SM-15178

The role of P selectin in the accumulation of neutrophils at acute dermal inflammatory sites induced by chemoattractants, LTB4 and IL-8 was investigated in the mouse. A mouse P-selectin-human IgG chimera bound to mouse neutrophils in vitro in a calcium-dependent manner, as detected by flow cytometry. A rat monoclonal antibody (mAb) against mouse P-selectin, RB40.34 abolished P-selectin-IgG chimera binding to mouse neutrophils, but a control antibody did not. Intradermal injection of LTB4 at a dose of 100 ng/site caused neutrophil accumulation to increase by 3-4 fold, as detected by measuring myeloperoxidase activity. Neutrophil extravasation to perivascular tissue was detected by histochemical observation. The intravenous injection of RB40.34 or the specific LTB4 antagonist, SM-15178, at doses at 5 mg/kg attenuated the accumulation of neutrophils by 55.6% and 70.3%, respectively, but a control antibody showed no effect. Similarly, intradermal administration of IL-8 at a dose of 5 microg/site induced significant neutrophil migration into the interstitial tissue of the skin, as followed by measuring myeloperoxidase activity and histopathologic analysis. The intravenous injection of RB40.34 at a dose of 5 mg/kg reduced the neutrophil accumulation by 59.2% in contrast, a control antibody showed no effect. To our knowledge, this is the first direct demonstration that P-selectin plays a substantial role in LTB4- and IL-8-induced neutrophil accumulation in mouse skin.