In paroxysmal nocturnal hemoglobinuria (PNH) different clones of cells may show different amounts of surface proteins that are anchored to glycosyl phosphatidylinositol (GPI).


If the red blood cells are stained with labeled anti-CD59 or other red blood cell marker and examined in a flow cytometer, then the intensity of fluorescent signal is proportionate to the density of the surface protein.


There are 3 potential types of deficiency in the surface proteins. A patient may show from 1, 2 or all 3 of the different types depending on the clonal mix.


Intensity of Fluorescence

Deficiency in Surface Proteins



none (normal)

Type I



Type II

none to low


Type III


If the concentration of Type III cells is high, then the risk of hemolysis is high.


A high concentration of Type I or Type II cells is associated with a low rate of hemolysis.



• A patient with PNH may have normal RBC phenotype but abnormal clones in the granulocyte and/or monocyte series.


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