Tate Jillian R, Mollee Peter, Dimeski Goce, Carter Andrew C, Gill Devinder
Chemical Pathology Department, Queensland Health Pathology Service, Royal Brisbane and Princess Alexandra Hospitals, Brisbane, Australia.
Clin Chim Acta. 2007 Feb;376(1-2):30-6. doi: 10.1016/j.cca.2006.07.011. Epub 2006 Jul 14.
Measurement of serum free light chains (FLC) is useful for the diagnosis and monitoring of monoclonal light-chain diseases. It has been suggested that there will be widespread replacement of urine Bence Jones protein measurement by serum FLC assay. We report on our experience with the assay during monitoring of light-chain myeloma (LCMM) and AL amyloidosis (AL).
Serum FLC immunoassay, serum and/or urine protein electrophoresis and immunofixation were performed on serial samples during monitoring of LCMM. Recovery and immunoreactivity of FLC were tested by sample dilution. Assay precision was determined by repeat assay of samples over several reagent lots.
In one of 23 patients with LCMM there was non-reaction of a monoclonal kappa FLC with some reagent lots and the assay did not indicate disease relapse. Samples showed non-linear, non-parallel immunoreactivity on dilution. Several tested monoclonal FLC gave lower values at the assay starting dilution compared with higher sample dilution and non-parallel dose-response curves. The median between-reagent lot variation for FLC measurement was 19-20% CV.
Laboratory staff and clinicians need to be aware of the potential for non-reactivity of individual monoclonal FLC, and the effects of dilution and precision on FLC values and their interpretation.
血清游离轻链（FLC）检测对于单克隆轻链疾病的诊断和监测很有用。有人提出血清FLC检测将广泛取代尿本-周蛋白检测。我们报告了在监测轻链骨髓瘤（LCMM）和AL淀粉样变性（AL）期间使用该检测方法的经验。
在监测LCMM期间，对系列样本进行血清FLC免疫测定、血清和/或尿蛋白电泳及免疫固定。通过样本稀释检测FLC的回收率和免疫反应性。通过对多个试剂批次的样本进行重复检测来确定检测精密度。
在23例LCMM患者中，有1例患者的单克隆κFLC与某些试剂批次无反应，且检测未显示疾病复发。样本在稀释时显示出非线性、非平行的免疫反应性。与更高的样本稀释度相比，几种检测的单克隆FLC在检测起始稀释度时的值较低，且剂量反应曲线不平行。FLC检测的试剂批次间变异中位数为19 - 20%CV。
实验室工作人员和临床医生需要意识到单个单克隆FLC无反应的可能性，以及稀释和精密度对FLC值及其解读的影响。
