Objective To evaluate whether resonable and sensible cut off( CO) values were set up and used for treponema pallidum antibody( anti-TP) detection tests for donated blood samples in 11 blood agencies by enzyme-linked immunosorbent assay( ELISA).Methods 1 372 samples were processed for anti-TP using 1 or 2 of the 8 ELISA reagents in the11 blood laboratories. The samples with inconsistent results were re-confirmed by treponema pallidum pellet agglutination test( TPPA) to determine the true serological status o...