Comparative glycomics of leukocyte glycosaminoglycans

Glycosaminoglycans (GAGs) vary widely in disaccharide and oligosaccharide content in a tissue-specific manner. Nonetheless, there are common structural features, such as the presence of highly sulfated non-reducing end domains on heparan sulfate (HS) chains. Less clear are the patterns of expression of GAGs on specific cell types. Leukocytes are known to express GAGs primarily of the chondroitin sulfate (CS) type. Little is known, however, regarding the properties and structures of the GAG chains, their ranges of variability among normal subjects, and changes in structure associated with disease conditions. We isolated peripheral blood leukocyte populations from four human donors and extracted GAGs. We determined the relative and absolute disaccharides abundances for HS and CS GAG classed using size exclusion chromatography-mass spectrometry (SEC-MS). We found that all leukocytes express HS chains with level of sulfation more similar to heparin than to organ-derived HS. The levels of HS expression follows the trend T Cells, B cells>monocytes, NK cells>polymorphonuclear leukocytes (PMNs). In addition, CS abundances were considerably higher than total HS but varied considerably in a leukocyte cell type specific manner. Levels of CS were higher for myeloid lineage cells (PMNs, monocytes) than for lymphoid cells (B, T, NK cells). This information establishes the ranges of GAG structures expressed on normal leukocytes and necessary for subsequent inquiry into disease conditions.