Production of plasminogen activator inhibitor-1 (PAI-1) from BEAS-2B cells after incubation with stimulated LAD2 supernatants. (A) BEAS-2B cells were stimulated with substance P (SP) and compound 48/80 for 16 hours, and PAI-1 levels were measured by ELISA (direct stimulation). LAD2 cells were stimulated with SP, compound 48/80 (48/80), and human IgE receptor cross-linking for 24 hours, and supernatants were collected. BEAS-2B cells were incubated with the LAD2 supernatants for 16 hours (activated mast cell [MC] supernatants). Data represent means ± SE of four independent experiments performed in duplicate. *P < 0.01, **P < 0.05, and ***P < 0.005 by Student’s t test. (B) LAD2 cells were stimulated with IgE receptor cross-linking for 0.5, 8, or 24 hours, and supernatants were collected. BEAS-2B cells were incubated with the LAD2 supernatants for 16 hours. Data represent means ± SE of four independent experiments performed in duplicate. *P < 0.05 by Student’s t test.