Recombinant Anti-CD20 x Anti-CD28 Bispecific Antibody (Tandem Fab) is designed to be expressed as three chains derived from the variable domains of anti-CD20 and anti-CD28 parental antibodies. It contains a His-tag for affinity purification. And the two Fd regions are connected by a flexible linker. This BsAb can retarget T cells to tumor cells. It is designed for the research of Lymphoma therapy.