Studies in Erythropoiesis: The Influence of the Glycocalyx of the Red Cell Membrane

摘要

The possible existence of a correlation between the removal from the circulation of aged cells and the production of new RBCs was investigated. An erythropoietic influence was found to be associated with the glycocalyx of the erythrocyte membrane. The influencing factor, presumably a desialated glycopeptide, asialoglycophorin, appeared to be masked on the young RBC by an amino ketosugar, sialic acid. Ostensibly during the aging process, an increasing amount of sialic acid becomes removed from the membrane to expose the underlying erythropoietic message. Sialic acid was removed enzymatically in vitro from the membranes of erythrocytes by incubation with neuraminidase from Clostridium Perfringens. Erythropoietic activity was assayed by measuring iron-59 uptake after injection or transfusion of test material into exhypoxic mice. The amount of erythropoietic activity was found to be directly related to the number of desialated erythrocytes transfused and to the degree of desialation of the transfused erythrocytes. Asialoglycophorin was shown to be an erythrocyte stimulating factor following its isolation from the membrane and subsequent injection into test mice. Both mouse and human asialoglycophorin were found to be stimulatory. (ERA citation 06:035493)