Marlar Richard A, Gausman Jana N
Department of Pathology, University of New Mexico, Albuquerque, NM, 87131, USA.
Pathology and Laboratory Medicine Service, Oklahoma City VA Medical Center, Oklahoma City, OK, USA.
Methods Mol Biol. 2017;1646:153-160. doi: 10.1007/978-1-4939-7196-1_12.
Protein S (PS) is a Vitamin K-dependent protein that functions as a cofactor for the regulation of the coagulation system. PS works in conjunction with Activated Protein C to inactivate factors V and VIII. PS circulates in plasma either complexed to the complement protein, C4b Binding Protein or unbound. The unbound (or free) component is the functional form for the regulation of the coagulation system. PS can be measured in plasma by functional activity, the free (or unbound form) or both free and bound fractions (Total PS). The test most widely used for clinical evaluations is the Free PS Antigen assay (which is the surrogate of PS anticoagulant activity) and represents the protocol described in this chapter. The Free PS Antigen assay is an immunologic assay which specifically measures the unbound fraction of PS in test plasma. Other methods for assessing PS are also available, including PS activity and total PS Antigen assays, but protocols for these assays are not provided.
蛋白S（PS）是一种维生素K依赖蛋白，作为调节凝血系统的辅因子发挥作用。PS与活化蛋白C协同作用，使因子V和因子VIII失活。PS在血浆中循环，要么与补体蛋白C4b结合蛋白结合，要么处于未结合状态。未结合（或游离）成分是调节凝血系统的功能形式。可通过功能活性、游离（或未结合形式）或游离和结合部分（总PS）来测定血浆中的PS。临床评估中最广泛使用的检测方法是游离PS抗原检测（它是PS抗凝活性的替代指标），也是本章所述的方法。游离PS抗原检测是一种免疫检测方法，可特异性测量检测血浆中PS的未结合部分。评估PS的其他方法也有，包括PS活性检测和总PS抗原检测，但本章未提供这些检测方法的操作流程。
