Jones C, Mermelstein N, Kincaid-Smith P, Powell H, Roberton D
Department of Immunology, Royal Children's Hospital, Melbourne, Australia.
Clin Exp Immunol. 1988 May;72(2):344-9.
This report concerns the relative quantitation of serum polymeric IgA and polymeric IgA subclass concentrations by enzyme immunoassay (EIA). The assay relies on the specific binding of polymeric IgA to secretory component. Competition between pentameric IgM and polymeric IgA for binding to secretory component was observed. Thus, samples were adsorbed for IgM by affinity chromatography before the EIA was performed. The assay was used to determine an age-related range of serum polymeric IgA concentrations and to compare the polymeric IgA concentrations in patients with IgA nephropathy (n = 50) to those of controls (n = 50). The serum concentrations of both polymeric IgA and polymeric IgA1 increased with age reaching adult values of around 12 years of age. Polymeric IgA2 concentrations did not reach adult levels until 18 years of age. The ratio of the polymeric IgA concentration to the total serum IgA concentration was found to be significantly increased in children under 2 years of age compared with those over 4 years of age (Mann-Whitney U-test, P less than 0.01). Patients with IgA nephropathy had significantly increased concentrations of polymeric IgA (P = 0.001) and polymeric IgA1 (P = 0.001) but similar polymeric IgA2 concentrations to controls.
本报告涉及通过酶免疫测定法（EIA）对血清聚合IgA和聚合IgA亚类浓度进行相对定量。该测定法依赖于聚合IgA与分泌成分的特异性结合。观察到五聚体IgM和聚合IgA之间存在与分泌成分结合的竞争。因此，在进行EIA之前，通过亲和色谱法吸附样品中的IgM。该测定法用于确定血清聚合IgA浓度与年龄相关的范围，并比较IgA肾病患者（n = 50）与对照组（n = 50）的聚合IgA浓度。聚合IgA和聚合IgA1的血清浓度均随年龄增长而升高，在12岁左右达到成人水平。聚合IgA2浓度直到18岁才达到成人水平。与4岁以上儿童相比，2岁以下儿童的聚合IgA浓度与总血清IgA浓度之比显著升高（曼-惠特尼U检验，P<0.01）。IgA肾病患者的聚合IgA（P = 0.001）和聚合IgA1（P = 0.001）浓度显著升高，但聚合IgA2浓度与对照组相似。
