Most prevalent hypotheses for red cell clearance mechanism(s) are expression of neoantigens on red cell surface, exposure phosphatidylserine and decreased deformability. Several of these changes have been proposed as a recognition tag for macrophages. Red cells undergo several physicochemical changes as they age in the circulation. Despite large number of investigations, the precise molecular mechanism by which macrophages recognize senescent red blood cells for clearance remains elusive.
This is an extremely efficient process as macrophages phagocytose about 5 million erythrocytes every second without any significant release of hemoglobin in the circulation. Normal human red blood cells have an average life span of about 120 days in the circulation after which they are engulfed by macrophages. 4Huntsman Cancer Institute, University of Utah, Salt Lake City, UT, United States.3University of Utah School of Medicine, Salt Lake City, UT, United States.
DeBakey Veterans Affairs Medical Center, Houston, TX, United States
