The effect of various vitamin E derivatives on the urokinase-plasminogen activator system of ovine macrophages and neutrophils

The effect of vitamin E derivatives on the urokinase-plasminogen activator (u-PA) system of resting and phorbol myristate acetate (PMA)-activated ovine macrophages and neutrophils were investigated. Blood monocyte–macrophages and neutrophils were isolated from twenty-four animals. Macrophages or neutrophils were cultured in vitro for 3 or 24 h with or without various vitamin E derivatives: free α-tocopherol (α-T), α-tocopheryl acetate (α-TA), or α-tocopheryl succinate (α-TS). Following incubation, cells were stimulated with 80 μM-PMA. Total cell-associated u-PA, membrane-bound u-PA and free u-PA binding sites were determined before and after stimulation with PMA. Results showed that none of the vitamin E derivatives had any effect (P>0·05) on the u-PA system of resting monocyte–macrophages or neutrophils. In contrast, α-TS, but not α-TA or α-T, increased (P0·05) on total u-PA and membrane-bound u-PA activities of macrophages and neutrophils cultured in the presence of 4-phorbol 12,13 didecanoate, a phorbol ester that does not activate protein kinase (PK) C. Addition of H7 (1-(5-isoquinolinesulfonyl)-2-methylpiperazine dihydrochloride), which is a potent inhibitor of both PK A and C, completely abolished the effect of α-TS on total cell-associated u-PA and membrane-bound u-PA of PMA-activated macrophages and neutrophils. Addition of HA1004 (N-(2-quanidinoethyl)-5-isoquinoline sulfonamide hydrochloride), which is a potent PK A but a weak PK C inhibitor, had no effect (P>0·05) on total cell-associated u-PA and membrane-bound u-PA of PMA-activated macrophages and neutrophils cultured in the presence of α-TS. Thus, PK C modulates the effect of α-TS on the u-PA system of ovine macrophages and neutrophils.