Gene expression of erythrocyte receptor: Regulation of erythrocyte-receptor synthesis in T-lymphocytes

Human T-lymphocytes bind sheep erythrocytes (SRBC) under stringent in vitro conditions to form rosette-shaped figures when viewed under a microscope [l-5]. Although the phenomenon has no known in vivo consequences it has been an extremely useful marker of human T-cells and an indicator of maturation. The binding appears to be the consequence of the presence of specific glycoproteins on the lymphocyte surface which have a selective affinity for a fetuinlike ~ycopept~de on the sheep erythrocyte membr~e [6-91. Peptide hormones synthesized by thymic epithelial cells have been shown to induce its biosynthesis [ 10,111, but very little is known regarding the molecular events underly~g the induction process or the regulation of the biosynthetic process once it is initiated. These experiments are the first in a series designed to elucidate the regulatory mechanism of thymic hormones on expression of erythrocyte receptor. Using the experimental model in 1121 we demonstrate that the biosynthesis of the erythrocyte binding protein is under a transc~ptional ~ontrol”me~hanism and once the genome of this protein is turned on during the maturation process, it continues to express without any further hormonal requirement.