sLex is not responsible for the interaction of sLex-positive memory T lymphocytes with E-selectin

E-selectin in an adhesion molecule that is transiently and exclusively expressed on endothelial cells in response to inflammatory cytokines. In addition, E-selectin participates in the initial interaction of leucocytes with activated endothelial cells. This role of E-selectin in cell adhesion has made it a potential target for modulation of inflammatory processes that, for example, are occurring in autoimmune diseases such as rheumatoid arthritis. Although on granulocytes the ligand for E-selectin has been identified as the tetrasaccharide sialyl Lewis x (sLex), the molecular nature of this ligand on T lymphocytes has not yet been identified. In the present study, it was shown by fluorescence-activated cell sorter (FACS) analysis with the anti-sLex antibody CSLEX1 that T lymphocytes stimulated with phytohaemagglutanin (PHA), interleukin-2 (IL-2) and transforming growth factor-beta 1 (TGF-beta 1) expressed sLex. Furthermore, in a cell adhesion assay these activated T cells of the memory phenotype bound specifically to E-selectin-transfected Chinese hamster ovary (E-CHO) cells. This adhesion could be blocked with an anti-E-selectin antibody but not with CSLEX1. In the same assay, the interaction of sLex-positive U937 cells with the E-CHO cells could be inhibited both with anti-E-selectin and CSLEX1 antibodies. From these results it can be inferred that sLex on activated T lymphocytes is not responsible for the interaction with E-selectin. Rather, these results suggest that stimulated T lymphocytes express an additional E-selectin ligand(s) with much higher avidity for E-selectin than sLex.