González González J B, García Delgado R, Cámara Sáez E, Ortiz Maslloréns F
Departamento de Inmunología, Fundación Jiménez Díaz, Madrid.
Rev Clin Esp. 1996 Aug;196(8):529-35.
A study was conducted to investigate the relationships between the characteristics of IgA paraprotein and the clinical findings in a group of 196 patients. In 19 cases IgA paraprotein was associated with another monoclonal immunoglobulin (IgG or IgM); the other 177 patients had a single IgA paraprotein; 145 of them corresponded to multiple myeloma (MM) and the other 32 to other diagnostics. Class and type of paraproteins were identified by immunoelectrophoresis and subclass by an enzyme-immunoassay specifically developed for this study. The degree of polymerization of the protein was determined by gel filtration; quantitation of monoclonal IgA and polyclonal IgG and IgM was obtained by kinetic nephelometry. Out of 196 paraproteins, 96.4% were classified in IgA1 subclass and only 3.6% in IgG2. In 14 cases, all of them diagnosed with MM, monoclonal IgA in serum was associated with Bence-Jones protein; in more than 78% of them light chains corresponded to type lambda, whereas type kappa predominated (over 60%) in cases without Bence-Jones protein in serum. Significantly higher serum levels of monoclonal IgA were associated with the diagnosis of myeloma, with type kappa paraproteins, and with the presence of Bence-Jones protein in serum. The cases with two paraproteins (IgA and IgG or IgM) had significantly lower serum levels of IgA, with comparable levels of total paraprotein (the addition of both monoclonal immunoglobulins). Serum levels of polyclonal IgG and IgM, which appeared decreased in cases of MM, were normal in cases with other conditions. In all these cases, monoclonal IgA showed a monomeric character, whereas relevant amounts of polymerized IgA paraprotein was found in almost a third part of myeloma cases, particularly in those with higher serum levels of paraprotein, or when paraprotein belonged to type kappa. The 5 IgA2 paraproteins analyzed had a polymeric character. In conclusion, a detailed, both qualitative and quantitative, analysis of IgA paraproteins can lead to a better knowledge of conditions associated with their presence and at the same time provides useful data for a clinical evaluation of patients.
一项研究旨在调查196例患者中IgA副蛋白特征与临床发现之间的关系。19例患者的IgA副蛋白与另一种单克隆免疫球蛋白（IgG或IgM）相关；其余177例患者仅有单一的IgA副蛋白；其中145例符合多发性骨髓瘤（MM）诊断，另外32例为其他诊断。通过免疫电泳鉴定副蛋白的类别和类型，通过专门为本研究开发的酶免疫测定法鉴定亚类。通过凝胶过滤测定蛋白质的聚合程度；通过动态散射比浊法对单克隆IgA以及多克隆IgG和IgM进行定量。在196种副蛋白中，96.4%归类为IgA1亚类，仅3.6%为IgG2。在14例均诊断为MM的患者中，血清中的单克隆IgA与本周氏蛋白相关；其中超过78%的轻链对应于λ型，而在血清中无本周氏蛋白的病例中κ型占主导（超过60%）。血清中单克隆IgA水平显著升高与骨髓瘤诊断、κ型副蛋白以及血清中本周氏蛋白的存在相关。有两种副蛋白（IgA和IgG或IgM）的病例血清IgA水平显著较低，而总副蛋白水平（两种单克隆免疫球蛋白之和）相当。MM病例中多克隆IgG和IgM的血清水平似乎降低，而其他情况的病例中则正常。在所有这些病例中，单克隆IgA呈单体特征，而在几乎三分之一的骨髓瘤病例中发现了相当数量的聚合型IgA副蛋白，特别是在那些副蛋白血清水平较高或副蛋白属于κ型的病例中。分析的5种IgA2副蛋白具有聚合特征。总之，对IgA副蛋白进行详细的定性和定量分析可以更好地了解与其存在相关的情况，同时为患者的临床评估提供有用的数据。
