An anti-CD20 double antibody / receptor and a method of use of a human transfer agent are provided. Claim 1: a double antibody consisting of (a) two antibodies, each consisting of a short chain antibody and a long chain antibody, At these junction points, each couple in the long chain and the short chain is specifically connected to the first antigen, (b) additional magic fragment, which merges with any C-terminal of the long chain antibody,At the additional Fab polymerization point, each scFv is specifically bound to the second antigen, and each scFv contains the rest of the amino acid arginina (not other wild glutamate) at the position 123 of the scFv constant (LC)； E123r mutation, at position 124, the rest of the amino acid lysine (rather than other wild glutamate； q124k mutation) (according to Kabat number)In the first constant long chain (ch1), each long chain antibody contains residual glutamic acid (not other wild lysine； mutagenic k147e), and there is residual glutamic acid (not other wild amino acids) at 147th position； Mutacion k213e (according to Kabat EU index number)In addition to the magic fragment, especially the second antigen, there is a cross field, Therefore, short chain constant domain (CL) and long chain constant domain (ch1) are substituted for each other. The first antigen is human CD20, and the second antigen is the recipient of human metastasis.Se proporcionan anticuerpos biespecíficos anti-CD20 humano / receptor de transferrina humano y métodos para el uso de los mismos. Reivindicación 1: Un anticuerpo biespecífico formado por: a) un anticuerpo que contiene dos parejas, cada una de una cadena corta de anticuerpo y una cadena larga de anticuerpo, en el que los sitios de unión formados por cada una de las parejas de la cadena larga y la cadena corta se unen específicamente al primer antígeno y b) un fragmento Fab adicional, dicho fragmento Fab adicional está fusionado con cualquier extremo C de una cadena larga del anticuerpo, en el que el
