Hemoglobin Binding to the Red Blood Cell (RBC) Membrane Is Associated with Decreased Cell Deformability

Abstract

The deformability of red blood cells (RBCs), expressing their ability to change their shape as a function of flow-induced shear stress, allows them to optimize oxygen delivery to the tissues and minimize their resistance to flow, especially in microcirculation. During physiological aging and blood storage, or under external stimulations, RBCs undergo metabolic and structural alterations, one of which is hemoglobin (Hb) redistribution between the cytosol and the membrane. Consequently, part of the Hb may attach to the cell membrane, and although this process is reversible, the increase in membrane-bound Hb (MBHb) can affect the cell's mechanical properties and deformability in particular. In the present study, we examined the correlation between the MBHb levels, determined by mass spectroscopy, and the cell deformability, determined by image analysis. Six hemoglobin subunits were found attached to the RBC membranes. The cell deformability was negatively correlated with the level of four subunits, with a highly significant inter-correlation between them. These data suggest that the decrease in RBC deformability results from Hb redistribution between the cytosol and the cell membrane and the respective Hb interaction with the cell membrane.

Keywords: RBC deformability; hemoglobin; membrane-bound hemoglobin; red blood cells.

Figure 1

Variability in the content of membrane-bound Hb-subunits (expressed by (Ln (LFQ)). Statistical analysis was carried out for 15 samples of healthy adult RBCs.

Figure 2

Correlation between the level of the RBC membrane-bound β, α, and δ subunits (Ln (LFQ)) and the cell deformability (AER); for statistical analysis, see Table 4.

Figure 3

Scheme of cell-flow analyzer CFA.

Figure 4

A. Image of RBC field in the CFA flow-chamber under flow-induced shear stress of 3.0 Pa. B. Highly deformable cell (ER = 2.3). C. Non-deformable cell (ER = 1).