PROBLEM TO BE SOLVED : To provide compositions and methods for improving the safety of blood-brain barrier receptor-mediated blood-brain barrier transport in treating a neurological disorder and the like. SOLUTION : A method of transporting a compound across the blood-brain barrier comprises exposing the blood-brain barrier to an antibody which binds with low affinity to a blood-brain barrier receptor coupled to the compound, so that the antibody transports the compound coupled to the antibody across the blood-brain barrier, where reduction of red blood cell levels upon antibody administration is decreased or eliminated. SELECTED DRAWING : None COPYRIGHT : (C)2019, JPO&INPIT