Glycosylation patterns of selected proteins in individual serum and cerebrospinal fluid samples

A method we previously developed has been applied to the determination of the glycosylation pattern of specific proteins in biological samples. Six proteins (alpha-1-antitrypsin, transferrin, haptoglobin, C1 inhibitor, alpha-1 acid glycoprotein, and immunoglobulin G) were studied in serum samples from five individuals and cerebrospinal fluid (CSF) samples from three individuals, to investigate the expected normal distribution of glycosylation patterns and to assess whether this methodology can be used to discriminate between samples from different individuals. For serum samples, the differences were shown to be small, while much larger differences were found for the CSF samples, with a greater number of glycoforms present. This can be linked to the occurrence of differential glycosylation in proteins expressed in the brain compared with proteins expressed elsewhere in the body. The developed method could distinguish differences in the glycosylation pattern of specific proteins in the individual samples, which was not reflected in the glycan content of total CSF. This is the first time that the glycoforms of several of these proteins have been investigated in CSF.