Sialyl Lewis X moiety on rat polymorphonuclear leukocytes responsible for binding to rat E-selectin

We investigated the presence of the carbohydrate ligand for E-selectin on the cell surface of rat polymorphonuclear leukocytes (PMN). Rat PMN, isolated from peripheral blood, adhered to recombinant rat E-selectin-coated microplates. The adhesion was inhibited either by an anti-rat E-selectin monoclonal antibody (MAb), a sialyl Lewis X (SLex) oligosaccharide or neuraminidase digestion. FACS analysis revealed the expression of SLex as well as other adhesion molecules such as L-selectin, CD11a, CD11b and CD18 on the cell surface of rat PMN. The binding of an anti-SLex MAb KM93 to rat PMN was inhibited competitively by a SLex but not by a Lewis X (Lex). The reactivities of two anti-SLex MAbs, KM93 and CSLEX-1, or an anti-Lex MAb BC90/45 to rat PMN differed from those to human PMN. These results suggest that rat PMN contain the SLex-moiety, which binds to rat E-selectin and is different from that of human PMN.