Estudio multicéntrico argentino de detección y seguimiento de clones de hemoglobinuria paroxística nocturna (HPN) por citometría de flujo multiparamétrica (CFM) de alta resolución

Paroxysmal nocturnal hemoglobinuria (PNH) is a non-malignant acquired clonal disease caused by a mutation in the PIGA gene of hematopoietic stem cells, which causes a total or partial absence of GPI anchored proteins in the cell membrane. New analytic strategies and new molecules allow an increased sensibility to detect of small PNH clones. Our aim was to study the incidence of PNH clones using MFC in different centres around the country and to highlight the advantages of standardized protocols using new molecules in the detection and diagnosis of PNH clones. To do this, 832 peripheral blood (PB) samples that had been scanned for PNH clones using flow cytometry (from 2013 until 2017) from 8 laboratories in different geographical areas of the country were analysed. PNH clones were identified and quantified in neutrophils and monocytes based on the partial or total expression absence of GPI anchored proteins such as CD14, CD66b, CD24, CD157, CD16 and FLAER, and in red blood cells (RBC) based on the absence of CD59. PNH clones were found in 189 (22.72%) of the 832 samples tested. Clinical suspicions were: PNH in 279 samples (33.53%), marrow aplasia in 73 (8.77%), cytopenia in 131 (15.75%), thrombosis of atypical location in 83 (9.98%), anemia in 170 (20,43%) and 96 without diagnosis (11.54%). The smallest clones (≤10%), detected in 8.65% of the samples (72/832), were found to have a larger incidence in patients with clinical suspicion of: bone marrow aplasia (36.11%), cytopenias (25.00%) and PNH (22.22%). Medium clones, >10-≤50, 3.85% of the samples (32/832), were found to have a larger incidence in samples with clinical suspicion of PNH. The clones >50, 10.22% of the samples (85/832), were found mostly in PNH. An increase in the number of positive results by detection of small clones was observed in patients with different cytopenias thanks to the new protocols, showing a higher sensibility and specificity. Regarding the management of the doctor-biochemist communication process, in the last 4 years a considerable improvement reporting patient information was observed. The percentage of patients without a diagnosis decreased drastically (from 41% in 2013 to 11.54% in 2017). This is of significant help in the interpretation of results and in gaining a better understanding of the disease.