Hess P P, Mastropaolo W, Thompson G D, Levinson S S
Department of Pathology, University of Louisville, KY.
Clin Chem. 1993 Aug;39(8):1734-8.
We present a case in which kappa free light chains caused difficulty in interpreting classical urinary immunoelectrophoresis, but immunofixation electrophoresis (IFE) demonstrated the presence of a lambda-Bence Jones protein. Analysis of the urine by Ouchterlony double diffusion and IFE after gel-filtration chromatography showed that the difficulty was caused by the presence of large amounts of polyclonal free light chains. The workup also demonstrated that although IFE is the more sensitive and specific technique, IFE performed on concentrated urinary samples is especially subject to misinterpretation unless densely staining patterns are diluted and reassayed. This process of sample dilution provides a means for titrating antigen and antibody concentrations such that condition-specific patterns become visible on the gel. This workup also shows that, at some dilutions, polyclonal free light chains may migrate in the same manner as an oligoclonal band in a so-called ladder configuration. These bands were observed from both monomeric and dimeric fractions isolated by gel chromatography, consistent with reports that this pattern is largely linked to the isoelectric points of the molecules. We speculate that, in rare instances, the distinction between polyclonal and monoclonal kappa free light chains migrating as a ladder-banding pattern may be equivocal.
我们报告了一例病例，其中κ游离轻链导致经典尿免疫电泳结果难以解读，但免疫固定电泳（IFE）显示存在λ-本斯·琼斯蛋白。通过琼脂扩散法和凝胶过滤色谱后的IFE对尿液进行分析表明，困难是由大量多克隆游离轻链的存在引起的。检查还表明，尽管IFE是更敏感和特异的技术，但对浓缩尿样进行IFE时，除非将浓染模式稀释并重测，否则特别容易出现误判。样品稀释过程提供了一种滴定抗原和抗体浓度的方法，使特定条件下的模式在凝胶上可见。该检查还表明，在某些稀释度下，多克隆游离轻链可能以所谓的阶梯状构型与寡克隆带以相同方式迁移。从凝胶色谱分离的单体和二聚体部分均观察到这些条带，这与该模式在很大程度上与分子等电点相关的报道一致。我们推测，在极少数情况下，以阶梯状条带模式迁移的多克隆和单克隆κ游离轻链之间的区分可能不明确。
