Jain Pallavi, Choudhary Reeta, Harith Arun Kumar, Yadav Charu
Department of Biochemistry, Medanta-The Medicity, Gurgaon, India.
Indian J Clin Biochem. 2022 Apr;37(2):247-249. doi: 10.1007/s12291-020-00929-y. Epub 2021 Apr 8.
Multiple myeloma is characterized by the presence of M-protein (monoclonal) in blood or urine. These proteins are immunoglobulins which are produced by a clone of abnormally proliferating B-lymphocytes and/or plasma cells. To evaluate M-protein, serum protein electrophoresis (SPEP) is used where a single band, known as M-band is seen. This band is usually seen in the gamma globulin region. However, in rare entities like biclonal gammopathy, two M-bands appear simultaneously at different positions on SPEP which may be attributed to the clonal expansion of two different neoplastic cell lines. Here, we describe an atypical case of IgA-kappa multiple myeloma, where two M-bands (one in the beta region and one in the gamma globulin region) were found during SPEP. This simulated a picture of biclonal gammopathy. However the monoclonal nature of this M-protein was proved by performing immunofixation electrophoresis (IFE). Further, we put across images to explain how IFE helps in differentiating between apparent and true biclonality.
多发性骨髓瘤的特征是血液或尿液中存在M蛋白（单克隆）。这些蛋白质是免疫球蛋白，由异常增殖的B淋巴细胞和/或浆细胞克隆产生。为了评估M蛋白，使用血清蛋白电泳（SPEP），会出现一条单一的条带，称为M带。这条带通常出现在γ球蛋白区域。然而，在双克隆丙种球蛋白病等罕见情况下，在SPEP上会同时出现两条不同位置的M带，这可能归因于两种不同肿瘤细胞系的克隆性扩增。在此，我们描述了一例非典型的IgA-κ多发性骨髓瘤病例，在SPEP过程中发现了两条M带（一条在β区域，一条在γ球蛋白区域）。这模拟了双克隆丙种球蛋白病的表现。然而，通过进行免疫固定电泳（IFE）证实了这种M蛋白的单克隆性质。此外，我们展示图像来说明IFE如何有助于区分表观双克隆性和真正的双克隆性。
