Recombinant Anti-CD22 x Anti-saporin Bispecific Antibody (Tandem Fab) is designed to be expressed as three chains derived from the variable domains of anti-CD22 and anti-saporin parental antibodies. It contains a His-tag for affinity purification. And the two Fd regions are connected by a flexible linker. This BsAb can be used in pretargeting system and deliver immunotoxin to tumor cells. It is designed for the research of Lymphoma therapy.