Cellular site for prothrombin synthesis

¹ Department of Physiology and Pharmacology, Wayne State University College of Medicine, Detroit, Michigan

The cell type responsible for synthesis of any of the trace plasma proteins concerned in blood coagulation has not been identified before. In this study the fluorescent antibody technique was used to find out the cellular site for prothrombin synthesis. Fluorescent antiprothrombin precipitated out on bovine liver parenchymal cells containing adequate concentrations of prothrombin. The specificity of the reaction was established using various absorptive and blocking techniques. The antiprothrombins produced were species specific. Not all parenchymal cells reacted uniformly with fluorescent antiprothrombin so that groups of brilliantly fluorescing cells were seen among cells displaying dim natural fluorescence. This may mean that only a certain type of parenchymal cell produces prothrombin or that there is cyclic production of prothrombin.