Alpha-1-microglobulin profile in patients on maintenance hemodialysis and its removal by blood purification.

Alpha-1-microglobulin (A1M), metabolized in renal tubules, plays an important role as a potent antioxidant in human cells. The majority of A1M is present in the blood in free form and in a bound form with IgA dimers, with the free form thought to have antioxidant capacity. However, the dynamics of A1M in chronic kidney disease patients being susceptible to oxidative stress remain unclear. The present study aimed to determine the profile and changes in A1M resulting from blood purification in patients undergoing maintenance hemodialysis (HD) (including hemodiafiltration). Eighteen patients on stable maintenance HD were included in the study. For analysis, residual serum samples were collected from these patients during routine blood tests. A1M was measured using a latex agglutination immunoassay. The abundance of the free and bound forms of A1M was determined by native PAGE. The A1M concentration was 91.58 ± 26.34 mg/L, the percentage of free A1M was 72.62 ± 20.02%. The pre- and postdialysis mean concentration of free A1M were 68.74 ± 29.78 and 52.13 ± 22.48 mg/L, respectively. The mean reduction rate in free A1M after blood purification treatment was 20.49 ± 20.91%, showing the significant difference between pre- and postdialysis concentrations. The predialysis mean concentration of protein-bound A1M was 22.85 ± 15.16 mg/L, with a postdialysis concentration of 24.73 ± 12.82 mg/L. The novel finding of this study is that A1M in patients on maintenance HD exists pre-dominantly in the free form and can be effectively removed by hemodialysis.