Platelets induce IL-8 production of SMC. SMC were incubated in 24-well plates until they reached confluency. The cultures were washed and the SMC prestimulated with (+) or without (−) recombinant TNF-α (TNF, 50 ng/mL). Untreated (−) platelets or platelets in the presence of thrombin (+; 1 U/mL) were added at a ratio of 1,000 platelets per SMC. The supernatants were harvested after 24 hours, run on a reducing SDS-PAGE, and blotted to Immobilon P. A rabbit polyclonal antibody (IL-8_54-72; 1:1,000) was added (1 hour) and the blot stained with peroxidase-conjugated goat-anti-rabbit (1 hour) and subsequent addition of DAB. Similar results were obtained in three experiments.