Interleukin-One Induced Arachidonic Acid Turnover in Macrophages

Abstract

Recombinant Interleukin-1β (rIL-1β) induced dose-dependent synthesis of PGE₂ and activation of both cell-associated and soluble phospholipase A₂ (PLA₂) in cultured mouse peritoneal macrophages. Kinetic studies showed that rIL-1β was able to induce a 2-fold increase in membrane bound PLA₂ activity in the cells within 1 hour. Elevated levels of PGE₂ were however observed only after 4 hours stimulation of the cells while significant levels of soluble PLA₂ activity were observed only after 16 hours stimulation of the cells. Stimulation with rIL-1β of macrophage cultures pre-labelled with [^l4C]arachidonic acid resulted in a loss of label from both phosphatidyl-choline and phosphatidylinositol in only 10min. which was not observed in control (unstimulated) cultures. These results are indicative that the two phospholipids are the principal source of arachidonic acid for IL-1 induced prostaglandin synthesis.

Key Words:

• Interleukin-1
• macrophage
• prostaglandin E₂
• phospholipase A₂
• phospholipid.