Species-specific expression of sialosyl-Le(x) on polymorphonuclear leukocytes (PMN), in relation to selectin-dependent PMN responses.

Sialosyl-Le(x) (SLex) and its positional isomer sialosyl-Le(a) are the epitopes recognized by the lectin domain of E- and P-selectins. Expression of SLex in polymorphonuclear leukocytes (PMN) plays an important role in recruitment of these cells at sites of inflammation through activation of selectins. We studied expression of SLex in PMN of seven mammalian species in comparison with that in humans. Only PMN of humans (no other species) expressed SLex or other lacto-series epitopes such as Le(x) or Le(y). The observed absence of these epitopes in rat PMN seems inconsistent with recent reports that the lung inflammation process in a rat model is inhibited by perfusion of SLex oligosaccharide (Mulligan MS, et al. (1993a) Nature 364:149; (1993b) J Exp Med 178:623). Rat selectins may be able to recognize SLex, even though this epitope is absent in rat PMN.