Sialyl Glycan Expression on T Cell Subsets in Asthma: a correlation with disease severity and blood parameters

Memory T helper (Th) and regulatory T (Treg) cells play key roles in asthma. Certain sialyl carbohydrate determinants for selectins profoundly affect the migratory properties of memory Th cells, and the suppressive function of Treg cells. Previous studies have shown that the proportion of CCR4(+) memory Th cells expressing sialyl 6-sulfo Lewis X (Le(X)) is elevated in asthma patients. We aim to investigate the roles of different sialyl glycans on T cell subsets in asthma. Using flow cytometry, we assessed the expression of three sialyl glycans, sialyl 6-sulfo Le(X), cyclic sialyl 6-sulfo Le(X), and sialyl Le(X) on memory Th and Treg cells, in the peripheral blood of asthmatic children. We also assessed the relationships between glycan-expressing cell percentages and asthma clinical parameters. Compared with controls, asthmatic children showed higher proportions of memory Th cells expressing sialyl Le(X) and sialyl 6-sulfo Le(X). The proportions of memory Th cells with sialyl 6-sulfo Le(X) and cyclic sialyl 6-sulfo Le(X) expression in asthmatic children correlated with absolute eosinophil count and IgE level, respectively. Children with moderate-to-severe asthma had lower numbers of sialyl Le(X) positive Treg cells. Our study suggests that sialyl glycans on T cells may play important roles in the pathogenesis of asthma.