Figure 3.

Signals involved in the interaction between macrophages and erythrocytes regulating clearance.Macrophages exhibit some receptors for phosphatidylserine, such as Tim- 1, CD300, Stabilin-2, and Tim-4, which are presumed to deliver a pro-phagocytic signal (34–37). Band 3 is the major target of Nabs. Band 3 clustering and opsonization with Nabs and complements on the erythrocytes facilitates binding to the macrophage via Fc receptors and CR-1 and thereby promotes phagocytosis (38, 39). CD47 is a “don’t eat me” signal that plays a crucial role in erythrocytes homeostasis. Binding of CD47 to SIRPα generates an erythrocyte phagocytosis-associated deactivation of myosin IIA, which is a primary contributor to phagocytosis because of its participation in macrophage actinomyosin contraction. Tim, T cell immunoglobulin; Nabs, natural occurring antibodies; CR-1, complement receptor.