Molecular Pathology Laboratory Network

FLOW PNH

PNH Screen

Flow cytometry, multiparameter analysis

88184 – Flow cytometry, cell surface, cytoplasmic, or nuclear marker, technical component only, first marker
88185 x6 – Each additional marker (multiple)
88187 – Flow cytometry, interpretation, 2 to 8 markers

< 24 hours

Whole blood or bone marrow stable for 48 hours at room temperature

Specimens stored at incorrect temperature; Non-viable specimens; Specimens in inappropriate anticoagulant; Too few cells; Hemolysis; Specimen clotted

See report

Paroxysmal nocturnal hemoglobinuria (PNH) is a clonal hematopoietic stem cell disorder characterized by mutation of the X-linked phosphatidylinositol glycan (PIG-A) gene leading to a deficiency of the cell membrane anchor glycosylphosphatidylinositol (GPI) and a deficiency of GPI linked proteins and glycoproteins. Cells lacking these proteins have an increased susceptibility to lysis, and affected patients may present with intravascular hemolysis and hemoglobinuria, leukopenia or thrombocytopenia. At least 15 GPI dependent proteins have been shown to be lacking on the blood cells of patients with PNH. The absence of two of these proteins, CD59 and CD55, also known as membrane inhibitor of reactive lysis (MIRL) or protectin, and CD55, also known as decay-accelerating factor (DAF), are used as markers for PNH. CD59 and CD55 are evaluated on granulocytes, and CD59 is evaluated on erythrocytes using multiparameter flow cytometry. Patients with PNH have diminished to no expression of CD55 and CD59 on granulocytes and erythrocytes. Patients with PNH also have diminished FLAER reactivity on granulocytic cells.

CD59 and CD55 deficiencies are evaluated on either erythrocytes or granulocytes specifically gated in a multi-color flow cytometry procedure, using fluorochrome-labeled anti-human CD59 and CD55. Affected patients demonstrate either completely (PNH III) or partially (PNH I, PNH II) CD 59 and CD 55 deficient red cells and granulocytes.