsible for the CD3 polymorphism in cynomolgus monkeys (Macaca fascicularis)

Abstract: The FN18 monoclonal antibody (mAb), directed to CD3 molecules, did not react with the lymphocytes of some cynomolgus monkeys ( Macaca fascicularis ), because of the polymorphism of the CD3ɛ chain. The epitope recognized by the FN18 mAb was successfully expressed on COS7 cells upon transfection of plasmid DNA coding for the CD3ɛ derived from T cells of a FN18 positive cynomolgus monkey. By construction and expression of plasmid DNA encoding the mutant CD3ɛ, the amino acid residue at position 67 was demonstrated to be involved in the formation of an epitope recognizable by the FN18 mAb.