Unlike state-of-the-art receptor specific isolation procedures, the Streptamer® approach is fully reversible, i.e. staining or isolation reagents are completely removed by biotin (vitamin H) and the isolated cells not only preserve their full effector function but are predestined, from a regulatory perspective, for clinical use.
Streptamers comprise low affinity, Strep-tagged Fab fragments or MHC I molecules that are multimerized with Strep-Tactin® attached to a fluorochrome or a magnetic bead to generate multimers with high binding avidity.
Streptamers are either directed to antigen-specific CD8+ T-cell receptors (MHC I Streptamers) or any other cell surface receptors defining a cell subset including those of T-cells (CD3, CD4), regulatory T-cells (CD4, CD25, CD 45RA), natural killer cells (CD56) and stem cells (CD34, CD133) (Fab Streptamers).
Fab Streptamers are not only a novel extension of the MHC I Streptamers which are being used successfully for the antigenspecific staining and isolation of CD8+ T-lymphocytes but they open up totally new avenues for cell therapy.
All ligands (Fab- or MHC I-Streps) can either be attached to Strep-Tactin fluorochromes for cell staining or to Strep-Tactin magnetic beads for cell isolation.
Due to the complete reversibility (i.e. dissociation of staining and isolation reagents) cell samples can be repetitively stained with different Streptamer fluorochromes or sequentially be isolated with different Streptamer magnetic beads.
This modular Streptamer reagent system enables the economic generation of multiple receptor- or antigen-specific staining and isolation reagents.