Fluorescence of beta-2-microglobulin in the spent dialysate

Abstract

The aim of the study was to determine if fluorescence chromatography can be used to measure modified beta-2-microgobulin (B2M) from the spent dialysate. Amyloid B2M is the main pathogenic component of dialysis-related amyloidosis. This component is in our sphere of interest being one of the fluorescent advanced glycation end products (AGE). AGEs are potential uremic toxins that can cause amyloidosis and cardiovascular problems in chronic kidney failure patients. Two haemodialysis patients with high levels of B2M were selected for this study. Their spent dialysate samples were collected 10 minutes after the start of the dialysis process and less hydrophilic compounds were concentrated using solid phase extraction (SPE) column. Sediment from the concentrate and spent dialysate were analysed with electrospray ionisation mass spectrometer (ESI-MS) MicrOTOF-Q II coupled to high pressure liquid chromatography (HPLC) Dionex UltiMate 3000 RS. The sediment was analysed with Poroshell 120 EC-C18 column and spent dialysate with Kinetex C18 100A column. MagTran was used to interpret mass spectra. Brown coloured fluorescent sediment of the concentrate was identified as amyloid B2M on the basis of MS and fluorescence spectra. AGE modified B2M was also found from spent dialysate. However the fluorescence intensity was very low compared to overall fluorescence of spent dialysate. In summary, the study revealed that the fluorescence of AGE modified B2M is possible to detect in spent dialysate. However, the measuring system needs high selectivity and sensitivity for detection due to low contribution of AGE modified B2M to overall fluorescence.