FIGURE 2.

Metabolism of exogenous LTA₄ in FLSs. A, The expression of LTA₄H in cellular lysates from WT, 5-LO^–/–, and LTA₄H^–/– FLSs was analyzed by Western blot. The expression of heat shock protein 90 was used as a control. Results shown are representative of three separate experiments. B, LTB₄ formation by FLSs is dependent on the concentration of exogeneous LTA₄. WT FLSs (8 × 10⁴ cells per milliliter) were cultured with LTA₄ at a concentration of 0.1 or 1 μM for 20 min at 37°C. The formation of LTB₄ from exogenous LTA₄ was determined by ELISA as described in Materials and Methods. The results represent the mean ± SEM of three experiments. C, FLSs from either WTor LTA₄H^–/– mice were incubated with 1 μM LTA₄ for 20 min at 37°C. LTB₄ production in the culture supernatants was measured by ELISA. Results represent the mean ± SEM of three experiments. The p values in B and C are indicated on the top of each bar. The assay limit of detection is denoted by the horizontal dotted line.