Detection of novel beta 2-microglobulin in the serum of hemodialysis patients and its amyloidogenic predisposition.

Serum from 8 undialyzed patients and 30 dialyzed patients was examined by immunoblotting using anti beta 2-microglobulin (beta 2M) serum after two-dimensional gel electrophoresis (2.DE). One major spot and three minor spots were detected in the ultrafiltrate as well as in the serum. One major spot was determined to be native beta 2M and three minor spots were found to be novel beta 2M. Novel beta 2M had a lower molecular weight (MW) and a higher acidic isoelectric point (pI). Novel beta 2M was recognized in the sera of 5 out of 20 hemodialysis (HD) patients without carpal tunnel syndrome (CTS), 2 of whom had been on HD from 5 to 10 years and 3 for more than 10 years, as well as in the sera of all 10 patients with CTS. By chromatofocusing, pI of novel beta 2M was 5.2, while pI of native beta 2M was 5.7. When the tissue specimen of transverse carpal ligament of 2 HD patients with CTS was examined by immunoblotting after 2.DE, the spot of novel beta 2M was larger than that of native beta 2M. It is possible that some metabolic abnormality of beta 2M occurs through long-term hemodialysis, and it is possible that novel beta 2M might relate to amyloidogenic predisposition.