Aleksandra M. Glodek, Rossen Mirchev, David E. Golan,Joseph A. Khoory, Jennie M. Burns, Sergey S. Shevkoplyas, Anne Nicholson-Weller and Ionita C. Ghiran
Microbes as well as immune complexes and other continuouslygenerated inflammatory particles are efficiently removed from the human circulation by red blood cells (RBCs) through a process called immune-adherence clearance. During this process, RBCs use complement receptor 1 (CR1, CD35) to bind circulating complement-opsonized particles and transfer them to resident macrophages in the liver and spleen for removal. We here show that ligation of RBC CR1 by antibody and complement-opsonized particles induces a transient Ca++ influx that is proportional to the RBC CR1 levels and is inhibited by T1E3 pAb, a specific inhibitor of TRPC1 channels. The CR1-elicited RBC Ca++ influx is accompanied by an increase in RBC membrane deformability that positively correlates with the number of pre-existing CR1 molecules on RBC membranes. Biochemically, ligation of RBC CR1 causes a significant increase in phosphorylation levels of β-spectrin that is inhibited by pre-incubation of RBCs with DMAT, a specific casein kinase II inhibitor. We hypothesize that the CR1-dependent increase in membrane deformability could be relevant for facilitating the transfer of CR1-bound particles from the RBCs to the hepatic and splenic phagocytes.
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