A re-evaluation of the lipid-bound sialic acid determination.

The origin of serum sialic acid measured in the lipid-bound sialic acid determination reported by Katopodis et al. (1980) was investigated in detail. By varying the experimental conditions of sample preparation the protein, lipid and sialic acid contents of the methanol-water extract obtained from human sera were analyzed and compared in healthy controls and cancer patients. Using polyacrylamide gel electrophoretic and gel chromatographic methods it has been shown that most of the lipid-bound sialic acid was attributed to the acid alpha 1-glycoprotein (orosomucoid) fraction of human sera. Based on these observations a re-evaluation of the molecular background of the LBSA determination seems to be necessary.