The present invention provides, inter alia, a method for cell-specific modulation of a target antigen. The method comprises contacting a target cell having the target antigen on the surface of the target cell with: (a) first multi-specific antigen-binding polypeptide comprising: (i) a cell-specific antigen binding domain (C1), (ii) a target antigen binding domain (T1)； and (b) a second multi-specific antigen-binding polypeptide comprising: (i) a cell-specific antigen binding domain (C2), (ii) a target antigen binding domain (T2)； wherein C1 and C2 interact with the same cell-specific antigen, and the cell-specific antigen and the target antigen are on the same target cell. Pharmaceutical compositions and kits thereof are also included in the present invention.
