Figure 3.

Representative MALDI-QIT-TOF MS spectra of desialylated haptoglobin N-glycans in sera of healthy subjects (A) and patients with liver cirrhosis (B) and HCC (C). Glycans were desialylated by neuraminidase, purified with PGC tips, and permethylated. The nonfucosylated bi- and triantennary complex-type glycans (m/z 2070.07 and 2519.28) were the most abundant structures in healthy subjects and patients with cirrhosis and HCC. Both the triantennary and tetra-antennary glycans were highly elevated in HCC compared to their abundance in normal and cirrhosis samples. The bifucosylated glycans, with both core and antennary fucosylation, were predominantly identified in HCCs but were absent in healthy subjects. Patients with cirrhosis showed a distinctly low abundance of bifucosylated triantennary (m/z 2867.48) glycan. The composition of each glycan is confirmed with both MS/MS analysis and knowledge of their biosynthesis pathways (red triangle, Fuc; blue square, GlcNAc; green circle, Man; yellow circle, Gal).