Page 110 - 2020_02-Haematologica-web

R. Huisjes et al.
and lower deformability as they “aged”, spending more time in the circulation getting more “senescent” than the highly unstable cells of patients with severe HS. Thus, RBC lifespan and decrease in Elmax appeared to be reliable markers of disease severity (Figure 4B), regardless of the genotype.
Delayed clearance of RBC in patients with mild HS allows a more gradual loss of the cell membrane (Figure 4G, Online Supplementary Figure S3), which results in bet-
ter conservation of RBC deformability (Figure 4B) and the ability to form dense cells (Figure 4C-E, Online Supplementary Figure S2). Direct measurements of mem- brane shedding by monitoring plasma-borne vesicles is challenging due to their fast sequestration and clear- ance.32–34 However, higher levels of circulating RBC vesi- cles were detected in plasma from patients with moder- ate/severe HS (Figure 4G). This finding is in line with an increase in other markers of membrane loss, such as
ABC
DEF
GHI
J
Figure 4. Red blood cell density and stability as markers of severity in hereditary spherocytosis. Patients with hereditary spherocytosis (HS) are grouped according to clinical severity (i.e. mild, moderate/severe and splenectomized) (reference range in gray area). (A) Glycated hemoglobin (HbA1c) (mmol/mol), (B) maxi- mum deformability (EImax), (C) hypertonic osmolarity at 50% of maximal elongation (Ohyper) (mOsmol/L), (D) mean corpuscular hemoglobin concentration (MCHC) (g/L), (E) Position of M-fraction (%), (F) mean cell pro- jected area (MPA) (in arbitrary units, a.u.), (G) red blood cell (RBC) vesicles (particles/1012 RBC/L plasma), (H) eosin-5′-maleimide (EMA)-binding (%), (I) RBC distribution width (RDW) (percent coefficient of variation, %CV), (J) mean cell projected area distribution width (MPA DW). Significant differences are represented by horizontal bars, and significance levels are noted: *P≤0.05, †P≤0.01 or ‡P≤0.001.
344
haematologica | 2020; 105(2)