I performed a positive selection and the purity of my target cells is low. What could be the reason for this?

Check the following factors:

  • Did you incubate at temperatures higher than 4°C or longer than indicated on the data sheet?
  • Did you use more antibody or MACS MicroBeads than indicated on the data sheet?
  • Did you choose the right column? Was the column overloaded?
  • Were there clumps in your cell suspension? Filter your cells before staining with MACS MicroBeads to avoid clumps.
  • Were there a lot of dead cells in your sample? Dead cells bind unspecifically to antibodies and are therefore co-enriched to a certain extent. Check your sample preparation and try to avoid large numbers of dead cells.
  • What is the primary source of the material? Frozen materials usually contain more dead cells. Dead cells are usually gated out during flow cytometric analysis.