The expression of carbohydrate antigens in activated T cells and in autoimmune diseases.

Cell surface carbohydrate antigens have been implicated in cell differentiation and maturation and may play a role in immunoregulation. The expression of carbohydrates in peripheral blood lymphocytes (PBL) was studied by double immunofluorescence flow cytometry, using MoAbs CT1 and CT2 but only a small proportion of cells bound these MoAbs. MoAbs CT1, CT2 and the lectin vicia villosa (VV) which share specificity for Gal NAc were then used to examine lymphocytes from patients with systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), Behcet's disease (BD) and IgA nephropathy. A significant increase in MoAbs CT1 CT2 and VV binding CD4 or CD8 cells was found only with lymphocytes from patients with SLE. However, MoAbs CT or VV binding lymphocytes from healthy subjects were significantly up-regulated by activation with a mitogen (PHA), cross-linked anti-CD3 MoAb or a common antigen (65kDa heat shock protein), suggesting that an increased proportion of T cells expressing these carbohydrates results from any of the three types of lymphocyte activating agents. Inhibition studies were then carried out to determine the relationship between the MoAbs CT1 and CT2, VV and GalNAc. Indeed, VV binding to T cells was significantly inhibited by either MoAbs CT1 or CT2, or GalNAc but not GlucNAc, suggesting that VV shares a common binding site with MoAb CT and that GalNAc may constitute one of the sugar receptors. Investigations of lymphocytes from adult peripheral blood in health and disease suggest that carbohydrate antigens may play a role in activation and immunoregulation.