We examined the effects ofruscogenin glycoside (Lm-3), isolated from Liriope muscari, on lymphocyte adhesion to extracellular matrix. Adhesion of Jurkat cells activated by anti-CD3 to type I collagen was inhibited by Lm-3 in a concentration- and time-dependent manner. Lm-3 also inhibited the cell attachment to Žbronectin and laminin. However, the saponin did not in uence anti-CD3-induced cell proliferation and Mn2+-induced adhesion. Protein kinase C activator, phorbol 12,13-dibutyrate, signiŽ cantly enhanced, while its inhibitor, chlorpromazine, almost completely blocked, the adhesion of anti-CD3-activated Jurkat cells to collagen. Against phorbol 12,13-dibutyrate-activated Jurkat cells, Lm-3 treatment, either before or after activation, signiŽ cantly inhibited the cell adhesion to collagen. Lm-3 also inhibited the adhesion activated by both anti-CD3 and phorbol 12,13-dibutyrate. Similar inhibition by Lm-3 of the phorbol 12,13-dibutyrate-induced adhesion to collagen was also observed in lymphocytes freshly isolated from mice with contact dermatitis. Furthermore, Lm-3 signiŽ cantly decreased the leucocyte accumulation in an animal model of experimental pleurisy. These results suggest that the blockade of lymphocyte adhesion to extracellular matrix through interference with the protein kinase C pathway may be one of the mechanisms by which Lm-3 exerts anti-in ammatory activity.