Shortened lifespan of paroxysmal nocturnal haemoglobinuria‐affected RBC estimated from differences in ratios of CD59‐negative populations between reticulocytes and whole RBC

Abstract

Paroxysmal nocturnal haemoglobinuria (PNH) is a haemolytic disease characterized by complement-sensitive red blood cells (RBC). PNH-affected RBC (PNH-RBC) should have a shortened mean lifespan (MLS); however, direct measurement is difficult. We have recently developed a sensitive flow cytometric assay to analyse PNH-affected reticulocytes that may closely correspond to the PNH clone-derived erythropoiesis. Naturally, the CD59-negative populations in reticulocytes were larger than those in whole RBC in PNH. We estimated the MLS of PNH-RBC in six PNH patients from the differences in the ratios of CD59-negative populations between reticulocytes and whole RBC. The MLS of PNH-RBC was calculated using the following formula: W/100 = R x M/[(100 - R) x 120 + R x M], where W, percentage CD59-negative whole RBC; R, percentage CD59-negative reticulocytes; M, MLS (days) of CD59-negative RBC. The MLS of PNH-RBC, estimated as 16-45 days in the PNH patients, showed a weak positive and a weak negative relation with RBCs and percentage reticulocytes, respectively, among the patients. The MLS, in individual patients, altered irrespective of RBC and percentage reticulocytes. The MLS calculated from our methods may be a parameter that evaluates the haemolytic conditions in PNH.

Enhanced expression of CD71, transferrin receptor, on immature reticulocytes in patients with paroxysmal nocturnal hemoglobinuria

“…In a previous study, we showed that the ratios of PNH‐affected reticulocytes closely corresponded to PNH clone‐derived erythropoiesis; based on such assumptions, we proposed a formula to calculate the mean life span of PNH‐RBC from differences in the ratios of CD59‐negative populations between reticulocytes and whole RBC (Ninomiya et al. , 2008).…”