M蛋白对免疫透射比浊法和免疫散射比浊法检测免疫球蛋白的干扰

摘要

Objective To investigate the interference of monoclonal immunoglobulin (M protein) to immunoglobulin determination by immunoturbidimetry and nephelometry. Methods A total of 25 healthy subjects (healthy control group) and 54 patients with different concentrations and different types of M proteins (20 cases of IgG, 16 cases of IgA and 18 cases of IgM) were enrolled. Their serum specimens were collected. IgG, IgA and IgM were determined by immunoturbidimetry and nephelometry. The interference of M protein to the other immunoglobulins was evaluated through interference and recovery experiments. Results The results of IgG, IgA and IgM determinations by nephelometry were higher than those by immunoturbidimetry (P＜0.05). The relative differences of immunoturbidimetry and nephelometry for IgG and IgM determinations in healthy control group were4.86％ and-1.00％, respectively, which were less than allowable total error (TEa). However, the relative difference for IgA (15.42％) was higher than TEa. For IgG type and IgM type M protein patients, the IgG and IgM results' relative differences between the 2 methods were 14.38％ and 4.06％, respectively, which were higher than those in healthy control group (P＜0.05). However, for IgA type M protein patients, the relative difference was 11.95％, which was lower than that in healthy control group (P＜0.05). When IgG level of IgG type M protein was ≥35.13 g/L, the IgA recovery results' difference (Diff％) for IgA was near or over TEa by immunoturbidimetry.When IgG level reached 43.64 g/L, the Diff％ for IgM was lower than TEa by immunoturbidimetry. The same level of Ig G type M protein did not show obvious interference effect on nephelometry. For immunoturbidimetry, Ig A and IgM type M proteins interfered on IgG determination, and the Diff％ was higher than IgG corresponding TEa. However, for nephelometry, the relative high levels of IgA and IgM interfered on IgG determination. For either immunoturbidimetry or nephelometry, there was interference of IgA type M protein on IgM determination or IgM type M protein on IgA determination, and their Diff％ were higher than IgM and IgA corresponding TEa, respectively. Conclusions Ig G, Ig A and IgM type M proteins interfere on the other 2 immunoglobulins in same specimens, and the interference depends on M protein level. Nephelometry shows better anti-interference of M protein than immunoturbidimetry.%目的 探讨单克隆免疫球蛋白(M蛋白)对免疫透射比浊法和免疫散射比浊法定量检测免疫球蛋白的干扰作用.方法 收集54例含不同浓度和类型M蛋白的患者血清样本(IgG型M蛋白20例、IgA型M蛋白16例、IgM型M蛋白18例)和25名体检健康者(正常对照组)的血清样本,分别采用免疫透射比浊法和免疫散射比浊法定量检测IgG、IgA、IgM.通过干扰实验及回收实验评估某种类型M蛋白对同一样本中其他类型免疫球蛋白检测的干扰作用.结果 免疫散射比浊法检测IgG、IgA和IgM的结果高于免疫透射比浊法(P＜0.05).免疫散射比浊法和免疫透射比浊法检测正常对照组血清IgG和IgM浓度的相对偏差分别为4.86％、-1.00％,均低于允许总误差(TEa),而检测IgA浓度的相对偏差(15.42％)高于TEa.2种方法检测IgG型、IgM型M蛋白患者血清IgG、IgM浓度的相对偏差分别为14.38％、4.06％,均高于正常对照组(P＜0.05),而检测IgA型M蛋白患者血清IgA浓度的相对偏差(11.95％)低于正常对照组(P＜0.05).IgG型M蛋白血清样本中IgG≥35.13 g/L时,免疫透射比浊法检测IgA的回收结果差异(Diff％)接近或超过其TEa;而IgG浓度达到43.64 g/L时,免疫透射比浊法检测IgM的Diff％仍低于其TEa;相同浓度的IgG型M蛋白对免疫散射比浊法检测IgA和IgM则无明显干扰作用.IgA和IgM型M蛋白均会干扰免疫透射比浊法检测IgG,并使Diff％超过其TEa;而相对较高水平的IgA和IgM型M蛋白会干扰免疫散射比浊法检测IgG.无论免疫透射比浊法还是免疫散射比浊法,IgA型M蛋白对IgM的检测或IgM型M蛋白对IgA的检测均有干扰作用,并使其Diff％超过相应的TEa.结论 IgG型、IgA型和IgM型M蛋白对免疫透射比浊法和免疫散射比浊法检测其他2种免疫球蛋白均有干扰作用,且呈浓度依赖性.免疫散射比浊法抗M蛋白干扰的能力可能优于免疫透射比浊法.