O-glycosylation of NnTreg lymphocytes recognized by the Amaranthus leucocarpus lectin.

O-glycosidically-linked glycans have been involved in development, maturation, homing, and immune regulation in T cells. Previous reports indicate that Amaranthus leucocarpus lectin (ALL), specific for glycans containing galactose-N-acetylgalactosamine and N-acetylgalactosamine, recognizes human naïve CD27(+)CD25(+)CD4(+) T cells. Our aim was to evaluate the phenotype of CD4(+) T cells recognized by ALL in peripheral blood mononuclear cells obtained from healthy volunteers. CD4(+) T cells were isolated by negative selection using magnetic beads-labeled monoclonal antibodies; the expression of T regulatory cell phenotypic markers was assessed on ALL-recognized cells. In addition, IL-4, IL-10, IFN-γ, and TGF-β intracellular production in ALL (+) cells was also evaluated. The analyses of phenotypic markers and intracellular cytokines were performed through flow cytometry. ALL-recognized CD4(+) T cells were mainly CD45RA(+), CCR7(+) cells. Although 52 ± 10% CD25(+)Foxp3(+) cells were positive to ALL, only 34 ± 4% of ALL (+) cells corresponded to CD25(+)Foxp3(-) cells. Intracellular cytokines in freshly obtained ALL (+)CD4(+) T cells exhibited 8% of IL-4, 15% of IL-10, 2% of IFN-γ, and 15% of TGF-β, whereas ALL (-)CD4(+) T cells depicted 1% of IL-4, 2% of IL-10, <1% of IFN-γ, and 6% of TGF-β. Our results show that galactose-N-acetylgalactosamine and N-galactosamine-bearing CD4(+) T cells expressed phenotypic markers of NnTreg cells.