Please print, complete and submit the Advance Beneficiary Notice (ABN) along with the Flow Cytometry Requisition before shipping the specimen. Ham's acid hemolysin and sucrose lysis tests have been replaced by flow cytometric testing for glycosylphosphatidyl inositol (GPI)-anchored proteins CD55 and CD59, and aerolysin binding. These proteins are not expressed on PNH blood cells and their lack of expression is determined by flow cytometric assay. The channel-forming toxin, aerolysin, and its inactive precursors, proaerolysin, bind selectively with a high affinity to the GPI anchor itself. The lack of CPI anchor on blood cell surface will decrease the ability of fluorescently labeled protein aerolysin (FLAER) to bind to nucleated blood cells in patients with PNH. Paroxysmal nocturnal hemoglobinuria (PNH) is a stem cell disorder in which the affected cells are deficient in GPI-anchored proteins. GPI-anchored proteins include a number of important molecules on the surfaces of blood cells of all lineages. These include CD55 (decay-accelerating factor, DAF) and CD59 (membrane inhibitor of reactive lysis, MIRL) which protect against accidental activation of the complement system and cell lysis. Determination of CD55 and CD59 must be performed on fresh whole blood. Both monocytes and granulocytes are analyzed for CD55/CD59 expression and aerolysin bindings. Granulocytes are the most sensitive population in which to detect GPI-anchored protein deficiency. Two additional markers are performed for gating purposes, CD45 (leukocyte common antigen) and CD33 (myeloid antigen). Results are issued as a Bone Marrow (H-6) report interpreted by a pathologist. The number of GPI-anchored protein deficient cells can vary widely from case to case. Those patients with the highest relative numbers of GPI-anchored protein deficient cells are most likely to have classical PNH symptoms, while those with small relative numbers are more likely to present with aplastic anemia or myelodysplastic syndrome. About 20-25% of patients with aplastic anemia and MDS have been found to demonstrate small clones of PNH cells, so studies for PNH may also be indicted in patients with these diagnoses. REFS: 1)Richards, S et al. Application of Flow Cytometry to the Diagnosis of Paroxysmal Noctural Hemoglobinuria. Cytometry 2000; 42:223-233. 2)Dunn, D, et al. Paroxysmal Nocturnal Hemoglobinuria in Patients with Bone Marrow Failure Syndromes. Ann Int Med 1999; 131:401-408. 3) Brodsky RA, et al. Improved detection and characterization of paroxysmal nocturnal hemoglobinuria using fluorescent aerolysin. Am J Clin Pathol 2000; 114:459-66.

Technical: 88184 x1 and 88185 x3 Professional: 88187 - 26