Receptor-specific isolation of lymphocytes with reversible Fab Streptamers

Magnetic Fab Streptamers, adducts of Strep-tagged Fab fragments (Fab-Streps) and Strep-Tactin® magnetic beads, are directed against cell surface markers including those of T cells (CD3, CD4, CD8), memory T cells (CD8, CD62L, CD45RA-) and regulatory T cells (CD4, CD25, CD45RA).

We offer two sizes of magnetic beads

magnetic microbeads to be used with a permanent magnet (e.g. StrepMan or Dynal magnet) for manual cell isolation
magnetic nanobeads to be used with magnetic columns (e.g. from Miltenyi) for manual and automated cell isolation.

a) Cell Isolation with Magnetic Microbeads (for permanent magnets)

1) Fab-Streps (Strep-tagged Fab fragments) are multimerized with Strep-Tactin® attached to a magnetic bead to generate multimers with high binding avidity (Fig.1).

Fig.1: Fab Streptamer® Magnetic Microbead

2) Selection of the target cells is performed with our StrepMan permanent magnet. We recommend a horizontal position for separation of the magnetically labeled cells (top). For removal of the magnetic Streptamers from the isolated cells with biotin we recommend an upright position of the StrepMan magnet (bottom). Cells are left phenotypically and functionally indistinguishable from untreated cells.

Reversible manual cell isolation with Streptamer Magnetic Microbeads

StrepMan magnet for Streptamer® Cell Isolation with Magnetic Microbeads

Fig.2: StrepMan magnet for Streptamer® cell isolation with Strep-Tactin® magnetic microbeads

b) Cell Isolation with Magnetic Nanobeads (for magnetic columns)

1) Fab-Streps (Strep-tagged Fab fragments) are multimerized with Strep-Tactin® attached to a magnetic bead to generate multimers with high binding avidity (Fig.1).

Fig.1: Fab Streptamer® Magnetic Nanobead.

2) After separation of the target cells on a magnet column, the isolation reagents can be completely removed from the cells with biotin (Fig.2). Cells are left phenotypically and functionally indistinguishable from untreated cells.

Cell isolation using Streptamer magnetic nanobeads

Fig.2: Streptamer® Magnetic Nanobeads are recommended when selection of cells is performed with an automated selection machine from Miltenyi (autoMACS®, CliniMACS®). Cells are mixed with Streptamer® Magnetic Nanobeads and loaded onto a magnet column (Miltenyi). Cells bound to magnetic beads are retarded on the column through a high gradient magnetic field. After elution of the target cells multimerization is reversed by the addition of biotin and the low affinity Fab-Strep molecules dissociate completely from the cell surface.