Serum and Plasma Immunoglobulin G Fc N‑Glycosylation Is Stable during Storage

Immunoglobulin G
(IgG) glycosylation is studied in biological samples
to develop clinical markers for precision medicine, for example, in
autoimmune diseases and oncology. Inappropriate storage of proteins,
lipids, or metabolites can lead to degradation or modification of
biomolecular features, which can have a strong negative impact on
accuracy and precision of clinical omics studies. Regarding the preservation
of IgG glycosylation, the range of appropriate storage conditions
and time frame is understudied. Therefore, we investigated the effect
of storage on IgG Fc N-glycosylation in the commonly analyzed biofluids,
serum and plasma. Short-term storage and accelerated storage stability
were tested by incubating samples from three healthy donors under
stress conditions of up to 50 °C for 2 weeks using −80
°C for 2 weeks as the reference condition. All tested IgG glycosylation
featuressialylation, galactosylation, bisection, and fucosylationremained
unchanged up to room temperature as well as during multiple freeze–thaw
cycles and exposure to light. Only when subjected to 37 °C or
50 °C for 2 weeks, galactosylation and sialylation subtly changed.
Therefore, clinical IgG glycosylation analysis does not rely as heavily
on mild serum and plasma storage conditions and timely analysis as
many other omics analyses.