Background/Aims: A misfolded β2-microglobulin (β2m) is a principle component in dialysis-related amyloidosis. However, no such conformational variant of β2m has yet been reported in a clinical setting. Capillary electrophoresis is a tool that can identify the conformational variant of β2m. Methods: Capillary electrophoresis was used to measure a transitional intermediate from native β2m (N-β2m) to the amyloid β2m. This technique was utilized to assay for intermediate β2m (I-β2m) in serum from 31 hemodialysis (HD) patients before and after HD, 5 patients with non-dialysis chronic renal failure (CRF), and 5 healthy persons. Results: The predialysis values of serum I-β2m and N-β2m were 2.7 ± 1.4 and 29.4 ± 6.8 mg/l, respectively, in the HD patients. The presence of serum I-β2m correlated weakly with the total serum β2m concentration in all HD patients. The serum N-β2m concentration decreased significantly during two types of dialysis treatment: by 32.8% on HD using a polymethylmethacrylate (PMMA) membrane and by 71.2% on online hemodiafiltration (HDF) with a polysulfone (PS) membrane. On the other hand, a dialysis-associated change in serum I-β2m varied from –36.4 to +203.5% in HD patients using PMMA and from –70.8 to +62.5% in online HDF patients using PS. Moreover, a rebound β2m profile suggested that I-β2m might be immobilized in the extracellular space. Conclusion: This study demonstrated that two or three conformational isomers of β2m were probably ubiquitously recognized in human serum. Though no progressive increase in serum I-β2m concentration could be found along with HD, this study shows a significantly poor removal of I-β2m in comparison to N-β2m in patients receiving ongoing dialysis treatment, even with online HDF.

Keywords:
Capillary electrophoresis, β2-Microglobulin, intermediate, Amyloidosis, dialysis-related
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