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 A L L + 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 A L L + cells corresponded to CD25⁺Foxp3 ^- cells. Intracellular cytokines in freshly obtained A L L + CD4 ⁺ T cells exhibited 8% of IL-4, 15% of IL-10, 2% of IFN- γ, and 15% of TGF- β, whereas A L L - 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.