Flow cytometric measurement of glycosylphosphatidyl-inositol-linked surface proteins on blood cells of patients with paroxysmal nocturnal hemoglobinuria

Abstract

Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired disorder of hematopoiesis in which affected cells are deficient in glycosylphosphatidyl- inositol (GPI) anchored surface proteins. The authors used flow cytometry to study 10 patients with PNH. They used a comprehensive panel of monoclonal antibodies against all nine currently known GPI-linked surface proteins (CD14, CD16, CD24, CD48, CD55, CD58, CD59, CD67, CD73) on cells of various lineages. Deficient cells were identified in the granulocytic-monocytic and erythroid lineages in all patients. However, the lymphoid lineage was affected in only eight patients. The patterns of deficiency were variable, with deficient cells constituting a part to all of the cells in the lineages tested. Certain proteins, including CD16, CD58, and CD59, appeared to be preferentially expressed, despite severe deficiencies of other GPI-linked proteins. Moreover, a trimodal pattern of expression of CD16, CD48, and CD59 was observed, in which a population of cells with intermediate levels of expression were identified in addition to positive and deficient cells. The authors' findings indicated a great degree of heterogeneity in the patterns and levels of expression of the GPI-linked proteins in the various cell types, as well as a possible heterogeneity in lineage involvement. The different patterns of expression of GPI-linked proteins should be considered when using flow cytometry to diagnose PNH. Finally, the clinical progression in some of the patients suggested a possible link between PNH, aplastic anemia, and myelodysplasia.