Paroxysmal nocturnal hemoglobinuria (PNH) is a rare form of acquired hematopoietic stem cell disorder leading to a partial or complete loss of all glycophosphatidyl-inositol (GPI)-linked proteins. The clinical spectrum of the disease varies from hemolytic anemia, bone marrow failure, thrombosis in unusual sites to an increased incidence of acute myeloid leukemia. Diagnostic flow cytometry offers a rapid means to provide a definite identification for cases of unexplained hemolytic anemias and bone marrow abnormalities.
Flow Cytometry (BD FACS Canto II)
We adopted a multi-parameter approach incorporating FLAER 2, a mutated form of a bacterial toxin that specifically binds to the GPI moiety of GPI-linked structures. FLAER is more sensitive than CD59 in detecting small abnormal granulocyte populations and is used in conjunction with antibodies to other GPI-linked antigens on granulocytes (CD24 for neutrophils or CD14 for monocytes). PNH clones on erythrocytes are detected using CD59. Demonstration of deficiency or loss of two GPI-s (one in the case of erythrocytes) on two cell lineages (erythrocytes, granulocytes and monocytes) is required for the diagnosis of PNH.