Eady R P, Chapple J C, Hough D W, Stevenson G T
J Immunol Methods. 1975 Jun;7(2-3):179-86. doi: 10.1016/0022-1759(75)90015-0.
The specificity of a solid phase radioimmunoassay for immunoglobulin antigens, human Fab-mu in the case illustrated, has been assessed. The anti-Fab-mu serum available reacted well on gel diffusion with all Fab-mu- and light chain-containing proteins. In contrast the radioimmunoassay, in which unlabelled test antigen competes with radiolabelled Fab-mu for anti-Fab-mu coupled to Sephadex beads, was sensitive only to proteins containing entire Fab-mu regions. A double antibody radioimmunoassay showed comparable or greater sensitivity for Fab-mu-containing proteins, but was much less specific. By using Fab-gamma as the labeled antigen, with only light chain determinants reacting with the anti-Fab-mu, the solid phase assay was rendered polyspecific in being sensitive to all proteins containing light chain. Reasons for the specificity of the solid phase assay are discussed: steric factors can be expected in some cases to permit strong binding of antigen by multiple bonds, in others to restrict the number of molecular determinants simultaneously available to antibody.
已对一种用于免疫球蛋白抗原（在所示案例中为人类Fab - μ）的固相放射免疫测定法的特异性进行了评估。现有的抗Fab - μ血清在凝胶扩散试验中能与所有含Fab - μ和轻链的蛋白质良好反应。相比之下，在放射免疫测定法中，未标记的测试抗原与放射性标记的Fab - μ竞争结合到交联葡聚糖珠上的抗Fab - μ，该方法仅对含完整Fab - μ区域的蛋白质敏感。一种双抗体放射免疫测定法对含Fab - μ的蛋白质显示出相当或更高的敏感性，但特异性要低得多。通过使用Fab - γ作为标记抗原，只有轻链决定簇与抗Fab - μ反应，固相测定法变得具有多特异性，即对所有含轻链的蛋白质敏感。文中讨论了固相测定法具有特异性的原因：在某些情况下，空间因素可预期允许抗原通过多个键进行强结合，而在其他情况下，则会限制抗体同时可利用的分子决定簇的数量。
