Objective Humanizing murine anti TNF α antibody Fab fragment with the method of epitope guided selection. Methods Firstly, the Fd gene of a murine anti TNF α antibody was paired with a repertoire of human κ chain, and displayed on the filamentous phage forming a hybrid phage antibody library. After four round panning against TNF α, the hybrid antibody fragments containing human κ chain were obtained. The selected human κ chain genes were in turn paired with a repertoire of human Fd fragments formi...