What is the role of fluorescent aerolysin in the diagnosis of paroxysmal nocturnal hemoglobinuria (PNH)?

Updated: May 20, 2021
  • Author: Emmanuel C Besa, MD; Chief Editor: Sara J Grethlein, MD, FACP  more...
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A more accurate alternative reagent for PNH screening and PNH clone measurement is the bacterial toxin aerolysin, which binds to RBCs via GPI anchor and initiates hemolysis. A modified, nonhemolytic form of a fluorescently labeled molecule has been developed that can detect PNH cells to a level of 0.5% (fluorescently labeled inactive toxin aerolysin [FLAER] binding of peripheral blood granulocytes). The advantage of this assay is that it can detect the clone in all hematopoietic cell lineages in one assay.

This is the most specific test for PNH, as FLAER binds the GPI anchor specifically. Thus, the lack of FLAER binding to granulocytes (measured by flow cytometry) is sufficient for the diagnosis of PNH. The disadvantage of the test is in measuring binding in the absence of adequate granulocytes, such as in severe aplastic anemia, when the number of circulating granulocytes is extremely low.

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