INTERLEUKIN-4 MODULATION OF PLATELET-DERIVED GROWTH FACTOR-INDUCED SMOOTH-MUSCLE CELL UROKINASE PLASMINOGEN-ACTIVATOR

Platelet-derived growth factor (PDGF) stimulates smooth muscle cell(SM C) migration owing to stimulation of SMC tissue plasminogen activator (t-PA) production. In this study we examined the effects of the T-cell lymphokine interleukin-4 (IL-4) on PDGF induction of human aortic SMC antigen levels of urokinase-type plasminogen activator (u-PA) and tho se of plasminogen activator inhibitor-1 (PAI-1), the endogenous inhibi tor of t-PA and u-PA, measured by enzyme-linked immunosorbent assays ( ELISAs). u-PA antigen levels from human aortic SMC incubated with PDGF 100 ng/mL and IL-4 500 U/mL were significantly greater than those inc ubated with PDGF 100 ng/mL alone. Coincubation of PDGF with IL-4 did n ot significantly increase SMC u-PA antigen levels in cellular lysates. Coincubation with PDGF 100 ng/mL and IL-4 500 U/mL did not significan tly affect SMC PAI-1 antigen levels in conditioned media or cellular l ysates. Therefore, interleukin-4 modulates vascular SMC u-PA productio n induced by PDGF.