Strep-Tactin® Magnetic Microbeads

Strep-Tactin® Magnetic Microbeads are microspheres covalently linked to Strep-Tactin®. They are suitable for labeling antigen-specific cytotoxic T cells (MHC I Streptamer®) or surface marker-specific cells (Fab-TACS®/Nano-TACS®). To target specific cells, MHC I complexes, low affinity Fab fragments or nanobodies fused to a Twin-Strep-tag® (MHC I-Streps, Fab-Streps or Nano-Streps) are required in addition to fluorescent Strep-Tactin®. Strep-Tactin® multimerizes MHC I-Streps or Fab-/Nano-Streps, ensuring stable binding to cells. The resulting magnetic complexes can be used to label cells that are specific for the respective peptide-loaded MHC I molecule or for a selected surface marker. The addition of biotin reverses the multimerization and causes the dissociation of MHC I-Streps or Fab-/Nano-Streps from the cell surface. The complete removal of all labeling reagents permits serial positive selection as well as depletion steps and reserves the cells’ full biological activity.