Abstract：
BACKGROUND: We report a case of a patient with immunoglobulin A multiple myeloma associated with a masked kappa light chain. Serum immunofixation showed a monoclonal band in the IgA heavy chain lane without corre-spondence with the light chain and a monoclonal band in total kappa light chain lane without correspondence with the heavy chain.
METHODS: To distinguish between heavy chain disease and immunoglobulin with \"masked\" light chains, two tubes containing the patient\'s serum were incubated with a very high concentration of anti-total kappa and anti-total lambda antisera for 48 hours at 4°C in order to facilitate immunoprecipitation of the involved light chain. After centrifugation, the supernatant was analyzed by using the IFs method on the Hydrasys 2 Scan Focusing Sebia® without dilution. Then we applied the anti-IgA, anti-total kappa and anti-total lambda antisera.
RESULTS: The serum immunofixation test of the sample treated with a high concentration of anti-total kappa showed the disappearance of the monoclonal bands corresponding to IgA heavy chain lane and kappa light chain lane, indicating that precipitation had occurred and that the IgA did have kappa light chains that could not be detected by the standard immunofixation protocol. The serum immunofixation test of the sample treated with anti-total lambda showed the disappearance of the polyclonal background in lambda light chain lane, confirming that the precipitation with lambda light chains according to the previously mentioned protocol has done well.
CONCLUSIONS: This case illustrates some of the difficulties encountered and the corrective actions that can be taken for the detection of immunoglobulins with masked light chains.
METHODS: To distinguish between heavy chain disease and immunoglobulin with \"masked\" light chains, two tubes containing the patient\'s serum were incubated with a very high concentration of anti-total kappa and anti-total lambda antisera for 48 hours at 4°C in order to facilitate immunoprecipitation of the involved light chain. After centrifugation, the supernatant was analyzed by using the IFs method on the Hydrasys 2 Scan Focusing Sebia® without dilution. Then we applied the anti-IgA, anti-total kappa and anti-total lambda antisera.
RESULTS: The serum immunofixation test of the sample treated with a high concentration of anti-total kappa showed the disappearance of the monoclonal bands corresponding to IgA heavy chain lane and kappa light chain lane, indicating that precipitation had occurred and that the IgA did have kappa light chains that could not be detected by the standard immunofixation protocol. The serum immunofixation test of the sample treated with anti-total lambda showed the disappearance of the polyclonal background in lambda light chain lane, confirming that the precipitation with lambda light chains according to the previously mentioned protocol has done well.
CONCLUSIONS: This case illustrates some of the difficulties encountered and the corrective actions that can be taken for the detection of immunoglobulins with masked light chains.
摘要：
背景：我们报告了1例患者的免疫球蛋白A多发性骨髓瘤与κ轻链被掩蔽相关。血清免疫固定显示IgA重链泳道中的单克隆带与轻链无对应关系，总κ轻链泳道中的单克隆带与重链无对应关系。
方法：为了区分重链疾病和具有“掩蔽”轻链的免疫球蛋白，将装有患者血清的两个试管与非常高浓度的抗总κ和抗总λ抗血清在4°C下孵育48小时,以促进相关轻链的免疫沉淀.离心后，通过在不稀释的Hydrasys2扫描聚焦Sebia®上使用IFs方法分析上清液。然后我们用了抗IgA,抗总κ和抗总λ抗血清。
结果：用高浓度抗总κ处理的样品的血清免疫固定试验显示，与IgA重链泳道和κ轻链泳道相对应的单克隆条带消失，表明已经发生沉淀，并且IgA确实具有通过标准免疫固定方案无法检测到的κ轻链。用抗总λ处理的样品的血清免疫固定测试显示λ轻链泳道中的多克隆背景消失，确认根据先前提到的方案用λ轻链进行的沉淀已经完成得很好。
结论：该案例说明了在检测具有掩蔽轻链的免疫球蛋白时遇到的一些困难和可以采取的纠正措施。
方法：为了区分重链疾病和具有“掩蔽”轻链的免疫球蛋白，将装有患者血清的两个试管与非常高浓度的抗总κ和抗总λ抗血清在4°C下孵育48小时,以促进相关轻链的免疫沉淀.离心后，通过在不稀释的Hydrasys2扫描聚焦Sebia®上使用IFs方法分析上清液。然后我们用了抗IgA,抗总κ和抗总λ抗血清。
结果：用高浓度抗总κ处理的样品的血清免疫固定试验显示，与IgA重链泳道和κ轻链泳道相对应的单克隆条带消失，表明已经发生沉淀，并且IgA确实具有通过标准免疫固定方案无法检测到的κ轻链。用抗总λ处理的样品的血清免疫固定测试显示λ轻链泳道中的多克隆背景消失，确认根据先前提到的方案用λ轻链进行的沉淀已经完成得很好。
结论：该案例说明了在检测具有掩蔽轻链的免疫球蛋白时遇到的一些困难和可以采取的纠正措施。
