Fibrin induction of IL-8 in HUVEC. HUVEC monolayers were incubated either with control factors such as control media (MED), fibrinogen (FGN, 1.0 mg/mL) thrombin (0.08 U/mL), or with fibrin (FN, 1.0 mg/mL) for 4 hours in the absence of serum. Since the presence of serum causes spontaneous fibrinogen clotting, serum-free culturing studies were undertaken. Previous studies in our laboratory indicated that serum-free culturing of HUVEC for more than 4 hours resulted in significant cell injury and death. Therefore, we were limited to short-term cell culture studies (ie, 4 hours) for this specific study. After incubation, the conditioned media were collected and cells were lysed with 0.1% Triton/PBS. The conditioned media (▪) and cell lysates (□) from HUVEC monolayer treated with fibrin or other control factors were tested for IL-8 induction by specific IL-8 RIA. Level of IL-8 antigen were expressed as nanogram per 1 × 106 cells. Results were expressed as the mean of IL-8 ± SD and were representative of two separate experiments with similar results. Asterisk indicates statistical significance of P ≤ .05 compared to media control.
