Identification of a spurious band on serum protein electrophoresis induced by ethanol treatment

Background: Treatment of serum with ethanol at 100 ml/l eliminating fibrinogen from electrophoretic pattern produces an additional band at α₂/β junction. This study is to determine the source and the nature of this artifact. Methods: The supernatant after ethanol precipitation was used for electrophoresis. Protein concentrations of each fraction in ethanol- and saline-treated samples were compared, and immunofixation electrophoresis (IFE) to identify transferrin, C3, and LDL was performed. C3 IFE was also conducted for fresh sera and sera stored for 2 weeks. Results: The artificial band at α₂/β junction was identified in ethanol-treated sera but not in saline-treated sera. Protein concentration in the β fraction was reduced after ethanol treatment as compared to saline-treated samples (n = 10, p < 0.01). The spurious band at α₂/β junction was recognized in C3 IFE. C3 IFE also showed a band at α₂/β junction in samples stored for 2 weeks. Conclusions: Ethanol treatment of serum creates an artificial band with C3 immunoreactivity at α₂/β junction. This could be due to the accelerated hydrolysis of C3 by ethanol treatment. Laboratories using ethanol to evaluate a possible fibrinogen band should be aware of this phenomenon, and the serum protein electrophoretic pattern after ethanol treatment should only be used to rule out fibrinogen.