Nilsson R, Davidsson B
Department of Immunology, Excorim KB, Sweden.
J Immunol Methods. 1990 Dec 31;135(1-2):77-80. doi: 10.1016/0022-1759(90)90258-w.
Quantitative determination of staphylococcal protein A in plasma is often hampered by the interaction between protein A and immunoglobulins. In human plasma, these interactions may not only involve the non-immune binding to the Fc or Fab regions of Ig but also antigen/antibody interaction by specific antibodies directed against protein A. In this paper we describe a method which can be used to quantitate nanogram amounts of protein A in the presence of human plasma. The ELISA used for the quantification of protein A is based on a double antibody solid-phase assay utilizing chicken anti-protein A as both capture and detector antibody. Protein A may be measured down to 5 ng/ml in plasma and 0.5 ng/ml in buffer. The plasma samples were heat-inactivated before analysis and this eliminated interference in the assay caused by interaction of protein A with an excess of immunoglobulins. This assay provides a reliable and convenient method for the detection and quantitation of soluble protein A in human plasma.
血浆中葡萄球菌蛋白A的定量测定常常因蛋白A与免疫球蛋白之间的相互作用而受到阻碍。在人血浆中，这些相互作用不仅可能涉及与免疫球蛋白Fc或Fab区域的非免疫结合，还可能涉及针对蛋白A的特异性抗体的抗原/抗体相互作用。在本文中，我们描述了一种可用于在人血浆存在的情况下定量纳克量蛋白A的方法。用于定量蛋白A的酶联免疫吸附测定（ELISA）基于一种双抗体固相测定法，该方法利用鸡抗蛋白A作为捕获抗体和检测抗体。血浆中蛋白A的检测下限可达5 ng/ml，缓冲液中为0.5 ng/ml。血浆样品在分析前进行热灭活，这消除了蛋白A与过量免疫球蛋白相互作用对测定造成的干扰。该测定法为检测和定量人血浆中的可溶性蛋白A提供了一种可靠且便捷的方法。
