Flow Cytometry Reporting

In flow cytometry, normal cells provide intrinsic controls against which antigen expression and staining intensity is measured. The 2006 Bethesda Consensus outlined standardized criteria by which staining intensity should be reported.

Antibody expression / distribution

  • Positive: antigens expressed (relative to a negative control)
  • Negative: antigens not expressed
  • Partial: antigens expressed in a subset of the population in question
Flow Cytometry: Antigen Expression
Flow cytometry analysis from a patient with chronic lymphocytic leukaemia, showing the staining intensity of the abnormal cells, normal T cells and normal B cells. The abnormal cells are positive for CD19 because there is antigen expression relative to a negative control (normal T cells in red).

Staining Intensity

  • Dim: positive with a lower intensity than a positive population
  • Bright: positive with a higher intensity than a positive population
  • Heterogenous: variable expression or a spectrum of intensity (as opposed to a tight, uniform cluster of events)
Flow Cytometry: Staining Intensity
Flow cytometry analysis from a patient with chronic lymphocytic leukaemia, showing the staining intensity of the abnormal cells, normal T cells and normal B cells. The abnormal cells are dim for CD19 because their staining intensity is less than that of the normal B cells.
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