Fig. 2: Variability of RBC fate and lifespan.
From: A new role for erythropoietin in the homeostasis of red blood cells
a Dynamics of eat-me and don't-eat-me signals in two RBCs that differ in their initial expression of the latter according to Equation (15). b Outcomes of the interaction of RBCs in A with macrophages expressing different levels of don't-eat receptors. RBCs undergo the silent pathway if the difference between the number of “eat” and “don't-eat” signals perceived by the macrophage is above a critical threshold (silent threshold) and the immune pathway if the number of “don't” eat signals does not reach a minimum value (immune threshold). Macrophages with low or medium levels of don't-eat receptors (left and middle column, respectively) phagocytize both RBCs through the immune pathway. However, the timing of the phagocytosis is different, which translates into heterogeneous lifespans. If macrophages express more don't-eat receptors (right column) the lifespan of both RBCs is longer. In this case, the first one (top line) is now phagocytized through the silent pathway. Model parameters: α = 0.15, β = 0.25, E0 = 0.6, D0 = 4 and 2, rE = 10, and rD = 10, 20, and 40, δE = δD = 1. Parameters have been chosen arbitrarily to show the qualitative behavior of Equations (15) and (16). To simplify the graphs, axes units are not shown.
